From mboxrd@z Thu Jan 1 00:00:00 1970 From: marex@denx.de (Marek Vasut) Date: Sat, 16 Mar 2013 21:55:27 +0100 Subject: Shifted framebuffer after X11 starts on mx28 In-Reply-To: References: Message-ID: <201303162155.28230.marex@denx.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Dear Fabio Estevam, > Hi, > > I am running 3.8.2 kernel on a mx28evk and when I start X11 I get a > "shifted" framebuffer. > > The framebuffer works well if X11 is not called. > > There is no issue with X11 when running with Freescale 2.6.35 kernel. > > Looking at drivers/video/mxsfb.c there is the following comment: > > /* > * It seems, you can't re-program the controller if it is still running. > * This may lead into shifted pictures (FIFO issue?). > * So, first stop the controller and drain its FIFOs > */ > > So, it looks like that I am still facing this issue when X11 starts. > > If anyone has any suggestions, please let me know. This is not it, I almost hunted the bug down. Hang on. Basically check mxsfb_set_par() and observe fb_info->var.sync . It's set to "something" during regular framebuffer operation and it's set to "something else" during Xorg operation. And that's what causes it to get broken. I forced fb_info->var.sync to the "something" value by hardcoding it in kernel just now for a quick test and X works for me. Best regards, Marek Vasut