On Wed, Feb 08, 2017 at 01:19:23PM +0000, Tahvanainen, Jari wrote:
> I applied this change on the couple-days old drm-tip, and was not able to get
> any "EDID checksum is invalid" messages with it on my SKL. Without this patch
> I could generate the ERROR quite easily by switching the outputs and displays
> manually.
> I don't know if this hides something that it should not but it seem to work
> for the problem related the noise on Patchwork CI execution caused by these
> EDID checksum is invalid messages.
>
> Tested-by: Jari Tahvanainen <[email protected]>
>
> -----Original Message-----
> From: Tomeu Vizoso [mailto:[email protected]]
> Sent: Thursday, December 8, 2016 3:12 PM
> To: [email protected]
> Cc: Tomeu Vizoso <[email protected]>; Tomi Sarvela
> <[email protected]>; [email protected]; David Airlie
> <[email protected]>; [email protected]; Daniel Vetter
> <[email protected]>
> Subject: 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 outdated.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 <[email protected]>
> Cc: Tomi Sarvela <[email protected]>
> Cc: [email protected]
> Signed-off-by: Tomeu Vizoso <[email protected]>
Applied to drm-misc, thanks.
-Daniel
> ---
> 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
> 6798c3ad9d53..db79bc949216 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -1128,16 +1128,19 @@ 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 */
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--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
