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: Wed, 19 Dec 2018 16:50:26 +0100 Message-ID: <20181219155026.2mpnmdibs3i6ianh@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="pabpp542fin7m244" 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 --pabpp542fin7m244 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline On Tue, Dec 11, 2018 at 10:30:08PM +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. > > > > So, just like I asked in your v4, twice, > > > > http://lists.infradead.org/pipermail/linux-arm-kernel/2018-November/615339.html > > I don't know how can I comment here. Not quite clearly understand your > setup, because I have verified 3 different panels from different > vendors one with 2-lane, another with 4-lane and one with video format > and another one is burstmode format. I even verified with the clock > rate and register details. > > Please suggest me, what can look further on this. You had a reason to do these patches in the first place, yet you never mention it anywhere in your commit logs. it would address the first part of my comment. And I can help you nail down whatever is going on here, but I would need the panel datasheet for that. It is my second point. Maxime -- Maxime Ripard, Bootlin Embedded Linux and Kernel engineering https://bootlin.com --pabpp542fin7m244--