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 ?
Neil
Regards,
Amit Pundir
[1] https://people.linaro.org/~amit.pundir/db845c-userdebug/v6.5-broken-display/PXL_20230704_150156326.jpg
--
With best wishes
Dmitry
