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ARM: OMAP3+: PM: VP: ensure VP is idle before disable

PATCH Superseded Nishanth Menon 4 participants 17 messages May 18, 2012 – May 31, 2012 1 message not in the archive

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Arm (32-bit) Arm sub-architectures OMAP2+ support

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A message that is not in the archive (sent off-list or not yet received): [PATCH] ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Nishanth Menon

author
#1 lore raw

PATCH v2 1/1 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

From: Wenbiao Wang <[email protected]>

Voltage Processor state machine transition to disable need to occur from IDLE state. When we transition OPP in a functioning system, the call sequence for an OPP transition is as follows:
omap_sr_disable

      -> sr class 3 disable
           -> vp disable
           -> sr disable

forceupdate to voltage/frequency scale depending on which OPP we are transitioning to.

If we hit a critical timing window where SR had commanded VP for a voltage transition and VP is in the middle of operating on that command, it needs to go through a few states before going to update state(where it actually sends the command to VC). Initial view of h/w owners is that the state disable of VP is expected to be sampled for the next transition.

Instead, to be on a safer side, we ensure that the valid states of the VP state machine is diligently followed by software. This can be done by waiting for VP to be in idle prior to disabling VP. Existing prints have been updated to ensure context is available on error messages.

As part of this change, increase timeout for VP idle check to improbable 500uSec to be certain that system is indeed unable to continue before crashing out with error(worst case expectancy remains the same 3-100uSec depending on when we caught VP).

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
[nm at ti.com: port from android]
Signed-off-by Nishanth Menon <[email protected]>
Signed-off-by Wenbiao Wang <[email protected]>

---
V2: fix commit message - picked up redundant info from get_maintainer.pl Apologies on the spam

V1: http://marc.info/?l=linux-omap&m=133736493721977&w=2

 arch/arm/mach-omap2/vp.c |   15 +++++++++++++--
 arch/arm/mach-omap2/vp.h |    2 +-
 2 files changed, 14 insertions(+), 3 deletions(-)
arch/arm/mach-omap2/vp.c +13 -2
index f95c1ba..925d869 100644
@@ -262,6 +262,17 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 		return;
 	}
 
+	/*
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * Depending on if we catch VP in the middle of an SR operation.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout before disable\n",
+			   __func__, voltdm->name);
+
 	/* Disable VP */
 	vpconfig = voltdm->read(vp->vpconfig);
 	vpconfig &= ~vp->common->vpconfig_vpenable;

@@ -274,8 +285,8 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 			  VP_IDLE_TIMEOUT, timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
-		pr_warning("%s: vdd_%s idle timedout\n",
-			__func__, voltdm->name);
+		pr_warning("%s: vdd_%s idle timedout after disable\n",
+			   __func__, voltdm->name);
 
 	vp->enabled = false;
arch/arm/mach-omap2/vp.h +1 -1
index 7c155d2..0abf895 100644
@@ -31,7 +31,7 @@ struct voltagedomain;
 #define OMAP4_VP_VDD_MPU_ID 2
 
 /* XXX document */
-#define VP_IDLE_TIMEOUT		200
+#define VP_IDLE_TIMEOUT		500
 #define VP_TRANXDONE_TIMEOUT	300
 
 /**
Signature · 1 line
1.7.9.5
#2 lore raw

PATCH v2 1/1 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Hello,

Minor suggestion.

Quoted 30 lines · ext Nishanth Menon

From: Wenbiao Wang <[email protected]>

Voltage Processor state machine transition to disable need to occur from IDLE state. When we transition OPP in a functioning system, the call sequence for an OPP transition is as follows:
omap_sr_disable

      -> sr class 3 disable
           -> vp disable
           -> sr disable

forceupdate to voltage/frequency scale depending on which OPP we are transitioning to.

If we hit a critical timing window where SR had commanded VP for a voltage transition and VP is in the middle of operating on that command, it needs to go through a few states before going to update state(where it actually sends the command to VC). Initial view of h/w owners is that the state disable of VP is expected to be sampled for the next transition.

Instead, to be on a safer side, we ensure that the valid states of the VP state machine is diligently followed by software. This can be done by waiting for VP to be in idle prior to disabling VP. Existing prints have been updated to ensure context is available on error messages.

As part of this change, increase timeout for VP idle check to improbable 500uSec to be certain that system is indeed unable to continue before crashing out with error(worst case expectancy remains the same 3-100uSec depending on when we caught VP).

