cpufreq: tegra186: Fix initial frequency

PATCH In review Jon Hunter 2 participants 10 messages Aug 24, 2020 – Oct 29, 2020

Subsystems (2)

Tegra architecture support CPU frequency scaling framework

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Jon Hunter

author maintainer

2020-08-24 14:59 UTC #0 lore raw

PATCH v2 1/1 cpufreq: tegra186: Fix initial frequency

Commit 6cc3d0e9a097 ("cpufreq: tegra186: add CPUFREQ_NEED_INITIAL_FREQ_CHECK flag") fixed CPUFREQ support for Tegra186 but as a consequence the following warnings are now seen on boot ...

cpufreq: cpufreq_online: CPU0: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU1: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU1: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU2: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU2: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU3: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU3: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU4: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU4: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU5: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU5: Unlisted initial frequency changed to: 2035200 KHz

Fix this by adding a 'get' callback for the Tegra186 CPUFREQ driver to retrieve the current operating frequency for a given CPU. The 'get' callback uses the current 'ndiv' value that is programmed to determine that current operating frequency.

Signed-off-by Jon Hunter <[email protected]>

---
Changes since V1:
- Moved code into a 'get' callback

 drivers/cpufreq/tegra186-cpufreq.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

drivers/cpufreq/tegra186-cpufreq.c +30 -0

index 01e1f58ba422..0d0fcff60765 100644
@@ -14,6 +14,7 @@
 
 #define EDVD_CORE_VOLT_FREQ(core)		(0x20 + (core) * 0x4)
 #define EDVD_CORE_VOLT_FREQ_F_SHIFT		0
+#define EDVD_CORE_VOLT_FREQ_F_MASK		0xffff
 #define EDVD_CORE_VOLT_FREQ_V_SHIFT		16
 
 struct tegra186_cpufreq_cluster_info {

@@ -91,10 +92,39 @@ static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy,
 	return 0;
 }
 
+static unsigned int tegra186_cpufreq_get(unsigned int cpu)
+{
+	struct cpufreq_frequency_table *tbl;
+	struct cpufreq_policy *policy;
+	void __iomem *edvd_reg;
+	unsigned int i, freq = 0;
+	u32 ndiv;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return -EINVAL;
+
+	tbl = policy->freq_table;
+	edvd_reg = policy->driver_data;
+	ndiv = readl(edvd_reg) & EDVD_CORE_VOLT_FREQ_F_MASK;
+
+	for (i = 0; tbl[i].frequency != CPUFREQ_TABLE_END; i++) {
+		if ((tbl[i].driver_data & EDVD_CORE_VOLT_FREQ_F_MASK) == ndiv) {
+			freq = tbl[i].frequency;
+			break;
+		}
+	}
+
+	cpufreq_cpu_put(policy);
+
+	return freq;
+}
+
 static struct cpufreq_driver tegra186_cpufreq_driver = {
 	.name = "tegra186",
 	.flags = CPUFREQ_STICKY | CPUFREQ_HAVE_GOVERNOR_PER_POLICY |
 			CPUFREQ_NEED_INITIAL_FREQ_CHECK,
+	.get = tegra186_cpufreq_get,
 	.verify = cpufreq_generic_frequency_table_verify,
 	.target_index = tegra186_cpufreq_set_target,
 	.init = tegra186_cpufreq_init,

Signature · 1 line

2.25.1

Viresh Kumar

maintainer

2020-08-25 05:50 UTC #1 lore raw

Quoted 48 lines · Jon Hunter

Commit 6cc3d0e9a097 ("cpufreq: tegra186: add CPUFREQ_NEED_INITIAL_FREQ_CHECK flag") fixed CPUFREQ support for Tegra186 but as a consequence the following warnings are now seen on boot ...
cpufreq: cpufreq_online: CPU0: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU1: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU1: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU2: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU2: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU3: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU3: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU4: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU4: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU5: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU5: Unlisted initial frequency changed to: 2035200 KHz
Fix this by adding a 'get' callback for the Tegra186 CPUFREQ driver to retrieve the current operating frequency for a given CPU. The 'get' callback uses the current 'ndiv' value that is programmed to determine that current operating frequency.
Signed-off-by Jon Hunter <[email protected]>
---
Changes since V1:
- Moved code into a 'get' callback
 drivers/cpufreq/tegra186-cpufreq.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
drivers/cpufreq/tegra186-cpufreq.c +2 -0
index 01e1f58ba422..0d0fcff60765 100644
@@ -14,6 +14,7 @@
 
