From: Jani Nikula <jani.nikula@linux.intel.com>
To: 陳勇秀 <greatshow.chen@gmail.com>, intel-gfx@lists.freedesktop.org
Subject: Re: No display at boot
Date: Tue, 23 Sep 2014 15:41:00 +0300 [thread overview]
Message-ID: <87tx3y5x2b.fsf@intel.com> (raw)
In-Reply-To: <CAJ6_vb3ObrEqhaVO2d8bLaP7=ampF_qGueXYG5T7zQw4bkPjEQ@mail.gmail.com>
On Tue, 23 Sep 2014, 陳勇秀 <greatshow.chen@gmail.com> wrote:
> Hi All,
>
> I am using a baytrail cpu and linux kernel 3.14.7, and will echo some
> message to /dev/tty1 during boot.
>
> There is chance that no display output during boot, but I can use linux via
> ttyS4, the HSUART.
>
> Attached is output of intel_reg_dumper,
> display.fail is register dump that no display output.
> display_ok is register dump that display works.
>
> There is difference between:
>
> DPLL_A_MD: 0x60ff2cdf (ok)
> DPLL_A_MD: 0x70ff2ddf (fail)
>
> DPLL_B: 0x60ff2cdf (disabled, dvo, VGA, TV A clock, unknown mode, p1 = 1,
> p2 = 0) (ok)
> DPLL_B: 0x70ff2ddf (disabled, dvo, TV A clock, unknown mode, p1 = 1, p2 =
> 0, using FPx1!) (fail)
>
> The bios dump is also attached. How do I read the bios dump file?
>
> The problem can be reproduced even I update kernel to 3.14.18.
>
>
> It's interesting the no display issue never happens if I boot into x-window
> system.
Please file a bug against DRM/Intel at [1], attach dmesg all the way
from boot to the problem with drm.debug=14 module parameter set.
BR,
Jani.
[1] https://bugs.freedesktop.org/enter_bug.cgi?product=DRI
--
Jani Nikula, Intel Open Source Technology Center
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prev parent reply other threads:[~2014-09-23 12:41 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-23 2:49 No display at boot 陳勇秀
2014-09-23 12:41 ` Jani Nikula [this message]
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