Paulo Zanoni adf00b26d1 drm/i915: make sure we write all the DIP data bytes ... ... even if the actual infoframe is smaller than the maximum possible size. If we don't write all the 32 DIP data bytes the InfoFrame ECC may not be correctly calculated in some cases (e.g., when changing the port), and this will lead to black screens on HDMI monitors. The ECC value is generated by the hardware. I don't see how this should break anything since we're writing 0 and that should be the correct value, so this patch should be safe. Notice that on IVB and older we actually have 64 bytes available for VIDEO_DIP_DATA, but only bytes 0-31 actually store infoframe data: the others are either read-only ECC values or marked as "reserved". On HSW we only have 32 bytes, and the ECC value is stored on its own separate read-only register. See BSpec. This patch fixes bug #46761, which is marked as a regression introduced by commit 4e89ee174b: drm/i915: set the DIP port on ibx_write_infoframe Before commit 4e89 we were just failing to send AVI infoframes when we needed to change the port, which can lead to black screens in some cases. After commit 4e89 we started sending infoframes, but with a possibly wrong ECC value. After this patch I hope we start sending correct infoframes. Version 2: - Improve commit message - Try to make the code more clear Cc: stable@vger.kernel.org Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=46761 Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com> Reviewed-by: Rodrigo Vivi <rodrigo.vivi@gmail.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>		2012-09-26 09:24:09 +02:00
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drm	drm/i915: make sure we write all the DIP data bytes	2012-09-26 09:24:09 +02:00
stub	i915: select VIDEO_OUTPUT_CONTROL for ACPI_VIDEO	2011-04-13 09:10:25 +10:00
vga	vga_switcheroo: Don't require handler init callback	2012-08-17 17:34:41 -04:00
Makefile	gpu: Add Intel GMA500(Poulsbo) Stub Driver	2010-10-26 11:00:13 +10:00