Attachment 44442 Details for Bug 34682 – 24 bit LVDS control / support w/ whitespace fixes

[patch] 24 bit LVDS control / support w/ whitespace fixes

0001--drm-i915-Implement-direct-support-for-24-bit-LVD.patch (text/plain), 1.94 KB, created by Mike Isely on 2011-03-14 09:01:57 UTC

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Creator: Mike Isely

Created: 2011-03-14 09:01:57 UTC

Size: 1.94 KB

patch

obsolete

>From ba69e88573de637985e9d0425cfa040912f88972 Mon Sep 17 00:00:00 2001
>From: Mike Isely <isely@pobox.com>
>Date: Mon, 14 Mar 2011 10:41:01 -0500
>Subject: [PATCH] [drm/i915] - Implement direct support for 24 bit LVDS pixel format
>
>LVDS digital data can be formatted as 18 bits/pixel or one of two
>24 bits/pixel possibilities.  All are incompatible with one another,
>so the GPU's LVDS output has to be configured to match the format
>expected by the display device.
>
>In many (most) cases this is generally not a problem because the LVDS
>device is integral to the processor board (e.g. a laptop) and thus the
>video BIOS already sets this up correctly as part of the boot
>process.  Then the i915 drm simply works with what has been already
>set up.
>
>But there are cases where the LVDS-driven display and the GPU are
>discrete components - this can happen in embedded environments where
>the processor board is a COTS device with its own BIOS and the display
>is added to it later.  In that situation the video BIOS on the
>processor board can't know anything about the LVDS display which leads
>to problems if the pixel format is not 18 bit (usually 18 bit is the
>default).
>
>This patch implements a new kernel option for the i915 kernel module:
>"lvds_24bit".  The default value of zero preserves the previous "don't
>change anything" behavior.  If it is set to "1" or "2" then 24 bit
>format is enabled - the choice between "1" and "2" selects the
>particular 24 bit format.  If it is set to "3" then 24 format is
>specifically disabled, which should be an extremely rare case but is
>included for completeness.
>
>There was a similar patch back in 2008 to support 24 bit LVDS with the
>user-mode xorg intel driver, using a new driver option in the
>xorg.conf file.  However that patch was a casualty of the move to
>kernel mode switching.  This patch implements the same sort of
>solution, just now it's in the kernel drm driver for i915 driven GPUs.
>
>Signed-Off-By: Mike Isely <isely@pobox.com>
>
>-- 
>1.5.6.5
>

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