Date: Thu, 22 May 2014 07:27:14 -0600 From: Ian Lepore <ian@FreeBSD.org> To: SAITOU Toshihide <toshi@ruby.ocn.ne.jp> Cc: freebsd-arm@FreeBSD.org Subject: Re: BBB MMC / SD detection instability with U-Boot 2014.04 (CPU 1GHz) Message-ID: <1400765234.1152.224.camel@revolution.hippie.lan> In-Reply-To: <20140522.204656.144162099.toshi@ruby.ocn.ne.jp> References: <20140521.214356.02299991.toshi@ruby.ocn.ne.jp> <20140522.002051.68155865.toshi@ruby.ocn.ne.jp> <CADH-AwGb36EUknNofdch1Q4Pn8GAN%2BEp9SdiJ_f7Q2v9e4kW1g@mail.gmail.com> <20140522.204656.144162099.toshi@ruby.ocn.ne.jp>
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On Thu, 2014-05-22 at 20:46 +0900, SAITOU Toshihide wrote: > In message: <CADH-AwGb36EUknNofdch1Q4Pn8GAN+Ep9SdiJ_f7Q2v9e4kW1g@mail.gmail.com> > Winston Smith <smith.winston.101@gmail.com> writes: > > On Wed, May 21, 2014 at 11:20 AM, SAITOU Toshihide <toshi@ruby.ocn.ne.jp> wrote: > >> If abort like > >> > >> musbotg0: TI AM335X USBSS v0.0.13 > >> Fatal kernel mode data abort: 'External Non-Linefetch Abort (S)' > >> trapframe: 0xc0a2eb60 > > > > I see this with the 1Ghz uboot, it occurs about 50% of the time, see: > > > > http://comments.gmane.org/gmane.os.freebsd.devel.arm/8200 > > Although it is an ad hoc workaround but ``usb start'' at u-boot command > prompt (someone mentioned before) or add device_printf("!\n") before > ``rev = USBSS_READ4(sc, USBSS_REVREG);'' in the musbotg_attach of > am335x_usbss.c prevent this panic for me. An 'external non-linefetch abort' on a TI chip usually means that the clocks for a device never got turned on and you attempted to read or write a register in that device. If 'usb start' makes the problem go away, that tends to confirm that thought. The thing is, I don't understand why adding a printf to the code with no other changes would help in any way. I though maybe it was adding some delay to allow the clock-start call to take effect, but the clock enable call is after the USBSS_REVREG read, and that seems wrong. Does it fix the problem to move the ti_prcm_clk_enable() call to be before the USBSS_REVREG read in attach? -- Ian
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