Re: [PATCH] usb: dwc3: qcom: Defer dwc3-qcom probe if dwc3 isn't probed properly

From: Krishna Kurapati PSSNV
Date: Thu Jul 14 2022 - 11:25:06 EST

On 7/14/2022 8:31 PM, Greg Kroah-Hartman wrote:
On Thu, Jul 14, 2022 at 08:25:16PM +0530, Krishna Kurapati wrote:
On SC7180 devices, it is observed that dwc3 probing is deferred
because device_links_check_suppliers() finds that '88e3000.phy'
isn't ready yet.

As a part of its probe call, dwc3-qcom driver checks if dwc3 core
is wakeup capable or not. If the dwc3 core is wakeup capable, driver
configures dwc-qcom's power domain to be always ON. Also it configures
dp/dm interrupts accordingly to support wakeup from system suspend.

More info regarding the same can be found at:
commit d9be8d5c5b03 ("usb: dwc3: qcom: Keep power domain on to retain controller status"
commit 6895ea55c385 ("usb: dwc3: qcom: Configure wakeup interrupts during suspend")

In the event, dwc3 probe gets deferred and is processed after dwc3-qcom
probe, driver ends up reading the wakeup capability of dwc3 core as false
leading to instability in suspend/resume path.

To avoid this scenario, ensure dwc3_probe is successful by checking
if appropriate driver is assigned to it or not after the of_platform_populate
call. If it isn't then defer dwc3-qcom probe as well.

Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
drivers/usb/dwc3/dwc3-qcom.c | 3 +++
1 file changed, 3 insertions(+)
I got 2 different copies of this change, what's the difference?


greg k-h
Sorry Greg, My bad, I thought the mail sending failed the first time. So I sent the same patch second time. Sorry for the confusion.