 #define EDVD_CORE_VOLT_FREQ(core)		(0x20 + (core) * 0x4)
 #define EDVD_CORE_VOLT_FREQ_F_SHIFT		0
+#define EDVD_CORE_VOLT_FREQ_F_MASK		0xffff
 #define EDVD_CORE_VOLT_FREQ_V_SHIFT		16
 
 struct tegra186_cpufreq_cluster_info {
@@ -91,10 +92,39 @@ static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy,
 	return 0;
 }
 
+static unsigned int tegra186_cpufreq_get(unsigned int cpu)

drivers/cpufreq/tegra186-cpufreq.c static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy, · line 105

Quoted 10 lines

drivers/cpufreq/tegra186-cpufreq.c +10 -0

+{
+	struct cpufreq_frequency_table *tbl;
+	struct cpufreq_policy *policy;
+	void __iomem *edvd_reg;
+	unsigned int i, freq = 0;
+	u32 ndiv;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return -EINVAL;

This should be return 0;

Applied with that change. Thanks.

Signature · 1 line

viresh

Jon Hunter

author maintainer

2020-08-25 08:22 UTC #2 lore raw

Quoted 62 lines · Viresh Kumar

Quoted 48 lines · Jon Hunter
Commit 6cc3d0e9a097 ("cpufreq: tegra186: add CPUFREQ_NEED_INITIAL_FREQ_CHECK flag") fixed CPUFREQ support for Tegra186 but as a consequence the following warnings are now seen on boot ...
cpufreq: cpufreq_online: CPU0: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU1: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU1: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU2: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU2: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU3: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU3: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU4: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU4: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU5: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU5: Unlisted initial frequency changed to: 2035200 KHz
Fix this by adding a 'get' callback for the Tegra186 CPUFREQ driver to retrieve the current operating frequency for a given CPU. The 'get' callback uses the current 'ndiv' value that is programmed to determine that current operating frequency.
Signed-off-by Jon Hunter <[email protected]>
---
Changes since V1:
- Moved code into a 'get' callback
 drivers/cpufreq/tegra186-cpufreq.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
drivers/cpufreq/tegra186-cpufreq.c +2 -0
index 01e1f58ba422..0d0fcff60765 100644
@@ -14,6 +14,7 @@
 
 #define EDVD_CORE_VOLT_FREQ(core)		(0x20 + (core) * 0x4)
 #define EDVD_CORE_VOLT_FREQ_F_SHIFT		0
+#define EDVD_CORE_VOLT_FREQ_F_MASK		0xffff
 #define EDVD_CORE_VOLT_FREQ_V_SHIFT		16
 
 struct tegra186_cpufreq_cluster_info {
@@ -91,10 +92,39 @@ static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy,
 	return 0;
 }
 
+static unsigned int tegra186_cpufreq_get(unsigned int cpu)
drivers/cpufreq/tegra186-cpufreq.c static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy, · line 105
Quoted 10 lines
drivers/cpufreq/tegra186-cpufreq.c +10 -0
+{
+	struct cpufreq_frequency_table *tbl;
+	struct cpufreq_policy *policy;
+	void __iomem *edvd_reg;
+	unsigned int i, freq = 0;
+	u32 ndiv;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return -EINVAL;
This should be return 0;

Quoted 1 line

Applied with that change. Thanks.

OK, thanks!

Jon

Signature · 1 line

nvpublic

Jon Hunter

author maintainer

2020-10-15 14:03 UTC #3 lore raw

In reply to Viresh Kumar

Hi Viresh,

Quoted 62 lines · Viresh Kumar

Quoted 48 lines · Jon Hunter
Commit 6cc3d0e9a097 ("cpufreq: tegra186: add CPUFREQ_NEED_INITIAL_FREQ_CHECK flag") fixed CPUFREQ support for Tegra186 but as a consequence the following warnings are now seen on boot ...
cpufreq: cpufreq_online: CPU0: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU0: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU1: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU1: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU2: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU2: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU3: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU3: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU4: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU4: Unlisted initial frequency changed to: 2035200 KHz
cpufreq: cpufreq_online: CPU5: Running at unlisted freq: 0 KHz
cpufreq: cpufreq_online: CPU5: Unlisted initial frequency changed to: 2035200 KHz
Fix this by adding a 'get' callback for the Tegra186 CPUFREQ driver to retrieve the current operating frequency for a given CPU. The 'get' callback uses the current 'ndiv' value that is programmed to determine that current operating frequency.
Signed-off-by Jon Hunter <[email protected]>
---
Changes since V1:
- Moved code into a 'get' callback
 drivers/cpufreq/tegra186-cpufreq.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
drivers/cpufreq/tegra186-cpufreq.c +2 -0
index 01e1f58ba422..0d0fcff60765 100644
@@ -14,6 +14,7 @@
 
