On Thu, Nov 15, 2018 at 3:26 PM Maxime Ripard <maxime.ripard@xxxxxxxxxxx> wrote: > > Hi, > > On Tue, Nov 13, 2018 at 04:46:15PM +0530, Jagan Teki wrote: > > The horizontal and vertical back porch calculation in BSP > > code is simply following the Linux drm comment diagram, in > > include/drm/drm_modes.h which is > > > > [hv]back porch = [hv]total - [hv]sync_end > > > > BSP code form BPI-M64-bsp is calculating vertical back porch as > > (from linux-sunxi/drivers/video/sunxi/disp2/disp/de/disp_lcd.c) > > > > timmings->ver_sync_time= panel_info->lcd_vspw; > > timmings->ver_back_porch= panel_info->lcd_vbp-panel_info->lcd_vspw; > > > > vbp = panel->lcd_vbp; > > vspw = panel->lcd_vspw; > > dsi_dev[sel]->dsi_basic_size0.bits.vbp = vbp-vspw; > > dsi_dev[sel]->dsi_basic_size0.bits.vbp = panel->lcd_vbp - panel->lcd_vspw; > > => timmings->ver_back_porch + panel_info->lcd_vspw - panel_info->lcd_vspw > > => timmings->ver_back_porch > > => mode->vtotal - mode->end > > > > Which evatually same as mode->vtotal - mode->vsync_end so update the > > same in SUN6I_DSI_BASIC_SIZE0_VBP > > > > On the information note, existing SUN6I_DSI_BASIC_SIZE0_VSA is proper > > value. > > > > Signed-off-by: Jagan Teki <jagan@xxxxxxxxxxxxxxxxxxxx> > > I've tested your changes on my A33 board, and this commit will break > it. > > It creates vblank timeouts, and visual artifacts at the bottom of the > display. Strange, VBP is earlier gives front porch which is anyway wrong. > > Later commits seem to fix the issue, but will create some blanking on > the upper third of the display. > > Since the documentation is quite sparse, and a MIPI-DSI analyzer is > way too expensive, I'd really like to have at least what each of these > commits are actually fixing, and what symptoms each of these were > causing, and not just "the BSP does it". W/o this 2-lane panel is breaking, same vblank timeout and visual artifacts at the bottom of the panel. though the commits may reference BSP, I have at-least tested on 3 different panels for us to prove its working. > > Having some datasheet for the panels you had working would help too. Unfortunately datasheet doesn't have any required information what we actually looking for.
