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

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Hi,

> From: Rob Herring
> Sent: Friday, April 22, 2016 10:29 PM
> 
> 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.

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.

Best regards,
Yoshihiro Shimoda

> Rob
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