On 2023-05-30 01:39:10, Dmitry Baryshkov wrote: > On 30/05/2023 01:37, Marijn Suijten wrote: > > On 2023-05-30 01:18:40, Dmitry Baryshkov wrote: > > <snip> > >>>>>>> + ret = mipi_dsi_dcs_set_display_on(dsi); > >>>>>>> + if (ret < 0) { > >>>>>>> + dev_err(dev, "Failed to turn display on: %d\n", ret); > >>>>>>> + return ret; > >>>>>>> + } > >>>>>> > >>>>>> My usual question: should the mipi_dsi_dcs_exit_sleep_mode() / mipi_dsi_dcs_set_display_on() be moved from prepare() to enable() part? > >>>>> > >>>>> > >>>>> No, prepare is called before the video stream is started and when display is still in LPM mode and the mode hasn't been set. > >>>>> > >>>> > >>>> Yes, that's my point. Shouldn't we enable the panel _after_ starting the stream? > >>> > >>> I have never investigated what it takes to split these functions, but > >>> some of these panels do show some corruption at startup which may be > >>> circumvented by powering the panel on after starting the video stream? > >>> > >>> I'm just not sure where to make the split: downstream does describe a > >>> qcom,mdss-dsi-on-command and qcom,mdss-dsi-post-panel-on-command, where > >>> the latter only contains set_display_on() (not exit_sleep_mode()). > >>> It is documented like: > >>> > >>> same as "qcom,mdss-dsi-on-command" except commands are sent after > >>> displaying an image." > >>> > >>> So this seems like the right way to split them up, I'll test this out on > >>> all submitted panel drivers. > >> > >> Interesting enough, Neil suggested that sending all the commands during > >> pre_enable() is the correct sequence (especially for VIDEO mode panels), > >> since not all DSI hosts can send commands after switching to the VIDEO mode. > > > > Note that all these panels and Driver-ICs are command-mode, and/or > > programmed to run in command-mode, so there shouldn't be any notion of a > > VIDEO stream (any command-mode frame is just an "arbitrary command" as > > far as I understood). > > Yes, from the data stream point of view. I was talking about the DSI > host being able to send arbitrary commands or not after enabling the > video/cmd stream. Is this a known limitation of SM8250 then? Or is the brightness_set issue more likely a "problem" with the panel that the downstream kernel is "somehow" working around or aware of, and I just haven't found how/where it deals with that? (Alternatively we could be "doing it wrong" for other panels but it turns out to be working anyway) - Marijn