From 82d753567f6f3bb5059bd18e8fd8aa7915fcbe05 Mon Sep 17 00:00:00 2001 From: Tomeu Vizoso Date: Thu, 8 Dec 2016 14:11:56 +0100 Subject: [PATCH] drm/edid: Don't print an error if the checksum of a CEA block is wrong It's common to share screens within CI labs, and it's also common for KVM switches to alter the contents of the CEA block but leave the checksum outdated. So in this case, print a debug message instead of an error. References: https://bugs.freedesktop.org/show_bug.cgi?id=98228 Cc: Chris Wilson Cc: Tomi Sarvela Cc: intel-gfx@lists.freedesktop.org Signed-off-by: Tomeu Vizoso Tested-by: Jari Tahvanainen Signed-off-by: Daniel Vetter Link: http://patchwork.freedesktop.org/patch/msgid/1481202716-31317-1-git-send-email-tomeu.vizoso@collabora.com --- drivers/gpu/drm/drm_edid.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index c8baab9bee0d..5a3b34a88ac3 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1131,16 +1131,19 @@ bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid, csum = drm_edid_block_checksum(raw_edid); if (csum) { - if (print_bad_edid) { - DRM_ERROR("EDID checksum is invalid, remainder is %d\n", csum); - } - if (edid_corrupt) *edid_corrupt = true; /* allow CEA to slide through, switches mangle this */ - if (raw_edid[0] != 0x02) + if (raw_edid[0] == CEA_EXT) { + DRM_DEBUG("EDID checksum is invalid, remainder is %d\n", csum); + DRM_DEBUG("Assuming a KVM switch modified the CEA block but left the original checksum\n"); + } else { + if (print_bad_edid) + DRM_ERROR("EDID checksum is invalid, remainder is %d\n", csum); + goto bad; + } } /* per-block-type checks */ -- 2.20.1