From mboxrd@z Thu Jan 1 00:00:00 1970 From: arend@broadcom.com (Arend van Spriel) Date: Tue, 9 Dec 2014 12:07:27 +0100 Subject: using DMA-API on ARM In-Reply-To: <20141209102904.GJ11285@n2100.arm.linux.org.uk> References: <5481794E.4050406@broadcom.com> <2863746.4sUSEYqahB@wuerfel> <20141208160316.GM16185@e104818-lin.cambridge.arm.com> <5485D97D.1040404@broadcom.com> <5486CCBC.3@broadcom.com> <20141209102904.GJ11285@n2100.arm.linux.org.uk> Message-ID: <5486D7EF.6010902@broadcom.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 12/09/14 11:29, Russell King - ARM Linux wrote: > On Tue, Dec 09, 2014 at 11:19:40AM +0100, Arend van Spriel wrote: >> The issue did not trigger overnight so it seems setting bit 22> Attribute _Override_ Enable> solves the issue over here. Now the question is >> how to move forward with this. As I understood from Catalin this patch was >> not included as it was not considered responsibility of the linux kernel. > > It is preferable for firmware to configure the L2 cache appropriately, > which includes things like the prefetch offsets as well as feature bits > like bit 22. > > I think what I'll do is queue up a patch which adds a warning if bit 22 > is not set, suggesting that firmware is updated to set this bit. I was thinking in the same direction. Thanks to you all for looking into this. It did not feel right to use the dma_sync_single_for_cpu() for memory allocated with dma_alloc_coherent() and I am glad this got cleared up. Regards, Arend