On 8/2/2022 9:40 PM, Johan Hovold wrote:
On Fri, Jul 15, 2022 at 06:51:52PM +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.
Fixes: 649f5c842ba3 ("usb: dwc3: core: Host wake up support from system suspend")
Signed-off-by: Krishna Kurapati <quic_kriskura@xxxxxxxxxxx>
---
v2: Set return value to EPROBE_DEFER to drop reference to dwc3 node
drivers/usb/dwc3/dwc3-qcom.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
index 7703655..6676b39 100644
--- a/drivers/usb/dwc3/dwc3-qcom.c
+++ b/drivers/usb/dwc3/dwc3-qcom.c
@@ -722,6 +722,9 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev)
dev_err(dev, "failed to get dwc3 platform device\n");
}
+ if (!qcom->dwc3->dev.driver)
+ ret = -EPROBE_DEFER;
+
node_put:
of_node_put(dwc3_np);
NAK.
We should not be adding hacks like this to the driver.
There are other ways to avoid this, but please take a look at the
following series which makes the problem identified by this patch go
away first:
https://lore.kernel.org/all/20220802151404.1797-1-johan+linaro@xxxxxxxxxx
Johan
Hi Johan,
Thanks for the review and patches. Agreed that if we are moving
wakeup-source to glue driver, dwc3 probe getting deferred won't be an issue.
Regards,
Krishna,
