On Thu, Mar 28, 2019 at 05:23:39PM +0530, Jagan Teki wrote: > On Tue, Mar 19, 2019 at 4:26 PM Maxime Ripard wrote: > > > > On Mon, Mar 11, 2019 at 08:28:22PM +0530, Jagan Teki wrote: > > > On Mon, Mar 11, 2019 at 7:39 PM Maxime Ripard wrote: > > > > > > > > On Thu, Mar 07, 2019 at 09:24:02PM +0530, Jagan Teki wrote: > > > > > On Thu, Mar 7, 2019 at 9:09 PM Maxime Ripard wrote: > > > > > > > > > > > > On Thu, Mar 07, 2019 at 05:49:07PM +0530, Jagan Teki wrote: > > > > > > > On Mon, Mar 4, 2019 at 9:13 PM Maxime Ripard wrote: > > > > > > > > > > > > > > > > On Sun, Mar 03, 2019 at 11:05:24PM +0530, Jagan Teki wrote: > > > > > > > > > TCON DRQ for non-burst DSI mode can computed based on horizontal > > > > > > > > > front porch value, but the current driver trying to include sync > > > > > > > > > timings along with front porch resulting wrong drq. > > > > > > > > > > > > > > > > > > This patch is trying to update the drq by subtracting hsync_start > > > > > > > > > with hdisplay, which is horizontal front porch. > > > > > > > > > > > > > > > > > > Current code: > > > > > > > > > ------------ > > > > > > > > > mode->hsync_end - mode->hdisplay => horizontal front porch + sync > > > > > > > > > > > > > > > > > > With this patch: > > > > > > > > > ---------------- > > > > > > > > > mode->hsync_start - mode->hdisplay => horizontal front porch > > > > > > > > > > > > > > > > > > BSP code form BPI-M64-bsp is computing TCON DRQ set bits > > > > > > > > > for non-burts as (from linux-sunxi/ > > > > > > > > > drivers/video/sunxi/disp2/disp/de/lowlevel_sun50iw1/de_dsi.c) > > > > > > > > > > > > > > > > > > => panel->lcd_ht - panel->lcd_x - panel->lcd_hbp > > > > > > > > > => (timmings->hor_front_porch + panel->lcd_hbp + panel->lcd_x) > > > > > > > > ^ + sync length + > > > > > > > > > - panel->lcd_x - panel->hbp > > > > > > > > > => timmings->hor_front_porch > > > > > > > > ^ + sync > > > > > > > > > => mode->hsync_start - mode->hdisplay > > > > > > > > > > > > > > > > s/hsync_start/hsync_end/ > > > > > > > > > > > > > > No, it should be front porch so it is hsync_start. This change is > > > > > > > trying to update DRQ set to use front porch and above evaluation from > > > > > > > BSP, result the same front front porch > > > > > > > > > > > > > > Current driver has hsync_end - hdisplay which is not front porch > > > > > > > timing (it is adding extra sync timing). > > > > > > > > > > > > It would be if you considered that the back porch actually was the > > > > > > back porch plus the sync length. I have found no such evidence, quite > > > > > > the opposite actually, everything seems to point at the fact that > > > > > > unlike the TCON, the DSI block uses the back porch as only the back > > > > > > porch. > > > > > > > > > > Sorry, I'm not clear about back porch here. > > > > > > > > > > The current code has mode->hsync_end - mode->hdisplay which is Front > > > > > porch + sync time do you think it's not? > > > > > > > > It is. > > > > > > > > > DRQ set time is pure front porch value (according BSP) as I didn't > > > > > see any information about DRQ set bits in manual or anywhere. > > > > > > > > This is what I'm telling you. If you consider the back porch as only > > > > the back porch, then the result of that BSP calculation you mentionned > > > > earlier is the front porch and the sync length. > > > > > > > > You imply that the back porch should actually be treated as the back > > > > porch and the sync length in your calculation. What makes you say so? > > > > > > I'm consider the computations accordingly to drm_modes.h and which > > > matches similar like BSP code. > > > > > > mode->hsync_end - mode->hdisplay = front porch + sync > > > > > > but the actual computation is > > > mode->hsync_start - mode->hdisplay => front porch > > > > > > Which is similar to what BSP is using. > > > > > > => panel->lcd_ht - panel->lcd_x - panel->lcd_hbp > > > => (timmings->hor_front_porch + panel->lcd_hbp + panel->lcd_x) > > > - panel->lcd_x - panel->hbp > > > => timmings->hor_front_porch > > > => mode->hsync_start - mode->hdisplay > > > > You're missing the point. What I'm asking for is why you think that > > panel->lcd_ht == (timmings->hor_front_porch + panel->lcd_hbp + > > panel->lcd_x) and not timmings->hor_front_porch + panel->lcd_hbp + > > sync_width + panel->lcd_x > > No ie not true we can't include sync_width, please see here [1] > > timmings->hor_front_porch= panel_info->lcd_ht-panel_info->lcd_hbp - > panel_info->lcd_x; > panel_info->lcd_ht = timmings->hor_front_porch + panel_info->lcd_hbp + > panel_info->lcd_x; > > and the result of this lcd_ht is exactly matched with Mainline timings > or any supported panel in A64. > > [1] https://github.com/longsleep/linux-pine64/blob/pine64-hacks-1.2/drivers/video/sunxi/disp2/disp/de/disp_lcd.c#L1839 Can we please start to reason in actual timings instead of whatever Allwinner comes up with in their BSP? Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com