[PATCH] Revert "drm/amd/display: Program OTG vtotal min/max selectors unconditionally for DCN1+"

[Melissa Wen]

On 07/12, Aurabindo Pillai wrote:
> 
> 
> On 7/12/2023 12:24 PM, Melissa Wen wrote:
> > On 07/12, Pillai, Aurabindo wrote:
> > > [Public]
> > > 
> > > Hi Guilherme,
> > > 
> > > Sorry there was one more patch which I missed to attach. Please add this 3rd patch and retry.
> > > 
> > > Reverting that patch would cause high power consumption on Navi2x GPU also cause hangs on certain multi monitor configurations. With these 3 patches, you're getting the same effect as reverting the aforementioned patches, but it makes the reverted sequence available only for Steam deck hardware.
> > > 
> > 
> > Hi Jay,
> > 
> > Thanks for looking at this issue.
> > 
> > You mention power consumption and multi-monitor configuration issues
> > that can affect a driver if we revert this OTG change, and both sounds
> > quite relevant to me. Can they not affect DCN301 too? Is there something
> > that needs further work so the DCN301 can benefit from this improvement
> > as well?
> > 
> > Also, let us know if we can contribute in any way.
> > 
> 
> Hi Melissa,
> 
> Unfortunately, DCN301 does not support Firmware Assisted Memory Clock
> Switching, which is the feature that gets blocked on Navi2x if we revert the
> patch in question.  This is the feature that enables lower power consumption
> on some multi monitor configurations and high refresh rate single monitor
> configurations.
> 
> Navi2x is configured to use FAMS in the driver, but without this change,
> firmware wont be able to actually enable the feature in DMCUB, which puts
> the driver in a unexpected state. On DCN301, this unexpected state will not
> occur, because there is no FAMS support in driver nor firmware.

Oh, got it. Sounds fine.
Many thanks for explaning the context of this change.

Best Regards,

Melissa

> 
> --
> Jay
> 
> 
> 
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