[PATCH master] usb: dwc2: increase timeout for waiting on host mode

[Sascha Hauer]

On Wed, Apr 21, 2021 at 10:50:52AM +0200, Ahmad Fatoum wrote:
> Hello Jules,
> 
> On 21.04.21 10:47, Jules Maselbas wrote:
> > Hi Ahmad,
> > 
> > On Wed, Apr 21, 2021 at 09:27:04AM +0200, Ahmad Fatoum wrote:
> >> Commit 26459ab7803a ("usb: dwc2: Rework wait for host mode during
> >> core reset") effectively reduced the timeout on switch to host mode
> >> from 200ms to 110 us, which is insufficient for the IP on the Raspberry
> >> Pi 3b, leading to:
> >>
> >>   dwc2 3f980000.usb at 7e980000.of: dwc2_wait_for_mode: Couldn't set host mode
> >>
> >> and an unusable USB (and Ethernet) after.
> >>
> >> Bump up the timeout to 200ms and help future debugging by logging how
> >> much time it actually took. For the Raspberry 3b I got a value of 49ms.
> > Indeed, I've changed the timeout in Commit 26459ab7803a, I've tried to
> > follow what's done in Linux in drivers/usb/dwc2/core.c, see
> > https://elixir.bootlin.com/linux/latest/source/drivers/usb/dwc2/core.c#L385
> > 
> > Turns out I've made a mistake, Linux is using 110 ms and not µs.
> > So maybe we can use 110 * MSECOND ? it will still be greater than what's
> > required for the Raspberry 3b.  In the other hand the wait will stop as
> > soon as the mode is set. it will only make the worst case faster...
> > which is not a big deal.
> 
> I am fine with aligning ourselves with what Linux is doing.
> Can you post that as a separate patch? That way this here can go into
> v2021.05.0 to fix the immediate breakage and yours can go into v2020.06.0,
> which will hopefully afford users some more time to test.

Instead of applying two patches I suggest we go with the following
oneliner which is fine for master.

Sascha

------------------------------8<--------------------------------

>From 9fc2b0364c4b686d110b772be2245be3a513407d Mon Sep 17 00:00:00 2001
From: Sascha Hauer <s.hauer at pengutronix.de>
Date: Fri, 7 May 2021 09:58:43 +0200
Subject: [PATCH] usb: dwc2: Fix wait for mode timeout

The timeout waiting for host mode should be 110ms instead of 110us.
The timeout is the same as in Linux now and the same it was before
fdd30cc251. It takes 49ms to go to host mode on the Raspberry Pi 3b,
so host mode stopped working with 26459ab780 which removed an additional
100ms delay before dwc2_wait_for_mode() was actually called.

Fixes: fdd30cc251 ("usb: dwc2: Rework dwc2_wait_for_mode to use wait_on_timeout")
Fixes: 26459ab780 ("usb: dwc2: Rework wait for host mode during core reset")
Reported-by: Ahmad Fatoum <a.fatoum at pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/usb/dwc2/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
index 5d04a07b03..8a78d8199e 100644
--- a/drivers/usb/dwc2/core.c
+++ b/drivers/usb/dwc2/core.c
@@ -688,7 +688,7 @@ int dwc2_get_dr_mode(struct dwc2 *dwc2)
  */
 void dwc2_wait_for_mode(struct dwc2 *dwc2, bool host_mode)
 {
-	unsigned int timeout = 110 * USECOND;
+	unsigned int timeout = 110 * MSECOND;
 	int ret;
 
 	dev_vdbg(dwc2->dev, "Waiting for %s mode\n",
-- 
2.29.2

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