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Interfacing (DSI, CSI, I2C, etc.) • DSI display content wraps

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I have a 800x1280 4-lane ili9881c based DSI display. On the left side (vertical oriented) I have 2 pixels which should be on the right side.

This are the parameters from the manufacturer:

Code:

#VFP 16#VBP 24#VSA 8#HFP 80#HBP 80#HSA 20#frame rate = 60Hz#PCLK = 78.086MHz#MIPI_CLK = 468Mbps (MIPI channel speed)#dsi.PLL_CLOCK = 234Mbps (MTK platform speed)
I have dialed-in the clock like this into the drm_display_mode struct:

Code:

+.clock          = 78086,+.hdisplay       = 800,+.hsync_start    = 800 + 80,+.hsync_end      = 800 + 80 + 20,+.htotal         = 800 + 80 + 20 + 80,+.vdisplay       = 1280,+.vsync_start    = 1280 + 16,+.vsync_end      = 1280 + 16 + 8,+.vtotal         = 1280 + 16 + 8 + 24,
On CM5, this works well.
But on CM4 there is the mentioned 2-Pixel shift/wrap to the left of the display.
If I understand the post viewtopic.php?p=2115052#p2115052 correctly, plld_dsi1 should correlate with the mipi channel speed.

This is what it reports on clk_summary:

Code:

# cat /sys/kernel/debug/clk/clk_summary | grep dsi       plld_dsi1                     3       3        0        500000016   0          0     50000      Y         fe700000.dsi                    phy                                dsi1_ddr                   0       0        0        250000008   0          0     50000      Y            deviceless                      no_connection_id                   dsi1_ddr2                  0       0        0        125000004   0          0     50000      Y            deviceless                      no_connection_id                   dsi1_byte                  1       1        0        62500002    0          0     50000      Y            deviceless                      no_connection_id                      dsi1p                   1       1        0        62500002    0          0     50000      Y               fe700000.dsi                    pixel                           plld_dsi0                     1       1        0        11718751    0          0     50000      Y         deviceless                      no_connection_id                   dsi1e                      1       1        0        100000003   0          0     50000      Y            fe700000.dsi                    escape                          plla_dsi0                     1       1        0        11718750    0          0     50000      Y         deviceless                      no_connection_id          dsi0p                               0       0        0        0           0          0     50000      Y   deviceless                      no_connection_id          dsi0e                               0       0        0        0           0          0     50000      Y   deviceless                      no_connection_id        
Any idea how to fix this?
pixel_shift.jpg

Statistics: Posted by batwing — Thu Jun 19, 2025 3:53 pm — Replies 3 — Views 76



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