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

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Hi Geert-san,

> From: Geert Uytterhoeven
> Sent: Monday, April 25, 2016 3:58 PM
> 
> Hi Shimoda-san,
> 
> On Mon, Apr 25, 2016 at 4:10 AM, Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@xxxxxxxxxxx> wrote:
> >> 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:
> >> > 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?
> 
> [...]
> 
> >> 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.
> 
> What about enforcing this in a single place instead, i.e. in
> drivers/usb/host/Kconfig?

Thank you for the suggestion. I could make such a patch.
I prefer this than each arm / arm64 patch.

diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
index 3050b18..e9d4dde 100644
--- a/drivers/usb/host/Kconfig
+++ b/drivers/usb/host/Kconfig
@@ -35,6 +35,7 @@ config USB_XHCI_PCI
 
 config USB_XHCI_PLATFORM
 	tristate "Generic xHCI driver for a platform device"
+	select USB_XHCI_RCAR if ARCH_RENESAS
 	---help---
 	  Adds an xHCI host driver for a generic platform device, which
 	  provides a memory space and an irq.
@@ -63,7 +64,7 @@ config USB_XHCI_MVEBU
 
 config USB_XHCI_RCAR
 	tristate "xHCI support for Renesas R-Car SoCs"
-	select USB_XHCI_PLATFORM
+	depends on USB_XHCI_PLATFORM
 	depends on ARCH_RENESAS || COMPILE_TEST
 	---help---
 	  Say 'Y' to enable the support for the xHCI host controller

Best regards,
Yoshihiro Shimoda

> 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
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