<cut>

arch/arm/mach-omap2/vp.h struct voltagedomain; · line 34

Quoted 4 lines

/* XXX document */

arch/arm/mach-omap2/vp.h +1 -1
-#define VP_IDLE_TIMEOUT		200
+#define VP_IDLE_TIMEOUT		500

I guess it is time to properly document this increasing busy loop delay.. As it is getting closer to ms scale..

Quoted 11 lines

#define VP_TRANXDONE_TIMEOUT 300

/**

Signature · 7 lines
1.7.9.5


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linux-arm-kernel mailing list
linux-arm-kernel at lists.infradead.org
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author
#3 lore raw

PATCH v2 1/1 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Sat, May 19, 2012 at 4:52 AM, Eduardo Valentin <[email protected]>

Quoted 4 lines · wrote:

I guess it is time to properly document this increasing busy loop delay.. As it is getting closer to ms scale..

Does the following sound good?
/* Maximum time for Voltage Processor to enter or exit idle */

Regards,
Nishanth Menon

#4 lore raw

PATCH v2 1/1 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Hello,

Quoted 8 lines · ext Nishanth Menon

Sat, May 19, 2012 at 4:52 AM, Eduardo Valentin <[email protected]>

Quoted 4 lines · wrote:

I guess it is time to properly document this increasing busy loop delay.. As it is getting closer to ms scale..

Does the following sound good?
/* Maximum time for Voltage Processor to enter or exit idle */

Sounds way better :-). If you have an estimation of how long it takes in the average case, it might help. But I am OK already with the above, in case you don't have the estimation.

Quoted 3 lines

Regards,
Nishanth Menon

Cheers,

--
Eduardo Valentin

author
#5 lore raw

PATCH v2 1/1 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Quoted 7 lines · Eduardo Valentin
Quoted 4 lines · ext Nishanth Menon

?Sat, May 19, 2012 at 4:52 AM, Eduardo Valentin <[email protected]>

Quoted 2 lines · wrote:
Quoted 8 lines
Quoted 4 lines
Quoted 2 lines

I guess it is time to properly document this increasing busy loop delay.. As it is getting closer to ms scale..

Does the following sound good?
/* Maximum time for Voltage Processor to enter or exit idle */

Sounds way better :-). If you have an estimation of how long it takes in the average case, it might help. But I am OK already with the above, in case you don't have the estimation.

/*
* Maximum time for Voltage Processor to enter or exit idle
* worst case is around 100uSec depending on when we intercepted VP
* we use 5 times worst case value to be sure that the system flags
* invalid condition
*/
better?

Regards,
Nishanth Menon

#6 lore raw

PATCH v2 1/1 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Hello,

Quoted 17 lines · Nishanth
Quoted 7 lines · Eduardo Valentin
Quoted 4 lines · ext Nishanth Menon

?Sat, May 19, 2012 at 4:52 AM, Eduardo Valentin <[email protected]>

Quoted 2 lines · wrote:
Quoted 8 lines
Quoted 4 lines
Quoted 2 lines

I guess it is time to properly document this increasing busy loop delay.. As it is getting closer to ms scale..

Does the following sound good?
/* Maximum time for Voltage Processor to enter or exit idle */

Sounds way better :-). If you have an estimation of how long it takes in the average case, it might help. But I am OK already with the above, in case you don't have the estimation.

Quoted 7 lines

/*
?* Maximum time for Voltage Processor to enter or exit idle ?* worst case is around 100uSec depending on when we intercepted VP ?* we use 5 times worst case value to be sure that the system flags ?* invalid condition
?*/
better?

Yes! Thanks.

Quoted 3 lines

Regards,
Nishanth Menon

Signature · 1 line
Eduardo Valentin
author
#7 lore raw

cover ARM: OMAP3+: VP: collate fixes

In reply to a message not in the archive

Reviewing the android code base brought out a few fixes that upstream does not have, so collating them and posting them out in this chain.

Nishanth Menon (2):
ARM: OMAP3+: PM: VP: check to ensure VP is idle before forceupdate
ARM: OMAP3+: PM: VP: check only the VPINIDLE status bit

Wenbiao Wang (1):
ARM: OMAP3+: PM: VP: ensure VP is idle before disable

 arch/arm/mach-omap2/vp.c          |   34 ++++++++++++++++++++++++++++++----
 arch/arm/mach-omap2/vp.h          |    3 ++-
 arch/arm/mach-omap2/vp3xxx_data.c |    1 +
 arch/arm/mach-omap2/vp44xx_data.c |    1 +
 4 files changed, 34 insertions(+), 5 deletions(-)

Cc: Tony Lindgren <[email protected]>
Cc: Kevin Hilman <[email protected]>
Cc: linux-omap at vger.kernel.org
Cc: linux-arm-kernel at lists.infradead.org
Regards,
Nishanth Menon

Signature · 1 line
1.7.9.5
author
#8 lore raw

PATCH 1/3 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

From: Wenbiao Wang <[email protected]>

Voltage Processor state machine transition to disable need to occur from IDLE state. When we transition OPP in a functioning system, the call sequence for an OPP transition is as follows:
omap_sr_disable

      -> sr class 3 disable
           -> vp disable
           -> sr disable

forceupdate to voltage/frequency scale depending on which OPP we are transitioning to.

