From: tomi.valkeinen@ti.com (Tomi Valkeinen) Date: Thu, 9 Jan 2014 10:27:27 +0200 Subject: [PATCH 1/2] ARM: omapfb: add coherent dma memory support In-Reply-To: <79CD15C6BA57404B839C016229A409A83EDB141E@DBDE04.ent.ti.com> References: <1388409550-10720-1-git-send-email-tomi.valkeinen@ti.com> <1388409550-10720-2-git-send-email-tomi.valkeinen@ti.com> <20140107235951.GH5074@atomide.com> <52CD5D13.9090806@ti.com> <79CD15C6BA57404B839C016229A409A83EDB11F5@DBDE04.ent.ti.com> <52CE5123.9050702@gmail.com> <79CD15C6BA57404B839C016229A409A83EDB141E@DBDE04.ent.ti.com> Message-ID: <52CE5D6F.3050700@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 2014-01-09 10:08, Hiremath, Vaibhav wrote: > No, that's what is causing issue to me. Can you try predefined address flow? > Just to highlight, I get UNDERFLOW during boot itself, immediately when it gets mapped to userspace. > > Boot LOG: > > [ 4.822549] Freeing unused kernel memory: 440K (c0919000 - c0987000) > [ 5.276615] OMAPFB: pan_display(0) > [ 5.276625] OMAPFB: setcmap > [ 5.276635] OMAPFB: setcmap > [ 5.293518] OMAPFB: user mmap region start a0000000, len 1536000, off 0 > [ 5.300171] omapdss APPLY error: FIFO UNDERFLOW on gfx, disabling the overlay Hmm that's interesting... So you have some tool that's ran early, which draws something on the screen? Or maybe that's X starting? Ah... I think I understand now. As I mentioned, AM4x has issues already. I think the CPU/others can block DSS when accessing memory. So, if we have bad caching for the mapped framebuffer, the CPU will use more bandwidth when reading/writing to it, and that will cause DSS to underflow. Tomi -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 901 bytes Desc: OpenPGP digital signature URL: