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Linux Kernel development collaboration
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EDID read problems #27

Closed tomba closed 4 years ago

tomba commented 5 years ago

There are many cases where EDID reading fails.

One of them is with this display https://www.gechic.com/en-portable-touch-monitor-onlap1303i-view.html using their DP cable https://store.gechic.com/on-lap-proprietary-mini-displayport-cable-1-2m/

The EDID read never succeeds.

Another is with my HP monitor, when using DP->hdmi adapter. Here the failures are more random, but it's quite easy to get the following by inserting the adapter's cable and quickly running kmstest:

[ 2813.811345] cdns-mhdp a000000.dp-bridge: [drm:cdns_mhdp_get_edid_block [mhdp8546]] *ERROR* get block[0] edid failed: -22
[ 2813.822336] cdns-mhdp a000000.dp-bridge: [drm:cdns_mhdp_get_modes [mhdp8546]] *ERROR* Failed to read EDID
[ 2813.847955] cdns-mhdp a000000.dp-bridge: [drm:mhdp_transfer [mhdp8546]] *ERROR* Failed to read DPCD
tomba commented 4 years ago

I don't have the custom DP cable for the gechic display, but I have not seen EDID failures with my HP monitor. So closing this.