svn commit: r276249 - head/sys/arm/ti/am335x

[Adrian Chadd]

Holy crap, great catch!



-adrian


On 26 December 2014 at 09:45, Luiz Otavio O Souza <loos at freebsd.org> wrote:
> Author: loos
> Date: Fri Dec 26 17:45:49 2014
> New Revision: 276249
> URL: https://svnweb.freebsd.org/changeset/base/276249
>
> Log:
>   Fix the musb initialization sequence on AM335x.
>
>   According to http://e2e.ti.com/support/arm/sitara_arm/f/791/t/210729 the
>   USB reset pulse has an undocumented duration of 200ns and during this
>   period the module must not be acessed.
>
>   We wait for 100us to take into account for some imprecision of the early
>   DELAY() loop.
>
>   This fixes the eventual 'External Non-Linefetch Abort (S)' that happens at
>   boot while resetting the musb subsystem.
>
>   While here, enable the USB subsystem clock before the first access.
>
>   Discussed with:       ian, adrian
>   MFC after:            2 weeks
>
> Modified:
>   head/sys/arm/ti/am335x/am335x_usbss.c
>
> Modified: head/sys/arm/ti/am335x/am335x_usbss.c
> ==============================================================================
> --- head/sys/arm/ti/am335x/am335x_usbss.c       Fri Dec 26 15:04:03 2014        (r276248)
> +++ head/sys/arm/ti/am335x/am335x_usbss.c       Fri Dec 26 17:45:49 2014        (r276249)
> @@ -288,21 +288,30 @@ musbotg_attach(device_t dev)
>                 return (ENXIO);
>         }
>
> +       /* Enable device clocks. */
> +       ti_prcm_clk_enable(MUSB0_CLK);
> +
>         /*
> -        * Reset USBSS, USB0 and USB1
> +        * Reset USBSS, USB0 and USB1.
> +        * The registers of USB subsystem must not be accessed while the
> +        * reset pulse is active (200ns).
>          */
> +       USBSS_WRITE4(sc, USBSS_SYSCONFIG, USBSS_SYSCONFIG_SRESET);
> +       DELAY(100);
> +       i = 10;
> +       while (USBSS_READ4(sc, USBSS_SYSCONFIG) & USBSS_SYSCONFIG_SRESET) {
> +               DELAY(100);
> +               if (i-- == 0) {
> +                       device_printf(dev, "reset timeout.\n");
> +                       return (ENXIO);
> +               }
> +       }
> +
> +       /* Read the module revision. */
>         rev = USBSS_READ4(sc, USBSS_REVREG);
>         device_printf(dev, "TI AM335X USBSS v%d.%d.%d\n",
>             (rev >> 8) & 7, (rev >> 6) & 3, rev & 63);
>
> -       ti_prcm_clk_enable(MUSB0_CLK);
> -
> -       USBSS_WRITE4(sc, USBSS_SYSCONFIG,
> -           USBSS_SYSCONFIG_SRESET);
> -       while (USBSS_READ4(sc, USBSS_SYSCONFIG) &
> -           USBSS_SYSCONFIG_SRESET)
> -               ;
> -
>         err = bus_setup_intr(dev, sc->sc_irq_res[0],
>             INTR_TYPE_BIO | INTR_MPSAFE,
>             NULL, (driver_intr_t *)musbotg_usbss_interrupt, sc,
>