On Sat, 8 Jul 2023 at 22:39, Marek Vasut <marex@xxxxxxx> wrote: > > On 7/8/23 17:53, Dmitry Baryshkov wrote: > > On 08/07/2023 18:40, Marek Vasut wrote: > >> On 7/7/23 10:47, Neil Armstrong wrote: > >>> On 07/07/2023 09:18, Neil Armstrong wrote: > >>>> Hi, > >>>> > >>>> On 06/07/2023 11:20, Amit Pundir wrote: > >>>>> On Wed, 5 Jul 2023 at 11:09, Dmitry Baryshkov > >>>>> <dmitry.baryshkov@xxxxxxxxxx> wrote: > >>>>>> > >>>>>> [Adding freedreno@ to cc list] > >>>>>> > >>>>>> On Wed, 5 Jul 2023 at 08:31, Jagan Teki > >>>>>> <jagan@xxxxxxxxxxxxxxxxxxxx> wrote: > >>>>>>> > >>>>>>> Hi Amit, > >>>>>>> > >>>>>>> On Wed, Jul 5, 2023 at 10:15 AM Amit Pundir > >>>>>>> <amit.pundir@xxxxxxxxxx> wrote: > >>>>>>>> > >>>>>>>> Hi Marek, > >>>>>>>> > >>>>>>>> On Wed, 5 Jul 2023 at 01:48, Marek Vasut <marex@xxxxxxx> wrote: > >>>>>>>>> > >>>>>>>>> Do not generate the HS front and back porch gaps, the HSA gap and > >>>>>>>>> EOT packet, as these packets are not required. This makes the > >>>>>>>>> bridge > >>>>>>>>> work with Samsung DSIM on i.MX8MM and i.MX8MP. > >>>>>>>> > >>>>>>>> This patch broke display on Dragonboard 845c (SDM845) devboard > >>>>>>>> running > >>>>>>>> AOSP. This is what I see > >>>>>>>> https://people.linaro.org/~amit.pundir/db845c-userdebug/v6.5-broken-display/PXL_20230704_150156326.jpg. > >>>>>>>> Reverting this patch fixes this regression for me. > >>>>>>> > >>>>>>> Might be msm dsi host require proper handling on these updated > >>>>>>> mode_flags? did they? > >>>>>> > >>>>>> The msm DSI host supports those flags. Also, I'd like to point out > >>>>>> that the patch didn't change the rest of the driver code. So even if > >>>>>> drm/msm ignored some of the flags, it should not have caused the > >>>>>> issue. Most likely the issue is on the lt9611 side. I's suspect that > >>>>>> additional programming is required to make it work with these flags. > >>>>> > >>>>> I spent some time today on smoke testing these flags (individually and > >>>>> in limited combination) on DB845c, to narrow down this breakage to one > >>>>> or more flag(s) triggering it. Here are my observations in limited > >>>>> testing done so far. > >>>>> > >>>>> There is no regression with MIPI_DSI_MODE_NO_EOT_PACKET when enabled > >>>>> alone and system boots to UI as usual. > >>>>> > >>>>> MIPI_DSI_MODE_VIDEO_NO_HFP always trigger the broken display as in the > >>>>> screenshot[1] shared earlier as well. > >>>>> > >>>>> Adding either of MIPI_DSI_MODE_VIDEO_NO_HSA and > >>>>> MIPI_DSI_MODE_VIDEO_NO_HBP always result in no display, unless paired > >>>>> with MIPI_DSI_MODE_VIDEO_NO_HFP and in that case we get the broken > >>>>> display as reported. > >>>>> > >>>>> In short other than MIPI_DSI_MODE_NO_EOT_PACKET flag, all other flags > >>>>> added in this commit break the display on DB845c one way or another. > >>>> > >>>> I think the investigation would be to understand why samsung-dsim > >>>> requires > >>>> such flags and/or what are the difference in behavior between MSM > >>>> DSI and samsung DSIM > >>>> for those flags ? > >>>> > >>>> If someone has access to the lt9611 datasheet, so it requires > >>>> HSA/HFP/HBP to be > >>>> skipped ? and does MSM DSI and samsung DSIM skip them in the same way ? > >> > >> I don't have the LT9611 datasheet, no. > > > > I also don't have an lt9611 datasheet, unfortunately. I was using the > > existing third-party drivers as a source. > > > >> > >> The MX8M DSI (samsung-dsim) skips the HSA/HFP/HBP completely (see > >> i.MX8MP RM 13.6.2.7.2 RGB Interface , there is infographics on the > >> following pages). > > > > Do you know, why did you have to disable HPB/HSA/HFP on your platform? > > What was the result otherwise? > > No image on the HDMI monitor at all. This flags change has fixed the > problem for multiple other bridges too btw, not just the LT9611, but > also TI SN65DSI83 and ICN6211. The flags were likely not set in all > those bridge drivers because no DSI host implemented them so far. MSM DSI host have had those implemented for ages, but we never needed them AFAIR. -- With best wishes Dmitry