 #define EDVD_CORE_VOLT_FREQ(core)		(0x20 + (core) * 0x4)
 #define EDVD_CORE_VOLT_FREQ_F_SHIFT		0
+#define EDVD_CORE_VOLT_FREQ_F_MASK		0xffff
 #define EDVD_CORE_VOLT_FREQ_V_SHIFT		16
 
 struct tegra186_cpufreq_cluster_info {
@@ -91,10 +92,39 @@ static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy,
 	return 0;
 }
 
+static unsigned int tegra186_cpufreq_get(unsigned int cpu)
drivers/cpufreq/tegra186-cpufreq.c static int tegra186_cpufreq_set_target(struct cpufreq_policy *policy, · line 105
Quoted 10 lines
drivers/cpufreq/tegra186-cpufreq.c +10 -0
+{
+	struct cpufreq_frequency_table *tbl;
+	struct cpufreq_policy *policy;
+	void __iomem *edvd_reg;
+	unsigned int i, freq = 0;
+	u32 ndiv;
+
+	policy = cpufreq_cpu_get(cpu);
+	if (!policy)
+		return -EINVAL;
This should be return 0;

Quoted 1 line

Applied with that change. Thanks.

If not too late, would you mind dropping this patch for v5.10?

The patch was working for me locally, but when testing on more boards, I actually found this broke CPUFREQ support on some Tegra186 boards. The reason is that the boot frequency may not be in the frequency table on all boards. The boot frequency is constant across all boards, but the frequency table can vary slightly with device. Therefore, for some boards, such as mine, the boot frequency is found the in frequency table but this is not always the case.

Now that you have made the warning an info print, this change is not really needed and the simplest thing to do is dropped this completely. Sorry about that.

Jon

Signature · 1 line

nvpublic

Viresh Kumar

maintainer

2020-10-16 04:07 UTC #4 lore raw

Quoted 1 line · Jon Hunter

If not too late, would you mind dropping this patch for v5.10?

It is already part of Linus's master now.

Signature · 1 line

viresh

Jon Hunter

author maintainer

2020-10-19 09:33 UTC #5 lore raw

Quoted 4 lines · Viresh Kumar

Quoted 1 line · Jon Hunter
If not too late, would you mind dropping this patch for v5.10?
It is already part of Linus's master now.

OK, thanks. I will send a revert for this once rc1 is out.

Cheers
Jon

Signature · 1 line

nvpublic

Jon Hunter

author maintainer

2020-10-26 12:57 UTC #6 lore raw

Quoted 8 lines · Jon Hunter

Quoted 4 lines · Viresh Kumar
Quoted 1 line · Jon Hunter
If not too late, would you mind dropping this patch for v5.10?
It is already part of Linus's master now.
OK, thanks. I will send a revert for this once rc1 is out.

Thinking about this some more, what are your thoughts on making the following change?

Basically, if the driver sets the CPUFREQ_NEED_INITIAL_FREQ_CHECK, then I wonder if we should not fail if the frequency return by

Quoted 1 line

get() is not known. This would fix the problem I see on Tegra186

where the initial boot frequency may not be in the frequency table.

