Hi Shimoda-san,
Thanks for your patch!
On Fri, Jan 17, 2020 at 11:54 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> Since EHCI/OHCI controllers on R-Car Gen3 SoCs are possible to
> be getting stuck very rarely after a full/low usb device was
> disconnected. To detect/recover from such a situation, the controllers
> require a special way which poll the EHCI PORTSC register and changes
> the OHCI functional state.
Oops... Is this limited to the EHCI/OHCI implementation on R-Car Gen3?
Or can it happen on any EHCI/OHCI controller?
> --- a/Documentation/devicetree/bindings/usb/generic-ehci.yaml
> +++ b/Documentation/devicetree/bindings/usb/generic-ehci.yaml
> @@ -63,6 +63,11 @@ properties:
> description:
> Set this flag to force EHCI reset after resume.
>
> + needs-polling-to-avoid-stuck:
> + $ref: /schemas/types.yaml#/definitions/flag
> + description:
> + Set this flag to avoid getting EHCI stuck.
> +
> companion:
> $ref: /schemas/types.yaml#/definitions/phandle
> description:
If this issue is specific to the EHCI/OHCI implementation on R-Car Gen3,
I don't think this is the best solution to handle it.
It might be better to add family/SoC-specific compatible values for the
EHCI/OHCI controllers in R-Car Gen3 SoCs, cfr. the (undocumented)
"ibm,usb-ehci-440epx" and "allwinner,sun4i-a10-ehci" compatible values
in the example in the DT bindings file (probably we should have done so
from the start, like for all other devices).
Then the driver can handle the issue based on the compatible value.
Besides, what about DT backwards compatibility?
To enable this quirk handling, the DT must be updated first.
This is true for solutions based on either a DT property or on a
different compatible value.
Of course, you can always use soc_device_match()...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
