Den 02.04.2022 18.39, skrev Marek Vasut: > On 4/2/22 09:45, Noralf Trønnes wrote: >> >> >> Den 02.04.2022 06.28, skrev Marek Vasut: >>> On 4/2/22 05:19, Laurent Pinchart wrote: >>>> On Fri, Apr 01, 2022 at 10:36:24PM +0200, Marek Vasut wrote: >>>>> On 4/1/22 20:46, Laurent Pinchart wrote: >>>>>> On Fri, Apr 01, 2022 at 06:37:54PM +0200, Marek Vasut wrote: >>>>>>> Make the width-mm/height-mm panel properties mandatory in >>>>>>> of_get_drm_panel_display_mode(), print error message and >>>>>>> return -ve in case these DT properties are not present. >>>>>>> This is needed to correctly report panel dimensions. >>>>>> >>>>>> Can we guarantee this won't cause a regression ? >>>>> >>>>> For the upstream DTs, I think we can. >>>>> For downstream DTs, we cannot know. >>>> >>>> Are there users of this function whose DT bindings don't require the >>>> width-mm and height-mm properties ? >>> >>> There is literally one user of this function upstream: >>> drivers/gpu/drm/tiny/panel-mipi-dbi.c >> >> Yes, the function was added for that driver since it was so generic in >> nature. What about adding an argument to of_get_drm_panel_display_mode() >> that tells if the properties are mandatory or not? > > Sure, we can do that, but maybe the question here is even bigger than > this series. > > Should every panel set mandatory width_mm/height_mm so e.g. the user > space can infer DPI from it and set up scaling accordingly, or should > width_mm/height_mm be optional ? > > I think width_mm/height_mm should be mandatory for all panels. > > Thoughts ? If this had come up during the review of the driver I would have no problem making it mandatory. It makes sense for DPI. Maybe it's possible to get around the ABI break by getting in a change through -fixes before 5.18 is released? I'm fine with that. Noralf.