If we hit a critical timing window where SR had commanded VP for a voltage transition and VP is in the middle of operating on that command, it needs to go through a few states before going to update state(where it actually sends the command to VC). Initial view of h/w owners is that the state disable of VP is expected to be sampled for the next transition.

Instead, to be on a safer side, we ensure that the valid states of the VP state machine is diligently followed by software. This can be done by waiting for VP to be in idle prior to disabling VP. Existing prints have been updated to ensure context is available on error messages.

As part of this change, increase timeout for VP idle check to improbable 500uSec to be certain that system is indeed unable to continue before crashing out with error(worst case expectancy remains the same 3-100uSec depending on when we caught VP).

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
[nm at ti.com: port from android]
Signed-off-by Nishanth Menon <[email protected]>
Signed-off-by Wenbiao Wang <[email protected]>
---
 arch/arm/mach-omap2/vp.c |   15 +++++++++++++--
 arch/arm/mach-omap2/vp.h |    2 +-
 2 files changed, 14 insertions(+), 3 deletions(-)
arch/arm/mach-omap2/vp.c +13 -2
index f95c1ba..925d869 100644
@@ -262,6 +262,17 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 		return;
 	}
 
+	/*
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * Depending on if we catch VP in the middle of an SR operation.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout before disable\n",
+			   __func__, voltdm->name);
+
 	/* Disable VP */
 	vpconfig = voltdm->read(vp->vpconfig);
 	vpconfig &= ~vp->common->vpconfig_vpenable;

@@ -274,8 +285,8 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 			  VP_IDLE_TIMEOUT, timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
-		pr_warning("%s: vdd_%s idle timedout\n",
-			__func__, voltdm->name);
+		pr_warning("%s: vdd_%s idle timedout after disable\n",
+			   __func__, voltdm->name);
 
 	vp->enabled = false;
arch/arm/mach-omap2/vp.h +1 -1
index 7c155d2..0abf895 100644
@@ -31,7 +31,7 @@ struct voltagedomain;
 #define OMAP4_VP_VDD_MPU_ID 2
 
 /* XXX document */
-#define VP_IDLE_TIMEOUT		200
+#define VP_IDLE_TIMEOUT		500
 #define VP_TRANXDONE_TIMEOUT	300
 
 /**
Signature · 1 line
1.7.9.5
#9 lore raw

PATCH 1/3 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Quoted 52 lines · Nishanth Menon

From: Wenbiao Wang <[email protected]>

Voltage Processor state machine transition to disable need to occur from IDLE state. When we transition OPP in a functioning system, the call sequence for an OPP transition is as follows:
omap_sr_disable

      -> sr class 3 disable
           -> vp disable
           -> sr disable

forceupdate to voltage/frequency scale depending on which OPP we are transitioning to.

If we hit a critical timing window where SR had commanded VP for a voltage transition and VP is in the middle of operating on that command, it needs to go through a few states before going to update state(where it actually sends the command to VC). Initial view of h/w owners is that the state disable of VP is expected to be sampled for the next transition.

Instead, to be on a safer side, we ensure that the valid states of the VP state machine is diligently followed by software. This can be done by waiting for VP to be in idle prior to disabling VP. Existing prints have been updated to ensure context is available on error messages.

As part of this change, increase timeout for VP idle check to improbable 500uSec to be certain that system is indeed unable to continue before crashing out with error(worst case expectancy remains the same 3-100uSec depending on when we caught VP).

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
[nm at ti.com: port from android]
Signed-off-by Nishanth Menon <[email protected]>
Signed-off-by Wenbiao Wang <[email protected]>
---
 arch/arm/mach-omap2/vp.c |   15 +++++++++++++--
 arch/arm/mach-omap2/vp.h |    2 +-
 2 files changed, 14 insertions(+), 3 deletions(-)
arch/arm/mach-omap2/vp.c +1 -0
index f95c1ba..925d869 100644
@@ -262,6 +262,17 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 		return;
 	}
 
+	/*

arch/arm/mach-omap2/vp.c void omap_vp_disable(struct voltagedomain *voltdm) · line 275

Quoted 10 lines
arch/arm/mach-omap2/vp.c +10 -0
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * Depending on if we catch VP in the middle of an SR operation.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout before disable\n",
+			   __func__, voltdm->name);
+

Shouldn't this bail out here instead of continuing to disable VP?

