On Fri, Dec 21, 2018 at 02:26:11AM +0530, Jagan Teki wrote: > On Tue, Dec 11, 2018 at 10:19 PM Maxime Ripard > <maxime.ripard@xxxxxxxxxxx> wrote: > > > > On Mon, Dec 10, 2018 at 09:47:19PM +0530, Jagan Teki wrote: > > > Video start delay can be computed by subtracting total vertical > > > timing with front porch timing and with adding 1 delay line for TCON. > > > > > > BSP code form BPI-M64-bsp is computing video start delay as > > > (from linux-sunxi/ > > > drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c) > > > > > > u32 vfp = panel->lcd_vt - panel->lcd_y - panel->lcd_vbp; > > > => (panel->lcd_vt) - panel->lcd_y - (panel->lcd_vbp) > > > => (timmings->ver_front_porch + panel->lcd_vbp + panel->lcd_y) > > > - panel->lcd_y - (panel->lcd_vbp) > > > => timmings->ver_front_porch + panel->lcd_vbp + panel->lcd_y > > > - panel->lcd_y - panel->lcd_vbp > > > => timmings->ver_front_porch > > > > > > So, update the start delay computation accordingly. > > > > > > Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx> > > > > Even though it's a bit better now on my A33 board and I don't have the > > white stripes on the bottom of the display, there's still some > > flickering with your patches applied. > > > > Bisecting it seems to point at that patch, but reverting it doesn't > > make the issue go away, so it's not really clear which one exactly is > > at fault. > > Is reverting this patch, work fine or not? As I was saying, it doesn't. > This patch is trying to make use of front porch instead of existing > back porch to compute the delay. Since we revert the VBP fix patch[1] > to assume VBP as VFP value look like your setup would also require to > revert this change. But as per BSP or drm_mode details all of my > displays even work with and w/o reverting these two. Again, I cannot help you without the datasheet for the panels you're trying to submit. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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