From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx170.postini.com [74.125.245.170]) by kanga.kvack.org (Postfix) with SMTP id F23E36B002B for ; Sun, 14 Oct 2012 16:34:51 -0400 (EDT) Message-ID: <1350246895.11504.6.camel@gitbox> Subject: Re: dma_alloc_coherent fails in framebuffer From: Tony Prisk Date: Mon, 15 Oct 2012 09:34:55 +1300 In-Reply-To: <1350192523.10946.4.camel@gitbox> References: <1350192523.10946.4.camel@gitbox> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Arnd Bergmann Cc: Rob Herring , Arm Kernel Mailing List , mgorman@suse.de, linux-mm@kvack.org On Sun, 2012-10-14 at 18:28 +1300, Tony Prisk wrote: > Up until 07 Oct, drivers/video/wm8505-fb.c was working fine, but on the > 11 Oct when I did another pull from linus all of a sudden > dma_alloc_coherent is failing to allocate the framebuffer any longer. > > I did a quick look back and found this: > > ARM: add coherent dma ops > > arch_is_coherent is problematic as it is a global symbol. This > doesn't work for multi-platform kernels or platforms which can support > per device coherent DMA. > > This adds arm_coherent_dma_ops to be used for devices which connected > coherently (i.e. to the ACP port on Cortex-A9 or A15). The arm_dma_ops > are modified at boot when arch_is_coherent is true. > > Signed-off-by: Rob Herring > Cc: Russell King > Cc: Marek Szyprowski > Signed-off-by: Marek Szyprowski > > > This is the only patch lately that I could find (not that I would claim > to be any good at finding things) that is related to the problem. Could > it have caused the allocations to fail? > > Regards > Tony P Have done a bit more digging and found the cause - not Rob's patch so apologies. The cause of the regression is this patch: