This is a note to let you know that I've just added the patch titled
usb: dwc3: core: defer probe on ulpi_read_id timeout
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-dwc3-core-defer-probe-on-ulpi_read_id-timeout.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 63130462c919ece0ad0d9bb5a1f795ef8d79687e Mon Sep 17 00:00:00 2001
From: Ferry Toth <ftoth@xxxxxxxxxxxxxx>
Date: Mon, 5 Dec 2022 21:15:27 +0100
Subject: usb: dwc3: core: defer probe on ulpi_read_id timeout
From: Ferry Toth <ftoth@xxxxxxxxxxxxxx>
commit 63130462c919ece0ad0d9bb5a1f795ef8d79687e upstream.
Since commit 0f0101719138 ("usb: dwc3: Don't switch OTG -> peripheral
if extcon is present"), Dual Role support on Intel Merrifield platform
broke due to rearranging the call to dwc3_get_extcon().
It appears to be caused by ulpi_read_id() masking the timeout on the first
test write. In the past dwc3 probe continued by calling dwc3_core_soft_reset()
followed by dwc3_get_extcon() which happend to return -EPROBE_DEFER.
On deferred probe ulpi_read_id() finally succeeded. Due to above mentioned
rearranging -EPROBE_DEFER is not returned and probe completes without phy.
On Intel Merrifield the timeout on the first test write issue is reproducible
but it is difficult to find the root cause. Using a mainline kernel and
rootfs with buildroot ulpi_read_id() succeeds. As soon as adding
ftrace / bootconfig to find out why, ulpi_read_id() fails and we can't
analyze the flow. Using another rootfs ulpi_read_id() fails even without
adding ftrace. We suspect the issue is some kind of timing / race, but
merely retrying ulpi_read_id() does not resolve the issue.
As we now changed ulpi_read_id() to return -ETIMEDOUT in this case, we
need to handle the error by calling dwc3_core_soft_reset() and request
-EPROBE_DEFER. On deferred probe ulpi_read_id() is retried and succeeds.
Fixes: ef6a7bcfb01c ("usb: ulpi: Support device discovery via DT")
Cc: stable@xxxxxxxxxxxxxxx
Acked-by: Thinh Nguyen <Thinh.Nguyen@xxxxxxxxxxxx>
Signed-off-by: Ferry Toth <ftoth@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20221205201527.13525-3-ftoth@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/dwc3/core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -801,8 +801,13 @@ static int dwc3_core_init(struct dwc3 *d
if (!dwc->ulpi_ready) {
ret = dwc3_core_ulpi_init(dwc);
- if (ret)
+ if (ret) {
+ if (ret == -ETIMEDOUT) {
+ dwc3_core_soft_reset(dwc);
+ ret = -EPROBE_DEFER;
+ }
goto err0;
+ }
dwc->ulpi_ready = true;
}
Patches currently in stable-queue which might be from ftoth@xxxxxxxxxxxxxx are
queue-4.14/usb-dwc3-core-defer-probe-on-ulpi_read_id-timeout.patch