It would be even better to have some error recovery (or at least clean failure) here rather than just printing a warning and continuing.

Quoted 19 lines
arch/arm/mach-omap2/vp.c +2 -2
 	/* Disable VP */
 	vpconfig = voltdm->read(vp->vpconfig);
 	vpconfig &= ~vp->common->vpconfig_vpenable;

@@ -274,8 +285,8 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 			  VP_IDLE_TIMEOUT, timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
-		pr_warning("%s: vdd_%s idle timedout\n",
-			__func__, voltdm->name);
+		pr_warning("%s: vdd_%s idle timedout after disable\n",
+			   __func__, voltdm->name);
 
 	vp->enabled = false;
arch/arm/mach-omap2/vp.h +0 -0
index 7c155d2..0abf895 100644

arch/arm/mach-omap2/vp.h struct voltagedomain; · line 34

Quoted 5 lines
arch/arm/mach-omap2/vp.h +1 -1
@@ -31,7 +31,7 @@ struct voltagedomain;
 #define OMAP4_VP_VDD_MPU_ID 2
 
 /* XXX document */
-#define VP_IDLE_TIMEOUT		200
+#define VP_IDLE_TIMEOUT		500

Were you planning to insert the comment here as suggested by Eduardo?

Kevin

Quoted 3 lines
arch/arm/mach-omap2/vp.h +0 -0
 #define VP_TRANXDONE_TIMEOUT	300
 
 /**
#10 lore raw

PATCH 1/3 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

Quoted 11 lines · Kevin Hilman
Quoted 10 lines
arch/arm/mach-omap2/vp.h +0 -0
Quoted 9 lines

index 7c155d2..0abf895 100644
--- a/arch/arm/mach-omap2/vp.h
+++ b/arch/arm/mach-omap2/vp.h

 @@ -31,7 +31,7 @@ struct voltagedomain;
   #define OMAP4_VP_VDD_MPU_ID 2

   /* XXX document */

-#define VP_IDLE_TIMEOUT 200
+#define VP_IDLE_TIMEOUT 500

Were you planning to insert the comment here as suggested by Eduardo?

Oops, ignore this comment. I see you posted a v3 with this added.

Sorry,

Kevin

author
#11 lore raw

PATCH 1/3 ARM: OMAP3+: PM: VP: ensure VP is idle before disable

In reply to Kevin Hilman
Quoted 53 lines · Kevin Hilman
Quoted 51 lines · Nishanth Menon

From: Wenbiao Wang <[email protected]>

Voltage Processor state machine transition to disable need to occur from IDLE state. When we transition OPP in a functioning system, the call sequence for an OPP transition is as follows:
omap_sr_disable

      -> sr class 3 disable
           -> vp disable
           -> sr disable

forceupdate to voltage/frequency scale depending on which OPP we are transitioning to.

If we hit a critical timing window where SR had commanded VP for a voltage transition and VP is in the middle of operating on that command, it needs to go through a few states before going to update state(where it actually sends the command to VC). Initial view of h/w owners is that the state disable of VP is expected to be sampled for the next transition.

Instead, to be on a safer side, we ensure that the valid states of the VP state machine is diligently followed by software. This can be done by waiting for VP to be in idle prior to disabling VP. Existing prints have been updated to ensure context is available on error messages.

As part of this change, increase timeout for VP idle check to improbable 500uSec to be certain that system is indeed unable to continue before crashing out with error(worst case expectancy remains the same 3-100uSec depending on when we caught VP).

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
[nm at ti.com: port from android]
Signed-off-by Nishanth Menon <[email protected]>
Signed-off-by Wenbiao Wang <[email protected]>
---
 arch/arm/mach-omap2/vp.c |   15 +++++++++++++--
 arch/arm/mach-omap2/vp.h |    2 +-
 2 files changed, 14 insertions(+), 3 deletions(-)
arch/arm/mach-omap2/vp.c +0 -0
index f95c1ba..925d869 100644
@@ -262,6 +262,17 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 		return;
 	}
Quoted 13 lines

arch/arm/mach-omap2/vp.c void omap_vp_disable(struct voltagedomain *voltdm) · line 275

Quoted 11 lines
arch/arm/mach-omap2/vp.c +11 -0
+	/*
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * Depending on if we catch VP in the middle of an SR operation.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout before disable\n",
+			   __func__, voltdm->name);
+

Shouldn't this bail out here instead of continuing to disable VP?

yes - but then the entire voltage path is without error handling :( I think the cleanup should be done independent of this patch - just doing a return at this point might actually not effective.

