usb: hub: fix power good delay timing

From: Stephen Warren <[email protected]>

usb_hub_power_on() currently waits for the maximum of (a) the hub port's power output to become good, (b) the max time the USB specification allows a device to take to connect.

However, these two operations must occur in series rather than in parallel. First, the power supply ramps up to the level required to power the USB device, and then the device may take a certain amount of time to connect (assert D+/D- pullups).

Related, the maximum time that a device has to assert pullups is 1s not 100ms.

This is explained in "Connect Timing ECN.pdf", itself part of usb_20_042814.zip from www.usb.org.

Quoted 11 lines · Stephen Warren

From: Stephen Warren <[email protected]>

usb_hub_power_on() currently waits for the maximum of (a) the hub port's power output to become good, (b) the max time the USB specification allows a device to take to connect.

However, these two operations must occur in series rather than in parallel. First, the power supply ramps up to the level required to power the USB device, and then the device may take a certain amount of time to connect (assert D+/D- pullups).

Quoted 5 lines

Related, the maximum time that a device has to assert pullups is 1s not 100ms.

This is explained in "Connect Timing ECN.pdf", itself part of usb_20_042814.zip from www.usb.org.

Marek, does this series look OK?

From: Stephen Warren <[email protected]>

Now that we wait the correct specification-mandated time at the end of usb_hub_power_on(), I suspect that CONFIG_USB_HUB_MIN_POWER_ON_DELAY has no purpose.

For cm_t35.h, we already wait longer than the original MIN_POWER_ON_DELAY, so this change is safe.

For gw_ventana.h, we will wait as long as the original MIN_POWER_ON_DELAY iff pgood_delay was at least 200ms. I'm not sure if this is the case or not, hence I've CC'd relevant people to test this change.

Cc Igor Grinberg <[email protected]>

Cc Tim Harvey <[email protected]>

Signed-off-by Stephen Warren <[email protected]>

---
 README                       | 3 ---
 common/usb_hub.c             | 6 +-----
 include/configs/cm_t35.h     | 2 --
 include/configs/gw_ventana.h | 1 -
 4 files changed, 1 insertion(+), 11 deletions(-)

README +0 -3

index d8fcd95f9423..091897227c52 100644
@@ -1432,9 +1432,6 @@ The following options need to be configured:
                CONFIG_USB_EHCI_TXFIFO_THRESH enables setting of the
                txfilltuning field in the EHCI controller on reset.
 
-               CONFIG_USB_HUB_MIN_POWER_ON_DELAY defines the minimum
-               interval for usb hub power-on delay.(minimum 100msec)
-
 - USB Device:
                Define the below if you wish to use the USB console.
                Once firmware is rebuilt from a serial console issue the

common/usb_hub.c +1 -5

index 4875a51aceaf..2add4b97920f 100644
@@ -35,10 +35,6 @@
 #include <asm/4xx_pci.h>
 #endif
 
-#ifndef CONFIG_USB_HUB_MIN_POWER_ON_DELAY
-#define CONFIG_USB_HUB_MIN_POWER_ON_DELAY      1000
-#endif
-
 #define USB_BUFSIZ     512
 
 static struct usb_hub_device hub_dev[USB_MAX_HUB];

@@ -142,7 +138,7 @@ static void usb_hub_power_on(struct usb_hub_device *hub)
         * Wait for power to become stable,
         * plus spec-defined max time for device to connect
         */
-       mdelay(pgood_delay + CONFIG_USB_HUB_MIN_POWER_ON_DELAY);
+       mdelay(pgood_delay + 1000);
 }
 
 void usb_hub_reset(void)

include/configs/cm_t35.h +0 -2

index aae05e033303..f6acf6920524 100644
@@ -104,8 +104,6 @@
 #define CONFIG_USB_DEVICE
 #define CONFIG_USB_TTY
 #define CONFIG_SYS_CONSOLE_IS_IN_ENV
-/* This delay is really for slow-to-power-on USB sticks, not the hub */
-#define CONFIG_USB_HUB_MIN_POWER_ON_DELAY 500
 
