On Tue, Nov 20, 2018 at 09:55:42PM +0530, Jagan Teki wrote: > On Tue, Nov 20, 2018 at 9:27 PM Maxime Ripard <maxime.rip...@bootlin.com> > wrote: > > > > On Thu, Nov 15, 2018 at 11:19:53PM +0530, Jagan Teki wrote: > > > On Thu, Nov 15, 2018 at 3:26 PM Maxime Ripard <maxime.rip...@bootlin.com> > > > 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 <ja...@amarulasolutions.com> > > > > > > > > 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. > > > > Not even the timings? How did you get that information then? > > datasheet has timing values, but this changes need controller > information about VBP register that I don't have. But again existing > VBP is not back porch for real, it's front porch.
Yet, this breaks the existing setup. So again: > > > > 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". Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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