Quoted 3 lines

It would be even better to have some error recovery (or at least clean failure) here rather than just printing a warning and continuing.

Once VP does not idle, it is an indication that something seriously has gone wrong in the VP state machine. VP in PRM module is reset only on cold reset - so even a traditional arch_reset would not help us here.

The intent here is to be completely sure that VP is in idle state before we trigger a disable. With the cleanup of all error handling flows, we might be able to flag all the way back up to calling event (a DVFS event) and may even be able to trigger appropriate recovery mechanism.

Quoted 22 lines
Quoted 22 lines
arch/arm/mach-omap2/vp.c +2 -2
 	/* Disable VP */
 	vpconfig = voltdm->read(vp->vpconfig);
 	vpconfig &= ~vp->common->vpconfig_vpenable;

@@ -274,8 +285,8 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 			  VP_IDLE_TIMEOUT, timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
-		pr_warning("%s: vdd_%s idle timedout\n",
-			__func__, voltdm->name);
+		pr_warning("%s: vdd_%s idle timedout after disable\n",
+			   __func__, voltdm->name);
 
 	vp->enabled = false;
arch/arm/mach-omap2/vp.h +0 -0
index 7c155d2..0abf895 100644
@@ -31,7 +31,7 @@ struct voltagedomain;
 #define OMAP4_VP_VDD_MPU_ID 2
Quoted 5 lines

arch/arm/mach-omap2/vp.h struct voltagedomain; · line 34

Quoted 3 lines
arch/arm/mach-omap2/vp.h +1 -1
 /* XXX document */
-#define VP_IDLE_TIMEOUT		200
+#define VP_IDLE_TIMEOUT		500

Were you planning to insert the comment here as suggested by Eduardo?

yep. waiting in case we have more comments :)
---
Regards,
Nishanth Menon

author
#12 lore raw

PATCH 2/3 ARM: OMAP3+: PM: VP: check to ensure VP is idle before forceupdate

In reply to Nishanth Menon

Ideally in the flow of DVFS programming, VP should be in idle state (since we disabled it) before entering forceupdate. Ensure that this is the case. Not doing this could cause VP statemachine to enter invalid states.

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
Signed-off-by Vinay Amancha <[email protected]>
Signed-off-by Nishanth Menon <[email protected]>
---
 arch/arm/mach-omap2/vp.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)
arch/arm/mach-omap2/vp.c +12 -0
index 925d869..985091b 100644
@@ -123,6 +123,18 @@ int omap_vp_forceupdate_scale(struct voltagedomain *voltdm,
 	u8 target_vsel, current_vsel;
 	int ret, timeout = 0;
 
+/*
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * This is an additional allowance to ensure we are in proper state
+	 * to enter into forceupdate state transition.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout forceupdate(v=%ld)\n",
+			   __func__, voltdm->name, target_volt);
+
 	ret = omap_vc_pre_scale(voltdm, target_volt, &target_vsel, &current_vsel);
 	if (ret)
 		return ret;
Signature · 1 line
1.7.9.5
#13 lore raw

PATCH 2/3 ARM: OMAP3+: PM: VP: check to ensure VP is idle before forceupdate

Quoted 21 lines · Nishanth Menon

Ideally in the flow of DVFS programming, VP should be in idle state (since we disabled it) before entering forceupdate. Ensure that this is the case. Not doing this could cause VP statemachine to enter invalid states.

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
Signed-off-by Vinay Amancha <[email protected]>
Signed-off-by Nishanth Menon <[email protected]>
---
 arch/arm/mach-omap2/vp.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)
arch/arm/mach-omap2/vp.c +0 -0
index 925d869..985091b 100644

arch/arm/mach-omap2/vp.c int omap_vp_forceupdate_scale(struct voltagedomain *voltdm, · line 126

Quoted 4 lines
arch/arm/mach-omap2/vp.c +1 -0
@@ -123,6 +123,18 @@ int omap_vp_forceupdate_scale(struct voltagedomain *voltdm,
 	u8 target_vsel, current_vsel;
 	int ret, timeout = 0;
 
+/*

missing indent

arch/arm/mach-omap2/vp.c int omap_vp_forceupdate_scale(struct voltagedomain *voltdm, · line 137

Quoted 11 lines
arch/arm/mach-omap2/vp.c +11 -0
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * This is an additional allowance to ensure we are in proper state
+	 * to enter into forceupdate state transition.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout forceupdate(v=%ld)\n",
+			   __func__, voltdm->name, target_volt);
+

Again, some clean failure and error recovery should be done here instead of just a print and bail.

