On Mon, 28 Aug 2023 18:07:08 -0500, Adam Ford wrote: > On Mon, Aug 28, 2023 at 11:13 AM Adam Ford <aford173@xxxxxxxxx> wrote: > > > > On Mon, Aug 28, 2023 at 10:59 AM Michael Tretter > > <m.tretter@xxxxxxxxxxxxxx> wrote: > > > > > > I tested the i.MX8M Nano EVK with the NXP supplied MIPI-DSI adapter, > > > which uses an ADV7535 MIPI-DSI to HDMI converter. I found that a few > > > modes were working, but in many modes my monitor stayed dark. > > > > > > This series fixes the Samsung DSIM bridge driver to bring up a few more > > > modes: > > > > > > The driver read the rate of the PLL ref clock only during probe. > > > However, if the clock is re-parented to the VIDEO_PLL, changes to the > > > pixel clock have an effect on the PLL ref clock. Therefore, the driver > > > must read and potentially update the PLL ref clock on every modeset. > > > > > > I also found that the rounding mode of the porches and active area has > > > an effect on the working modes. If the driver rounds up instead of > > > rounding down and be calculates them in Hz instead of kHz, more modes > > > start to work. > > > > > > The following table shows the modes that were working in my test without > > > this patch set and the modes that are working now: > > > > > > | Mode | Before | Now | > > > | 1920x1080-60.00 | X | X | > > > | 1920x1080-59.94 | | X | > > > | 1920x1080-50.00 | | X | > > > | 1920x1080-30.00 | | X | > > > | 1920x1080-29.97 | | X | > > > | 1920x1080-25.00 | | X | > > > | 1920x1080-24.00 | | | > > > | 1920x1080-23.98 | | | > > > | 1680x1050-59.88 | | X | > > > | 1280x1024-75.03 | X | X | > > > | 1280x1024-60.02 | X | X | > > > | 1200x960-59.99 | | X | > > > | 1152x864-75.00 | X | X | > > > | 1280x720-60.00 | | | > > > | 1280x720-59.94 | | | > > > | 1280x720-50.00 | | X | > > > | 1024x768-75.03 | | X | > > > | 1024x768-60.00 | | X | > > > | 800x600-75.00 | X | X | > > > | 800x600-60.32 | X | X | > > > | 720x576-50.00 | X | X | > > > | 720x480-60.00 | | | > > > | 720x480-59.94 | X | | > > > | 640x480-75.00 | X | X | > > > | 640x480-60.00 | | X | > > > | 640x480-59.94 | | X | > > > | 720x400-70.08 | | | > > > > > > > Nice! > > > > > Interestingly, the 720x480-59.94 mode stopped working. However, I am > > > able to bring up the 720x480 modes by manually hacking the active area > > > (hsa) to 40 and carefully adjusting the clocks, but something still > > > seems to be off. > > > > Checkout my > > > > branch: https://github.com/aford173/linux/commit/183cf6d154afeb9b0300500b09d7b8ec53047a12 Thanks for the pointer. > > > > I found that certain resolutions don't properly round, and it seemed > > to be related to the size of HFP. HFP of 110 when divded between 4 > > lanes, required a round-up, but then I had to recalculate the rest of > > the horizontal timings to compensate. > > > > I was going to push that as an RFC, but I will investigate your patch > > series first. With my small rounding correction, I am able to get > > 720x480 and 720p on my imx8mp, but not my mini/nano, so I am hoping > > your patch series fixes that issue for me. > > > > > > > > Unfortunately, a few more modes are still not working at all. The NXP > > > downstream kernel has some quirks to handle some of the modes especially > > > wrt. to the porches, but I cannot figure out, what the driver should > > > actually do in these cases. Maybe there is still an error in the > > > calculation of the porches and someone at NXP can chime in. > > > > Hopefully the comment in my above patch explains how the calculation > > is corrected and adjusted to get some of the missing resolutions. > > I tested my above patch and it works to sync 720p-60 on my imx8mp, but > it doesn't seem to sync on my imx8mm using the same monitor and HDMI > cable. I don't have a DSI analyzer, so I might still send out a > modified version of my patch as an RFC once this gets approved. I tested your patch with all modes of my monitor. 720p-60 doesn't work on my imx8mn either. The results are the same for DIV_ROUND_CLOSEST and DIV64_U64_ROUND_UP, but I didn't check for differences in the actually calculated HFP, yet. Michael > > adam > > > > > Michael > > > > > > Signed-off-by: Michael Tretter <m.tretter@xxxxxxxxxxxxxx> > > > > I'll try to reivew this week and respond with my feedback. > > > > adam > > > > > --- > > > Marco Felsch (1): > > > drm/bridge: samsung-dsim: add more mipi-dsi device debug information > > > > > > Michael Tretter (4): > > > drm/bridge: samsung-dsim: reread ref clock before configuring PLL > > > drm/bridge: samsung-dsim: update PLL reference clock > > > drm/bridge: samsung-dsim: adjust porches by rounding up > > > drm/bridge: samsung-dsim: calculate porches in Hz > > > > > > drivers/gpu/drm/bridge/samsung-dsim.c | 42 +++++++++++++++++++++++++---------- > > > include/drm/bridge/samsung-dsim.h | 1 + > > > 2 files changed, 31 insertions(+), 12 deletions(-) > > > --- > > > base-commit: 2dde18cd1d8fac735875f2e4987f11817cc0bc2c > > > change-id: 20230818-samsung-dsim-42346444bce5 > > > > > > Best regards, > > > -- > > > Michael Tretter <m.tretter@xxxxxxxxxxxxxx> > > > >