Cheers
Jon

drivers/cpufreq/cpufreq.c +6 -6

index f4b60663efe6..b7d3b61577b0 100644
@@ -1426,13 +1426,8 @@ static int cpufreq_online(unsigned int cpu)
                                CPUFREQ_CREATE_POLICY, policy);
        }
 
-       if (cpufreq_driver->get && has_target()) {
+       if (cpufreq_driver->get && has_target())
                policy->cur = cpufreq_driver->get(policy->cpu);
-               if (!policy->cur) {
-                       pr_err("%s: ->get() failed\n", __func__);
-                       goto out_destroy_policy;
-               }
-       }
 
        /*
         * Sometimes boot loaders set CPU frequency to a value outside of

@@ -1471,6 +1466,11 @@ static int cpufreq_online(unsigned int cpu)
                        pr_info("%s: CPU%d: Running at unlisted initial frequency: %u KHz, changing to: %u KHz\n",
                                __func__, policy->cpu, old_freq, policy->cur);
                }
+       } else {
+               if (!policy->cur) {
+                       pr_err("%s: ->get() failed\n", __func__);
+                       goto out_destroy_policy;
+               }
        }
 
        if (new_policy) {

Signature · 1 line

nvpublic

Viresh Kumar

maintainer

2020-10-28 23:15 UTC #7 lore raw

Quoted 4 lines · Jon Hunter

Thinking about this some more, what are your thoughts on making the following change?
Basically, if the driver sets the CPUFREQ_NEED_INITIAL_FREQ_CHECK,

This flag only means that the platform would like the core to check the currently programmed frequency and get it in sync with the table.

Quoted 2 lines

then I wonder if we should not fail if the frequency return by
Quoted 1 line
get() is not known.

When do we fail if the frequency isn't known ? That's the case where we try to set it to one from the table.

But (looking at your change), ->get() can't really return 0. We depend on it to get us the exact frequency the hardware is programmed at instead of reading a cached value in the software.

Quoted 2 lines

Quoted 1 line
This would fix the problem I see on Tegra186
where the initial boot frequency may not be in the frequency table.

With current mainline, what's the problem you see now ? Sorry I missed track of it a bit :)

Signature · 1 line

viresh

Jon Hunter

author maintainer

2020-10-28 22:54 UTC #8 lore raw

Quoted 8 lines · Viresh Kumar

Quoted 4 lines · Jon Hunter
Thinking about this some more, what are your thoughts on making the following change?
Basically, if the driver sets the CPUFREQ_NEED_INITIAL_FREQ_CHECK,
This flag only means that the platform would like the core to check the currently programmed frequency and get it in sync with the table.

Yes exactly.

Quoted 5 lines

Quoted 2 lines
then I wonder if we should not fail if the frequency return by
Quoted 1 line
get() is not known.
When do we fail if the frequency isn't known ? That's the case where we try to set it to one from the table.

Currently, if the frequency is not known, we fail right before we do the initial frequency check [0].

Quoted 3 lines

But (looking at your change), ->get() can't really return 0. We depend on it to get us the exact frequency the hardware is programmed at instead of reading a cached value in the software.

Actually it can and it does currently. Note in tegra186_cpufreq_get() the variable 'freq' is initialised to 0, and if no match is found, then it returns 0. This is what happens currently on some Tegra186 boards.

Quoted 5 lines

Quoted 2 lines
Quoted 1 line
This would fix the problem I see on Tegra186
where the initial boot frequency may not be in the frequency table.
With current mainline, what's the problem you see now ? Sorry I missed track of it a bit :)

No problem, this has been an on-going saga now for sometime.

Cheers
Jon

[0]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/cpufreq/cpufreq.c#n1429
[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/cpufreq/tegra186-cpufreq.c#n95

Signature · 1 line

nvpublic

Viresh Kumar

maintainer

2020-10-29 00:22 UTC #9 lore raw

Quoted 6 lines · Jon Hunter

Quoted 2 lines · Viresh Kumar
When do we fail if the frequency isn't known ? That's the case where we try to set it to one from the table.
Currently, if the frequency is not known, we fail right before we do the initial frequency check [0].

Right, so the frequency returned there is 0. By unknown I assumed that you are talking about the case where the frequency isn't found in the table.

Quoted 7 lines

Quoted 3 lines
But (looking at your change), ->get() can't really return 0. We depend on it to get us the exact frequency the hardware is programmed at instead of reading a cached value in the software.
Actually it can and it does currently. Note in tegra186_cpufreq_get() the variable 'freq' is initialised to 0, and if no match is found, then it returns 0. This is what happens currently on some Tegra186 boards.

Then there is a problem with the implementation of this helper in your case. This shouldn't try to go compare the value read from the register with the table, rather convert that directly to a meaningful frequency. Its like reading registers and then doing some computations with the values read with the parent PLLs frequency. Something like what you will normally do in the implementation of clk_get_rate().

Signature · 1 line

viresh