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

[Felipe Balbi <felipe.balbi@linux.intel.com>]

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Hi,

Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> writes:
>> > Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> 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@vger.kernel.org> # v3.17+
>> >> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
>> >> ---
>> >>  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.
>
> I could fix this in kconfig like the followings:
>
> diff --git a/arch/arm/mach-shmobile/Kconfig b/arch/arm/mach-shmobile/Kconfig
> index f2bc5c3..905d1d2 100644
> --- a/arch/arm/mach-shmobile/Kconfig
> +++ b/arch/arm/mach-shmobile/Kconfig
> @@ -46,6 +46,7 @@ menuconfig ARCH_RENESAS
>  	select PINCTRL
>  	select ARCH_REQUIRE_GPIOLIB
>  	select ZONE_DMA if ARM_LPAE
> +	select USB_XHCI_RCAR if USB_XHCI_HCD
>  
>  if ARCH_RENESAS
>  
> diff --git a/arch/arm64/Kconfig.platforms b/arch/arm64/Kconfig.platforms
> index efa77c1..010d2b7 100644
> --- a/arch/arm64/Kconfig.platforms
> +++ b/arch/arm64/Kconfig.platforms
> @@ -105,6 +105,7 @@ config ARCH_RENESAS
>  	select PM
>  	select PM_GENERIC_DOMAINS
>  	select RENESAS_IRQC
> +	select USB_XHCI_RCAR if USB_XHCI_HCD
>  	help
>  	  This enables support for the ARMv8 based Renesas SoCs.
>
> If this is acceptable, I will send each patch to arm / arm64.

I'm okay with that, not sure what the ARM folks will think ;-)

-- 
balbi

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