Date: Thu, 22 May 2014 23:15:53 +0900 (JST) From: SAITOU Toshihide <toshi@ruby.ocn.ne.jp> To: ian@FreeBSD.org Cc: freebsd-arm@FreeBSD.org Subject: Re: BBB MMC / SD detection instability with U-Boot 2014.04 (CPU 1GHz) Message-ID: <20140522.231553.186386229.toshi@ruby.ocn.ne.jp> In-Reply-To: <1400765234.1152.224.camel@revolution.hippie.lan> References: <CADH-AwGb36EUknNofdch1Q4Pn8GAN%2BEp9SdiJ_f7Q2v9e4kW1g@mail.gmail.com> <20140522.204656.144162099.toshi@ruby.ocn.ne.jp> <1400765234.1152.224.camel@revolution.hippie.lan>
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In message: <1400765234.1152.224.camel@revolution.hippie.lan>
Ian Lepore <ian@FreeBSD.org> writes:
> 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?
I will try ti_prcm_clk_enable() at the weekend. But someone's report
would be appriciated because I remove the src and svn up now.
--
SAITOU Toshihide
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