From mboxrd@z Thu Jan 1 00:00:00 1970 From: Maxime Ripard Subject: Re: [PATCH v5 07/17] drm/sun4i: sun6i_mipi_dsi: Refactor vertical video start delay Date: Mon, 7 Jan 2019 15:11:58 +0100 Message-ID: <20190107141158.zaimizk4rlqa6xli@flea> References: <20181210161729.29720-1-jagan@amarulasolutions.com> <20181210161729.29720-8-jagan@amarulasolutions.com> <20181211164900.wfmkmbrbj3nmlb3h@flea> Reply-To: maxime.ripard-LDxbnhwyfcJBDgjK7y7TUQ@public.gmane.org Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="2f4sgk2x6n64h3fz" Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Jagan Teki Cc: Chen-Yu Tsai , Michael Turquette , Stephen Boyd , linux-arm-kernel , linux-clk , linux-kernel , dri-devel , Michael Trimarchi , linux-sunxi , linux-amarula-dyjBcgdgk7Pe9wHmmfpqLFaTQe2KTcn/@public.gmane.org List-Id: dri-devel@lists.freedesktop.org --2f4sgk2x6n64h3fz Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline On Fri, Dec 21, 2018 at 02:26:11AM +0530, Jagan Teki wrote: > On Tue, Dec 11, 2018 at 10:19 PM Maxime Ripard > 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 > > > > 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 --2f4sgk2x6n64h3fz--