Kevin

Quoted 3 lines
arch/arm/mach-omap2/vp.c +0 -0
 	ret = omap_vc_pre_scale(voltdm, target_volt, &target_vsel, &current_vsel);
 	if (ret)
 		return ret;
author
#14 lore raw

PATCH 2/3 ARM: OMAP3+: PM: VP: check to ensure VP is idle before forceupdate

Quoted 26 lines · Kevin Hilman
Quoted 24 lines · Nishanth Menon

Ideally in the flow of DVFS programming, VP should be in idle state (since we disabled it) before entering forceupdate. Ensure that this is the case. Not doing this could cause VP statemachine to enter invalid states.

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
Signed-off-by Vinay Amancha <[email protected]>
Signed-off-by Nishanth Menon <[email protected]>
---
 arch/arm/mach-omap2/vp.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)
arch/arm/mach-omap2/vp.c +0 -0
index 925d869..985091b 100644
@@ -123,6 +123,18 @@ int omap_vp_forceupdate_scale(struct voltagedomain *voltdm,
 	u8 target_vsel, current_vsel;
 	int ret, timeout = 0;
Quoted 3 lines

arch/arm/mach-omap2/vp.c int omap_vp_forceupdate_scale(struct voltagedomain *voltdm, · line 126

Quoted 1 line
arch/arm/mach-omap2/vp.c +1 -0
+/*

missing indent

oops. will fix

Quoted 15 lines

arch/arm/mach-omap2/vp.c int omap_vp_forceupdate_scale(struct voltagedomain *voltdm, · line 137

Quoted 12 lines
arch/arm/mach-omap2/vp.c +11 -0
+	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
+	 * This is an additional allowance to ensure we are in proper state
+	 * to enter into forceupdate state transition.
+	 */
+	omap_test_timeout((voltdm->read(vp->vstatus)),
+			  VP_IDLE_TIMEOUT, timeout);
+
+	if (timeout >= VP_IDLE_TIMEOUT)
+		pr_warning("%s: vdd_%s idle timedout forceupdate(v=%ld)\n",
+			   __func__, voltdm->name, target_volt);
+

Again, some clean failure and error recovery should be done here instead of just a print and bail.

thx - we should at least refuse to do forceupdate at this point.

Signature · 2 lines
Regards,
Nishanth Menon
author
#15 lore raw

PATCH 3/3 ARM: OMAP3+: PM: VP: check only the VPINIDLE status bit

In reply to Nishanth Menon

Currently we check against the entire 32 bits of the status register Where, bits 1-31 are marked as reserved and mentioned in TRM as read returns undefined values. Hence, check against purely the vpinidle status bit.

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
Reported-by Vinay Amancha <[email protected]>
Signed-off-by Nishanth Menon <[email protected]>
---
 arch/arm/mach-omap2/vp.c          |   15 +++++++++------
 arch/arm/mach-omap2/vp.h          |    1 +
 arch/arm/mach-omap2/vp3xxx_data.c |    1 +
 arch/arm/mach-omap2/vp44xx_data.c |    1 +
 4 files changed, 12 insertions(+), 6 deletions(-)
arch/arm/mach-omap2/vp.c +9 -6
index 985091b..cdcac16 100644
@@ -128,8 +128,9 @@ int omap_vp_forceupdate_scale(struct voltagedomain *voltdm,
 	 * This is an additional allowance to ensure we are in proper state
 	 * to enter into forceupdate state transition.
 	 */
-	omap_test_timeout((voltdm->read(vp->vstatus)),
-			  VP_IDLE_TIMEOUT, timeout);
+	omap_test_timeout((voltdm->read(vp->vstatus) &
+			   vp->common->vstatus_vpidle), VP_IDLE_TIMEOUT,
+			  timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
 		pr_warning("%s: vdd_%s idle timedout forceupdate(v=%ld)\n",

@@ -278,8 +279,9 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
 	 * Depending on if we catch VP in the middle of an SR operation.
 	 */
-	omap_test_timeout((voltdm->read(vp->vstatus)),
-			  VP_IDLE_TIMEOUT, timeout);
+	omap_test_timeout((voltdm->read(vp->vstatus) &
+			   vp->common->vstatus_vpidle), VP_IDLE_TIMEOUT,
+			  timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
 		pr_warning("%s: vdd_%s idle timedout before disable\n",

