Re: [PATCH v2] usb: host: xhci-rcar: Avoid long wait in xhci_reset()

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On Fri, Apr 22, 2016 at 4:36 AM, Felipe Balbi
<felipe.balbi@xxxxxxxxxxxxxxx> wrote:
>
> Hi,
>
> Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx> writes:
>> The firmware of R-Car USB 3.0 host controller will control the reset.
>> So, if the xhci driver doesn't do firmware downloading (e.g. kernel
>> configuration is CONFIG_USB_XHCI_PLATFORM=y and CONFIG_USB_XHCI_RCAR
>> is not set), the reset of USB 3.0 host controller doesn't work
>> correctly. Then, the host controller will cause long wait in
>> xhci_reset() because the CMD_RESET bit of op_regs->command is not
>> cleared for 10 seconds.
>>
>> So, this patch modifies the xhci_rcar_init_quirk() in xhci-rcar.h
>> to exit the probe function immediately.
>>
>> Fixes: 4ac8918f3a7 (usb: host: xhci-plat: add support for the R-Car H2 and M2 xHCI controllers)
>> Cc: <stable@xxxxxxxxxxxxxxx> # v3.17+
>> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
>> ---
>>  Changes from v1:
>>   - Revise the commit log.
>>     (http://www.spinics.net/lists/stable/msg130007.html)
>>
>>  drivers/usb/host/xhci-rcar.h | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/host/xhci-rcar.h b/drivers/usb/host/xhci-rcar.h
>> index 2941a25..2afed68 100644
>> --- a/drivers/usb/host/xhci-rcar.h
>> +++ b/drivers/usb/host/xhci-rcar.h
>> @@ -24,7 +24,11 @@ static inline void xhci_rcar_start(struct usb_hcd *hcd)
>>
>>  static inline int xhci_rcar_init_quirk(struct usb_hcd *hcd)
>>  {
>> -     return 0;
>> +     /*
>> +      * To avoid wait and timeout in xhci_reset() if CONFIG_XHCI_RCAR is
>> +      * disabled, this function fails.
>> +      */
>> +     return -ENODEV;
>
> okay, if I understood correctly the thing is that you have a kernel
> built with XHCI platform support but without XHCI RCAR support. Then, if
> you run this kernel on RCAR board, you see this CMD_RESET problem,
> right?
>
> Isn't this pointing to the fact that xhci-plat.ko built without RCAR
> isn't exactly compatible with RCAR ?
>
> IOW:
>
> diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
> index 676ea458148b..3e39320564ce 100644
> --- a/drivers/usb/host/xhci-plat.c
> +++ b/drivers/usb/host/xhci-plat.c
> @@ -112,6 +112,7 @@ static const struct of_device_id usb_xhci_of_match[] = {
>         }, {
>                 .compatible = "marvell,armada-380-xhci",
>                 .data = &xhci_plat_marvell_armada,
> +#if IS_ENABLED(CONFIG_USB_XHCI_RCAR)
>         }, {
>                 .compatible = "renesas,xhci-r8a7790",
>                 .data = &xhci_plat_renesas_rcar_gen2,
> @@ -130,6 +131,7 @@ static const struct of_device_id usb_xhci_of_match[] = {
>         }, {
>                 .compatible = "renesas,rcar-gen3-xhci",
>                 .data = &xhci_plat_renesas_rcar_gen3,
> +#endif
>         },
>         {},
>  };
>
> Rob, should we limit compatible flags like this ? Without
> CONFIG_USB_XHCI_RCAR, this driver won't work on RCAR but, as you can
> see, this driver might still work on other non-RCAR platforms.
>
> What's your take on this ?

We should fix this in kconfig to always enable the option when RCAR is
enabled IMO.

Rob
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