drm/msm/dsi: hs_zero timing

Hai Li hali at codeaurora.org
Wed Aug 26 10:49:47 PDT 2015

Thanks Werner to test it out. I will focus on the dphy timing calculation then.


It’s better to avoid discussing the excel formula publicly. :)






From: Werner Johansson [mailto:werner.johansson at gmail.com] 
Sent: Wednesday, August 26, 2015 1:39 PM
To: Hai Li
Cc: Rob Clark; werner.johansson at sonymobile.com; dri-devel at lists.freedesktop.org
Subject: RE: drm/msm/dsi: hs_zero timing


On Aug 26, 2015 08:34, "Hai Li" <hali at codeaurora.org <mailto:hali at codeaurora.org> > wrote:
> Hi Werner,
> Thanks for sharing this. The DPHY timings in downstream dtsi are exactly the same as the excel calculation, but slightly different from the output of drm code as you posted. (e.g hs_zero is 116 vs 118)
> I think it is caused by some precision loss during driver calculation, but I need to double check.
> Could you help to try configuring the same DPHY timings as downstream, but leave the values in  DSIPHY_LNx_CFG4 as is, to see if it works?

116 to hs_zero works fine without any other changes (only 118 and every eighth number up and down from there fails with this panel timing), so if we can do something to make sure we hit a working value for hs_zero without touching anything else that would be great! 

Thanks for checking the timings and let me know if you want me to test anything else. Is the excel formula considered public so we can discuss it here? 


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