RE: [PATCH] usb: dwc2: Read GNPTXFSIZ when in forced HOST mode.

[Paul Zimmerman]

> From: dianders@xxxxxxxxxx [mailto:dianders@xxxxxxxxxx] On Behalf Of Doug Anderson
> Sent: Thursday, August 07, 2014 5:12 PM
> 
> On Thu, Aug 7, 2014 at 1:18 PM, Paul Zimmerman
> <Paul.Zimmerman@xxxxxxxxxxxx> wrote:
> >> From: Doug Anderson [mailto:dianders@xxxxxxxxxxxx]
> >> Sent: Thursday, August 07, 2014 12:48 PM
> >>
> >> The documentation for GNPTXFSIZ says that "For host mode, this field
> >> is always valid."  Since we're already switching to host mode for
> >> HPTXFSIZ, let's also read GNPTXFSIZ in host mode.
> >>
> >> On an rk3288 SoC, without this change we see this at bootup:
> >>   dwc2 ff580000.usb: gnptxfsiz=00100400
> >>   dwc2 ff580000.usb: 128 invalid for host_nperio_tx_fifo_size. Check HW configuration.
> >>
> >> After this change we see:
> >>   dwc2 ff580000.usb: gnptxfsiz=04000400
> >>
> >> Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx>
> >> ---
> >>  drivers/usb/dwc2/core.c | 6 +++---
> >>  1 file changed, 3 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/drivers/usb/dwc2/core.c b/drivers/usb/dwc2/core.c
> >> index 27d2c9b..c184ed43 100644
> >> --- a/drivers/usb/dwc2/core.c
> >> +++ b/drivers/usb/dwc2/core.c
> >> @@ -2674,23 +2674,23 @@ int dwc2_get_hwparams(struct dwc2_hsotg *hsotg)
> >>       hwcfg2 = readl(hsotg->regs + GHWCFG2);
> >>       hwcfg3 = readl(hsotg->regs + GHWCFG3);
> >>       hwcfg4 = readl(hsotg->regs + GHWCFG4);
> >> -     gnptxfsiz = readl(hsotg->regs + GNPTXFSIZ);
> >>       grxfsiz = readl(hsotg->regs + GRXFSIZ);
> >>
> >>       dev_dbg(hsotg->dev, "hwcfg1=%08x\n", hwcfg1);
> >>       dev_dbg(hsotg->dev, "hwcfg2=%08x\n", hwcfg2);
> >>       dev_dbg(hsotg->dev, "hwcfg3=%08x\n", hwcfg3);
> >>       dev_dbg(hsotg->dev, "hwcfg4=%08x\n", hwcfg4);
> >> -     dev_dbg(hsotg->dev, "gnptxfsiz=%08x\n", gnptxfsiz);
> >>       dev_dbg(hsotg->dev, "grxfsiz=%08x\n", grxfsiz);
> >>
> >> -     /* Force host mode to get HPTXFSIZ exact power on value */
> >> +     /* Force host mode to get HPTXFSIZ / GNPTXFSIZ exact power on value */
> >>       gusbcfg = readl(hsotg->regs + GUSBCFG);
> >>       gusbcfg |= GUSBCFG_FORCEHOSTMODE;
> >>       writel(gusbcfg, hsotg->regs + GUSBCFG);
> >>       usleep_range(100000, 150000);
> >>
> >> +     gnptxfsiz = readl(hsotg->regs + GNPTXFSIZ);
> >>       hptxfsiz = readl(hsotg->regs + HPTXFSIZ);
> >> +     dev_dbg(hsotg->dev, "gnptxfsiz=%08x\n", gnptxfsiz);
> >>       dev_dbg(hsotg->dev, "hptxfsiz=%08x\n", hptxfsiz);
> >>       gusbcfg = readl(hsotg->regs + GUSBCFG);
> >>       gusbcfg &= ~GUSBCFG_FORCEHOSTMODE;
> >
> > Nice! I wonder if this is a bug in the original driver, and they
> > actually meant to read this register instead of HPTXFSIZ? Well, it
> > doesn't really matter I guess.
> >
> > Acked-by: Paul Zimmerman <paulz@xxxxxxxxxxxx>
> >
> > You may want to resend this to Greg after -rc1 is out and he reopens
> > his usb-next tree.
> 
> Thanks!
> 
> ...do you think this is a fix that needs to go in for 3.17?  Is it
> affecting anyone there?

I don't think so. It only has an effect if the controller starts up in
peripheral mode and then later switches to host mode, right? I think
yours is the first dwc2 platform in the kernel with that capability.

-- 
Paul