On Wed, Feb 10, 2021 at 12:56:59PM -0600, Bjorn Andersson wrote:

On Wed 10 Feb 12:40 CST 2021, Serge Semin wrote:

quoted

On Wed, Feb 10, 2021 at 12:17:27PM -0600, Rob Herring wrote:

quoted

On Wed, Feb 10, 2021 at 11:29 AM Serge Semin
[off-list ref] wrote:

quoted

In accordance with the USB HCD/DRD schema all the USB controllers are
supposed to have DT-nodes named with prefix "^usb(@.*)?".  Since the
existing DT-nodes will be renamed in a subsequent patch let's first make
sure the DWC3 Qualcomm driver supports them and second falls back to the
deprecated naming so not to fail on the legacy DTS-files passed to the
newer kernels.

Signed-off-by: Serge Semin <redacted>
Reviewed-by: Bjorn Andersson <redacted>
---
 drivers/usb/dwc3/dwc3-qcom.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/dwc3/dwc3-qcom.c b/drivers/usb/dwc3/dwc3-qcom.c
index c703d552bbcf..49ad8d507d37 100644
--- a/drivers/usb/dwc3/dwc3-qcom.c
+++ b/drivers/usb/dwc3/dwc3-qcom.c

@@ -630,7 +630,8 @@ static int dwc3_qcom_of_register_core(struct platform_device *pdev)
        struct device           *dev = &pdev->dev;
        int                     ret;

-       dwc3_np = of_get_child_by_name(np, "dwc3");
+       dwc3_np = of_get_child_by_name(np, "usb") ?:
+                 of_get_child_by_name(np, "dwc3");

quoted

Is there some reason using compatible instead wouldn't work here?

I don't know for sure. The fix has been requested in the framework of
this discussion:
https://lore.kernel.org/linux-usb/20201020115959.2658-30-Sergey.Semin@baikalelectronics.ru/#t (local)
by the driver maintainer Bjorn. To get a firm answer it's better to
have him asked.

My feedback was simply that it has to catch both cases, I didn't
consider the fact that we have a compatible to match against.

quoted

As I see it having of_get_compatible_child() utilized
here would also work. At least for the available in kernel dt-files.
See the affected dts-es in:
https://lore.kernel.org/linux-usb/20210210172850.20849-11-Sergey.Semin@baikalelectronics.ru/ (local)

A problem may happen if some older versions of DTS-es had another
compatible string in the dwc3 sub-node...

Afaict all Qualcomm dts files has "snps,dwc3", so you can match against
that instead.

Ok then. I'll replace of_get_child_by_name() here with
of_get_compatible_child() matching just against "snps,dwc3" in v7. Can you
confirm that noone ever had a Qcom-based hardware described with dts having
the "synopsys,dwc3" compatible used as the DWC USB3 sub-node here? That
string has been marked as deprecated recently because the vendor-prefix
was changed sometime ago, but the original driver still accept it.

Alternatively to be on a safe side we could match against both
compatibles here as Rob suggests. What do you think?

-Sergey

Regards,
Bjorn