[Bug 97244] [DP] [SKL] 5k tiled dual DP (two-pipe, two-port) display sync issues

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=97244

--- Comment #60 from Ankit <ankit.k.nautiyal at intel.com> ---
(In reply to Ankit from comment #59)
> Comment on attachment 145267 [details]
> Logs with 5K HPz27q
> 
> I was able to get 5K HPz27q 317b monitor for some time. Below are the
> observation on HPz27q Monitor with two DP cables connected to a KBL machine.

Not KBL but SKL machine. Sorry for the typo.
> 
> *****General Observation*****
> The monitor settings has two modes, DP1.0 and DP1.2.
> One of the connector is enumerated as 'tiled' and the other as non tiled.
> 
> The non-tiled connector has modes starting from 2K and below, and the tiled
> connector has just one mode 2560x2880.
> No corruption observed in this case.
> 
> In case of DP2.0 two connectors are enumerated, both tiled.
> One connector has modes from 3849x2160 and below. 2560x2880 being preferred
> mode.
> The other has 2560x2880 mode, also preferred.
> 
> The issue is seen when both the modes selected are 2560x2880. This results
> like two halves of screens not in sync.
> 
> *****Experiment with different patches*****
> 
> I collected logs in 3 cases:
> 1. Without any patch (vanilla)
> 2. With patch to prune the 2560x2880 mode, only for tile with HLOC and VLOC
> as 0.
> 3. With a patch to force the connector property as 'false'
> 
> Logs for which are attached.
> Note 1: I had changed the display info to provide the Tile information, in
> case the connector 'has_tile' is true.
> Note 2: I had checked and collected logs with single display and also with
> dual display configuration with DP1.2 monitor settings.
> Note 3: The mode is changed using xrandr.
>  
> case1:
> -Without any patch : 2560x2880 modeset on both connectors causes corruption.
> 
> case2:
> -With 2560x2880 mode pruned for one of the tile : Only one of the connector
> shows 2560x2880 mode.
> 2560x2880 modeset on any the remaining connector resulted in blank screen.
> Any other modeset works.
> 
> case3:
> -With has_tile connector property forcibly reset : The connector listed as
> not tiled but still, 2560x2880 modeset on any the connectors causes blank
> screen.
> Any other modeset works.
> 
> To summarize, pruning on just one tiled connector does not solve the issue,
> if we need to prune, we need to do it for both the connectors.
> Secondly, the forcible setting of has_tile = 'false' also, does not help,
> and resulted in blank screen when 2560x2880 mode is applied.
> So IMHO if we need to prune the mode 2560x2880, we need to prune it for both
> the connectors.

(In reply to Ankit from comment #59)
> Comment on attachment 145267 [details]
> Logs with 5K HPz27q
> 
> I was able to get 5K HPz27q 317b monitor for some time. Below are the
> observation on HPz27q Monitor with two DP cables connected to a KBL machine.
> 
> *****General Observation*****
> The monitor settings has two modes, DP1.0 and DP1.2.
> One of the connector is enumerated as 'tiled' and the other as non tiled.
> 
> The non-tiled connector has modes starting from 2K and below, and the tiled
> connector has just one mode 2560x2880.
> No corruption observed in this case.
> 
> In case of DP2.0 two connectors are enumerated, both tiled.
> One connector has modes from 3849x2160 and below. 2560x2880 being preferred
> mode.
> The other has 2560x2880 mode, also preferred.
> 
> The issue is seen when both the modes selected are 2560x2880. This results
> like two halves of screens not in sync.
> 
> *****Experiment with different patches*****
> 
> I collected logs in 3 cases:
> 1. Without any patch (vanilla)
> 2. With patch to prune the 2560x2880 mode, only for tile with HLOC and VLOC
> as 0.
> 3. With a patch to force the connector property as 'false'
> 
> Logs for which are attached.
> Note 1: I had changed the display info to provide the Tile information, in
> case the connector 'has_tile' is true.
> Note 2: I had checked and collected logs with single display and also with
> dual display configuration with DP1.2 monitor settings.
> Note 3: The mode is changed using xrandr.
>  
> case1:
> -Without any patch : 2560x2880 modeset on both connectors causes corruption.
> 
> case2:
> -With 2560x2880 mode pruned for one of the tile : Only one of the connector
> shows 2560x2880 mode.
> 2560x2880 modeset on any the remaining connector resulted in blank screen.
> Any other modeset works.
> 
> case3:
> -With has_tile connector property forcibly reset : The connector listed as
> not tiled but still, 2560x2880 modeset on any the connectors causes blank
> screen.
> Any other modeset works.
> 
> To summarize, pruning on just one tiled connector does not solve the issue,
> if we need to prune, we need to do it for both the connectors.
> Secondly, the forcible setting of has_tile = 'false' also, does not help,
> and resulted in blank screen when 2560x2880 mode is applied.
> So IMHO if we need to prune the mode 2560x2880, we need to prune it for both
> the connectors.

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