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From: Rob Kramer <rob@solution-space.com>
To: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: Troubleshooting LVDS on GM45 (kernel 4.5.0)
Date: Tue, 5 Apr 2016 12:07:58 +0800	[thread overview]
Message-ID: <57033A1E.2000605@solution-space.com> (raw)
In-Reply-To: <20160404145826.GH4329@intel.com>

On 04/04/2016 10:58 PM, Ville Syrjälä wrote:
>
>> Since this VBT mode is probably junk anyway, I commented out the
>> if-statement that selects it (in intel_lvds.c), so that the code will
>> pick the mode as set by BIOS. The result is much better, I actually get
>> proper looking output! X also runs well on top of that.
>>
>> There are still several errors in the log file though (probably caused
>> by my little hack), see here: http://pastebin.com/UbCjizSV.
>>
>> Is using the mode as set up by BIOS the way to go for LVDS? If so, is
>> there a module parameter that can force this, or force the bogus VBT to
>> be disregarded?
> Can you provide a dump of /sys/kernel/debug/dri/0/i915_opregion ?
>
> Maybe file a bug in bugs.freedesktop.org and attach it (and the dmesg
> logs you already have) there so we don't lose these.

Sure! I added the opregion blob to the newly opened bug here: 
https://bugs.freedesktop.org/show_bug.cgi?id=94825

> You also said you can choose the panel type in the BIOS? Does it have
> some predefined set of panels or something? I would have assumed
> changing that might patch the VBT to point at the correct timings.
Yes, there's a list of modes, and the correct one is selected. I've 
added an image to the bug entry. I don't know if the 1024x768 mode 
mentioned in the boot log is the same as the 1024x768 mode in that bios 
list, or why only that mode is found..

I assume that the 1920x1080@148.5M mode was added by the vendor of the 
display set to match the panel that they use.

Cheers,

      Rob


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  reply	other threads:[~2016-04-05  4:08 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-01  4:49 Troubleshooting LVDS on GM45 Rob Kramer
2016-04-01  8:01 ` Jani Nikula
2016-04-01  8:11   ` Rob Kramer
2016-04-01 10:07 ` Troubleshooting LVDS on GM45 (kernel 4.5.0) Rob Kramer
2016-04-01 11:11   ` Jani Nikula
2016-04-04  3:14     ` Rob Kramer
2016-04-04 14:58       ` Ville Syrjälä
2016-04-05  4:07         ` Rob Kramer [this message]
2016-04-01 15:37 ` [PATCH 1/2] drm/i915: Read timings from the correct transcoder in intel_crtc_mode_get() ville.syrjala
2016-04-01 15:37   ` [PATCH 2/2] drm/i915: Use intel_get_pipe_timings() and intel_mode_from_pipe_config() " ville.syrjala
2016-04-01 18:48     ` [PATCH v2 " ville.syrjala
2016-04-13 12:08       ` Ville Syrjälä
2017-09-25 19:19       ` Chris Wilson
2017-10-09 16:18         ` Ville Syrjälä
2017-10-09 16:24           ` Chris Wilson
2017-10-09 16:48             ` Ville Syrjälä
2017-09-25 14:18   ` [Intel-gfx] [PATCH 1/2] drm/i915: Read timings from the correct transcoder " Chris Wilson
2016-04-01 16:44 ` ✗ Fi.CI.BAT: warning for series starting with [1/2] " Patchwork
2016-04-01 17:14   ` Ville Syrjälä

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