On 11/14/19 2:50 PM, Stefan Agner wrote: > On 2019-11-14 14:17, Marek Vasut wrote: >> The bus_flags and bus_format handling logic does not seem to cover >> all potential usecases. Specifically, this seems to fail with an >> "edt,etm0700g0edh6" display attached to an 24bit display interface, >> with interface-pix-fmt = "rgb24" set in DT. >> >> In this specific setup, the panel-simple.c driver entry for the display >> sets .bus_flags to non-zero value. However, as imxpd->bus_format is set >> from the DT property "interface-pix-fmt", imx_pd_encoder_atomic_check() >> will set imx_crtc_state->bus_flags = imxpd->bus_flags even though the >> imxpd->bus_flags is zero, while the di->bus_flags is correctly set by >> the panel-simple.c and non-zero. The result is incorrect flags being >> used for the display configuration and thus an image corruption. >> (Specifically, DRM_BUS_FLAG_PIXDATA_POSEDGE is not propagated and thus >> the ipuv3 clocks pixels on the wrong edge). >> >> This patch fixes the problem by overriding the imx_crtc_state->bus_format >> from the imxpd->bus_format only if the DT property "interface-pix-fmt" is >> present or if the DI provides no formats. Similarly for bus_flags, which >> are set from imxpd->bus_flags only if the DI provides no formats. > > So this basically prioritizes imxpd->bus_format over what the display > provides? Is this correct in all situations? > > I was thinking that interface-pix-fmt is the legacy way to define the > bus format and it should be provided by the display nowadays. > > However, I guess there is the case where you connect a 18-bit display to > a 24-bit bus (leaving some bits unconnected). Depending on how the > colors/bits are distributed one cannot use 18-bit mode on SoC side but > has to use 24-bit. So the bus format becomes a connection specific > property... I guess the interface-pix-fmt can serve that role. So, can this patch go in ? It's fixing an actual issue for me -- very much what Stefan described above. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
