Date: Fri, 26 Dec 2014 09:59:01 -0800 From: Adrian Chadd <adrian@freebsd.org> To: Luiz Otavio O Souza <loos@freebsd.org> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r276249 - head/sys/arm/ti/am335x Message-ID: <CAJ-Vmo=ra9f4-6XQyEJ%2B_5oELqNoXSdFNG83N3-D3gZ=Bu0TKg@mail.gmail.com> In-Reply-To: <201412261745.sBQHjoMj029672@svn.freebsd.org> References: <201412261745.sBQHjoMj029672@svn.freebsd.org>
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Holy crap, great catch! -adrian On 26 December 2014 at 09:45, Luiz Otavio O Souza <loos@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, >
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