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[Ville Syrjälä]

Subject: Re: [PATCH 04/12] drm: Nuke mode->vrefresh
Message-ID: <20200226115708.GH13686 at intel.com>
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User-Agent: Mutt/1.10.1 (2018-07-13)

On Tue, Feb 25, 2020 at 10:52:25PM +0100, Linus Walleij wrote:
> On Tue, Feb 25, 2020 at 8:27 PM Ville Syrjälä
> <ville.syrjala at linux.intel.com> wrote:
> 
> > OK, so I went ahead a wrote a bit of cocci [1] to find the bad apples.
> 
> That's impressive :D
> 
> > Unfortunately it found a lot of strange stuff:
> 
> I will answer for the weirdness I caused.
> 
> I have long suspected that a whole bunch of the "simple" displays
> are not simple but contains a display controller and memory.
> That means that the speed over the link to the display and
> actual refresh rate on the actual display is asymmetric because
> well we are just updating a RAM, the resolution just limits how
> much data we are sending, the clock limits the speed on the
> bus over to the RAM on the other side.

IMO even in command mode mode->clock should probably be the actual
dotclock used by the display. If there's another clock for the bus
speed/etc. it should be stored somewhere else.

-- 
Ville Syrjälä
Intel