thank you for your reply.Running FHD 23in LG displays just fine for me on 3-lanes. 2-lanes for FHD is not possible at all!
Will test your timings when time permits (not earlier than Tuesday next week).
For running the bridge on 4-lanes one will require the external ref clock.
yes, running 1920x1080x60hz in 2-lanes is impossible, I get black screen too.
but if I decrease the clock-frequency from 140Mhz(which means 60hz) to 125Mhz, 2-lane works.
just the refresh rate is down to 54hz, not 60hz.
even I set to 1-lane, it still works. the refresh rate is also 54hz.
2-lane and 1-lane do not work at 140M clock-frequency(60hz).
I find when I set clock-frequency to 125Mhz, the adjusted clock-frequency in driver is still 125Mhz.
but when set to 140M(3lane), the adjusted clock will increase to 166Mhz, and fill more blank porch to get 60hz refresh rate.
so commonly I always use 125Mhz , because I guess 125Mhz may be more stable than 140Mhz.
and last, I find that there may be a little error in the linux sn65dsi83.c driver.
that in the sn65dsi83_atomic_pre_enable() function,
Code:
// le16val = cpu_to_le16(mode->hsync_end - mode->hsync_start); le16val = cpu_to_le16((mode->hsync_end - mode->hsync_start)/2); regmap_bulk_write(ctx->regmap, REG_VID_CHA_HSYNC_PULSE_WIDTH_LOW, &le16val, 2); //0x2c le16val = cpu_to_le16(mode->vsync_end - mode->vsync_start); regmap_bulk_write(ctx->regmap, REG_VID_CHA_VSYNC_PULSE_WIDTH_LOW, &le16val, 2); regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_BACK_PORCH,// mode->htotal - mode->hsync_end); //0x34 (mode->htotal - mode->hsync_end)/2); //0x34 regmap_write(ctx->regmap, REG_VID_CHA_VERTICAL_BACK_PORCH, mode->vtotal - mode->vsync_end); regmap_write(ctx->regmap, REG_VID_CHA_HORIZONTAL_FRONT_PORCH,// mode->hsync_start - mode->hdisplay); //0x38 (mode->hsync_start - mode->hdisplay)/2); //0x38REG_VID_CHA_HSYNC_PULSE_WIDTH_LOW,
REG_VID_CHA_HORIZONTAL_BACK_PORCH
REG_VID_CHA_HORIZONTAL_FRONT_PORCH
should be divided by 2 for sn65dsi84 beacause lvds is 2-way, odd and even.
I will test more time, to see if clock at 125Mhz, and horizontal porch divided by 2, will the screen flicker occurs again.
3-lane, 140Mhz, and original driver, the screen will flicker after some random time, as the video I uploaded, that's why I want to use 4-lane...but fail.
Statistics: Posted by dcrane — Mon Apr 28, 2025 2:14 am