 /* commands to include */
 #include <config_cmd_default.h>

include/configs/gw_ventana.h +0 -2

index 33983907f228..188871630bd3 100644
@@ -188,7 +188,6 @@
 #define CONFIG_USB_ETH_CDC
 #define CONFIG_NETCONSOLE
 #define CONFIG_SYS_USB_EVENT_POLL_VIA_CONTROL_EP
-#define CONFIG_USB_HUB_MIN_POWER_ON_DELAY 1200
 
 /* serial console (ttymxc1,115200) */
 #define CONFIG_CONS_INDEX              1
--

1.8.1.5

Quoted 14 lines · Stephen Warren

From: Stephen Warren <[email protected]>

Now that we wait the correct specification-mandated time at the end of usb_hub_power_on(), I suspect that CONFIG_USB_HUB_MIN_POWER_ON_DELAY has no purpose.

For cm_t35.h, we already wait longer than the original MIN_POWER_ON_DELAY, so this change is safe.

For gw_ventana.h, we will wait as long as the original MIN_POWER_ON_DELAY iff pgood_delay was at least 200ms. I'm not sure if this is the case or not, hence I've CC'd relevant people to test this change.

include/configs/gw_ventana.h

Quoted 2 lines

include/configs/gw_ventana.h +0 -1

 
-#define CONFIG_USB_HUB_MIN_POWER_ON_DELAY 1200

Stephen,

Sorry for the late reply - I'm just getting around to testing this (and I realize that Marek already committed it which is ok by me).

I have a variety of USB Mass Storage devices that I tested when I was looking at this and out of about 12 devices I found I had 1 'usb stick' that requires 2100ms in order to respond and be successfully

scanned: 048d:1327 Integrated Technology Express, Inc 32GB USB stick. I also found that rotational media (ie Seagate and Western Digital USB drives) would not respond in 1000ms either which didn't surprise me as I figured they needed some extra spin-up time. For all other devices I had I found that 1000ms was adequate.

So do these devices I mention simply violate the USB spec?

I wonder if the delay should be able to be overridden with an env var or an argument to 'usb start' to account for devices like this?

Yes, perhaps it is worth U-Boot probing for longer than the minimum time, either always or on-demand as requested by an environment variable. The only downside would be that "usb start" would take longer even in the absence of these broken(?) devices if we always delay longer, rather than triggering the process via an environment variable. Marek, what are your thoughts?

Quoted 23 lines · Tim Harvey

Quoted 14 lines · Stephen Warren

From: Stephen Warren <[email protected]>

Now that we wait the correct specification-mandated time at the end of usb_hub_power_on(), I suspect that CONFIG_USB_HUB_MIN_POWER_ON_DELAY has no purpose.

For cm_t35.h, we already wait longer than the original MIN_POWER_ON_DELAY, so this change is safe.

For gw_ventana.h, we will wait as long as the original MIN_POWER_ON_DELAY iff pgood_delay was at least 200ms. I'm not sure if this is the case or not, hence I've CC'd relevant people to test this change.

include/configs/gw_ventana.h

Quoted 2 lines

include/configs/gw_ventana.h +0 -1

 
-#define CONFIG_USB_HUB_MIN_POWER_ON_DELAY 1200

Stephen,

Sorry for the late reply - I'm just getting around to testing this (and I realize that Marek already committed it which is ok by me).

Quoted 3 lines

I have a variety of USB Mass Storage devices that I tested when I was looking at this and out of about 12 devices I found I had 1 'usb stick' that requires 2100ms in order to respond and be successfully

Was that 2100ms or 1200ms? I ask because gw_ventana.h only had 1200, so if devices require 2100ms then they presumably didn't work with the code before my patch?

Quoted 8 lines

scanned: 048d:1327 Integrated Technology Express, Inc 32GB USB stick. I also found that rotational media (ie Seagate and Western Digital USB drives) would not respond in 1000ms either which didn't surprise me as I figured they needed some extra spin-up time. For all other devices I had I found that 1000ms was adequate.

So do these devices I mention simply violate the USB spec?

I *think* so yes.

Quoted 2 lines

I wonder if the delay should be able to be overridden with an env var or an argument to 'usb start' to account for devices like this?

Yes, perhaps it is worth U-Boot probing for longer than the minimum time, either always or on-demand as requested by an environment variable. The only downside would be that "usb start" would take longer even in the absence of these broken(?) devices if we always delay longer, rather than triggering the process via an environment variable. Marek, what are your thoughts?