@@ -293,8 +295,9 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 	/*
 	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
 	 */
-	omap_test_timeout((voltdm->read(vp->vstatus)),
-			  VP_IDLE_TIMEOUT, timeout);
+	omap_test_timeout((voltdm->read(vp->vstatus) &
+			   vp->common->vstatus_vpidle), VP_IDLE_TIMEOUT,
+			  timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
 		pr_warning("%s: vdd_%s idle timedout after disable\n",
arch/arm/mach-omap2/vp.h +1 -0
index 0abf895..876b5ab 100644
@@ -73,6 +73,7 @@ struct omap_vp_common {
 	u8 vpconfig_initvdd;
 	u8 vpconfig_forceupdate;
 	u8 vpconfig_vpenable;
+	u8 vstatus_vpidle;
 	u8 vstepmin_stepmin_shift;
 	u8 vstepmin_smpswaittimemin_shift;
 	u8 vstepmax_stepmax_shift;
arch/arm/mach-omap2/vp3xxx_data.c +1 -0
index bd89f80..a65909b 100644
@@ -44,6 +44,7 @@ static const struct omap_vp_common omap3_vp_common = {
 	.vpconfig_initvdd = OMAP3430_INITVDD_MASK,
 	.vpconfig_forceupdate = OMAP3430_FORCEUPDATE_MASK,
 	.vpconfig_vpenable = OMAP3430_VPENABLE_MASK,
+	.vstatus_vpidle = OMAP3430_VPINIDLE_MASK,
 	.vstepmin_smpswaittimemin_shift = OMAP3430_SMPSWAITTIMEMIN_SHIFT,
 	.vstepmax_smpswaittimemax_shift = OMAP3430_SMPSWAITTIMEMAX_SHIFT,
 	.vstepmin_stepmin_shift = OMAP3430_VSTEPMIN_SHIFT,
arch/arm/mach-omap2/vp44xx_data.c +1 -0
index 8c031d1..9d14881 100644
@@ -44,6 +44,7 @@ static const struct omap_vp_common omap4_vp_common = {
 	.vpconfig_initvdd = OMAP4430_INITVDD_MASK,
 	.vpconfig_forceupdate = OMAP4430_FORCEUPDATE_MASK,
 	.vpconfig_vpenable = OMAP4430_VPENABLE_MASK,
+	.vstatus_vpidle = OMAP4430_VPINIDLE_MASK,
 	.vstepmin_smpswaittimemin_shift = OMAP4430_SMPSWAITTIMEMIN_SHIFT,
 	.vstepmax_smpswaittimemax_shift = OMAP4430_SMPSWAITTIMEMAX_SHIFT,
 	.vstepmin_stepmin_shift = OMAP4430_VSTEPMIN_SHIFT,
Signature · 1 line
1.7.9.5
#16 lore raw

PATCH 3/3 ARM: OMAP3+: PM: VP: check only the VPINIDLE status bit

Quoted 3 lines · Nishanth Menon

Currently we check against the entire 32 bits of the status register Where, bits 1-31 are marked as reserved and mentioned in TRM as read returns undefined values.

ouch

Quoted 9 lines

Hence, check against purely the vpinidle status bit.

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
Reported-by Vinay Amancha <[email protected]>
Signed-off-by Nishanth Menon <[email protected]>

Thanks for the fix.

Looking at this combined with the previous patches, since this same thing is done several places, it looks like we need a helper function 'omap_vp_wait_for_idle()' or similar. That function will do the check, wait for timeout, and return an error if failure. The callers can than do appropriate error handling upon failure.

Thanks,

Kevin

Quoted 83 lines
---
 arch/arm/mach-omap2/vp.c          |   15 +++++++++------
 arch/arm/mach-omap2/vp.h          |    1 +
 arch/arm/mach-omap2/vp3xxx_data.c |    1 +
 arch/arm/mach-omap2/vp44xx_data.c |    1 +
 4 files changed, 12 insertions(+), 6 deletions(-)
arch/arm/mach-omap2/vp.c +9 -6
index 985091b..cdcac16 100644
@@ -128,8 +128,9 @@ int omap_vp_forceupdate_scale(struct voltagedomain *voltdm,
 	 * This is an additional allowance to ensure we are in proper state
 	 * to enter into forceupdate state transition.
 	 */
-	omap_test_timeout((voltdm->read(vp->vstatus)),
-			  VP_IDLE_TIMEOUT, timeout);
+	omap_test_timeout((voltdm->read(vp->vstatus) &
+			   vp->common->vstatus_vpidle), VP_IDLE_TIMEOUT,
+			  timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
 		pr_warning("%s: vdd_%s idle timedout forceupdate(v=%ld)\n",

