On Thu, Jul 28, 2022 at 02:18:38PM -0700, Doug Anderson wrote: > Hi, > > On Thu, Jul 28, 2022 at 10:34 AM Abhinav Kumar > <quic_abhinavk@xxxxxxxxxxx> wrote: > > > > Hi Rob and Doug > > > > On 7/22/2022 10:36 AM, Rob Clark wrote: > > > On Fri, Jul 22, 2022 at 9:48 AM Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > > >> > > >> Hi, > > >> > > >> On Fri, Jul 22, 2022 at 9:37 AM Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote: > > >>> > > >>> + sankeerth > > >>> > > >>> Hi Doug > > >>> > > >>> On 7/21/2022 3:23 PM, Douglas Anderson wrote: > > >>>> The Sharp LQ140M1JW46 panel is on the Qualcomm sc7280 CRD reference > > >>>> board. This panel supports 144 Hz and 60 Hz. In the EDID, the 144 Hz > > >>>> mode is listed first and thus is marked preferred. The EDID decode I > > >>>> ran says: > > >>>> > > >>>> First detailed timing includes the native pixel format and preferred > > >>>> refresh rate. > > >>>> > > >>>> ... > > >>>> > > >>>> Detailed Timing Descriptors: > > >>>> DTD 1: 1920x1080 143.981 Hz 16:9 166.587 kHz 346.500 MHz > > >>>> Hfront 48 Hsync 32 Hback 80 Hpol N > > >>>> Vfront 3 Vsync 5 Vback 69 Vpol N > > >>>> DTD 2: 1920x1080 59.990 Hz 16:9 69.409 kHz 144.370 MHz > > >>>> Hfront 48 Hsync 32 Hback 80 Hpol N > > >>>> Vfront 3 Vsync 5 Vback 69 Vpol N > > >>>> > > >>>> I'm proposing here that the above is actually a bug and that the 60 Hz > > >>>> mode really should be considered preferred by Linux. > > > > Its a bit tricky to say that this is a bug but I think we can certainly > > add here that for an internal display we would have ideally had the > > lower resolution first to indicate it as default. > > Yeah, it gets into the vagueness of the EDID spec in general. As far > as I can find it's really up to the monitor to decide by what means it > chooses the "preferred" refresh rate if the monitor can support many. > Some displays may decide that the normal rate is "preferred" and some > may decide that the high refresh rate is "preferred". Neither display > is "wrong" per say, but it's nice to have some consistency here and to > make it so that otherwise "dumb" userspace will get something > reasonable by default. I'll change it to say: > > While the EDID spec appears to allow a display to use any criteria for > picking which refresh mode is "preferred" or "optimal", that vagueness > is a bit annoying. From Linux's point of view let's choose the 60 Hz > one as the default. And if we start making that decision, it should be for all panels with a similar constraint, so most likely handled by the core, and the new policy properly documented. Doing that just for a single panel is weird. Maxime
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