@@ -278,8 +279,9 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
 	 * Depending on if we catch VP in the middle of an SR operation.
 	 */
-	omap_test_timeout((voltdm->read(vp->vstatus)),
-			  VP_IDLE_TIMEOUT, timeout);
+	omap_test_timeout((voltdm->read(vp->vstatus) &
+			   vp->common->vstatus_vpidle), VP_IDLE_TIMEOUT,
+			  timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
 		pr_warning("%s: vdd_%s idle timedout before disable\n",

@@ -293,8 +295,9 @@ void omap_vp_disable(struct voltagedomain *voltdm)
 	/*
 	 * Wait for VP idle Typical latency is <2us. Maximum latency is ~100us
 	 */
-	omap_test_timeout((voltdm->read(vp->vstatus)),
-			  VP_IDLE_TIMEOUT, timeout);
+	omap_test_timeout((voltdm->read(vp->vstatus) &
+			   vp->common->vstatus_vpidle), VP_IDLE_TIMEOUT,
+			  timeout);
 
 	if (timeout >= VP_IDLE_TIMEOUT)
 		pr_warning("%s: vdd_%s idle timedout after disable\n",
arch/arm/mach-omap2/vp.h +1 -0
index 0abf895..876b5ab 100644
@@ -73,6 +73,7 @@ struct omap_vp_common {
 	u8 vpconfig_initvdd;
 	u8 vpconfig_forceupdate;
 	u8 vpconfig_vpenable;
+	u8 vstatus_vpidle;
 	u8 vstepmin_stepmin_shift;
 	u8 vstepmin_smpswaittimemin_shift;
 	u8 vstepmax_stepmax_shift;
arch/arm/mach-omap2/vp3xxx_data.c +1 -0
index bd89f80..a65909b 100644
@@ -44,6 +44,7 @@ static const struct omap_vp_common omap3_vp_common = {
 	.vpconfig_initvdd = OMAP3430_INITVDD_MASK,
 	.vpconfig_forceupdate = OMAP3430_FORCEUPDATE_MASK,
 	.vpconfig_vpenable = OMAP3430_VPENABLE_MASK,
+	.vstatus_vpidle = OMAP3430_VPINIDLE_MASK,
 	.vstepmin_smpswaittimemin_shift = OMAP3430_SMPSWAITTIMEMIN_SHIFT,
 	.vstepmax_smpswaittimemax_shift = OMAP3430_SMPSWAITTIMEMAX_SHIFT,
 	.vstepmin_stepmin_shift = OMAP3430_VSTEPMIN_SHIFT,
arch/arm/mach-omap2/vp44xx_data.c +1 -0
index 8c031d1..9d14881 100644
@@ -44,6 +44,7 @@ static const struct omap_vp_common omap4_vp_common = {
 	.vpconfig_initvdd = OMAP4430_INITVDD_MASK,
 	.vpconfig_forceupdate = OMAP4430_FORCEUPDATE_MASK,
 	.vpconfig_vpenable = OMAP4430_VPENABLE_MASK,
+	.vstatus_vpidle = OMAP4430_VPINIDLE_MASK,
 	.vstepmin_smpswaittimemin_shift = OMAP4430_SMPSWAITTIMEMIN_SHIFT,
 	.vstepmax_smpswaittimemax_shift = OMAP4430_SMPSWAITTIMEMAX_SHIFT,
 	.vstepmin_stepmin_shift = OMAP4430_VSTEPMIN_SHIFT,
author
#17 lore raw

PATCH 3/3 ARM: OMAP3+: PM: VP: check only the VPINIDLE status bit

Quoted 18 lines · Kevin Hilman
Quoted 3 lines · Nishanth Menon

Currently we check against the entire 32 bits of the status register Where, bits 1-31 are marked as reserved and mentioned in TRM as read returns undefined values.

ouch

Quoted 9 lines

Hence, check against purely the vpinidle status bit.

Cc Tony Lindgren <[email protected]>
Cc Kevin Hilman <[email protected]>
Cc linux-omap at vger.kernel.org
Cc linux-arm-kernel at lists.infradead.org
Reported-by Vinay Amancha <[email protected]>
Signed-off-by Nishanth Menon <[email protected]>
Quoted 8 lines

Thanks for the fix.

Looking at this combined with the previous patches, since this same thing is done several places, it looks like we need a helper function 'omap_vp_wait_for_idle()' or similar. That function will do the check, wait for timeout, and return an error if failure. The callers can than do appropriate error handling upon failure.

yep - i think a static inline should do just fine here considering just a test_timeout is involved.
will post out a new series in a few mins.

Signature · 2 lines
Regards,
Nishanth Menon