From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Date: Sat, 26 Jul 2014 15:07:08 +0200 Subject: [U-Boot] [PATCH v3 03/10] sunxi: Remove mmc DMA support In-Reply-To: <20140723203550.14aaa8e6@i7> References: <1402306622-18485-1-git-send-email-hdegoede@redhat.com> <1402306622-18485-4-git-send-email-hdegoede@redhat.com> <20140723203550.14aaa8e6@i7> Message-ID: <53D3A7FC.7090904@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi, On 07/23/2014 07:35 PM, Siarhei Siamashka wrote: > On Mon, 9 Jun 2014 11:36:55 +0200 > Hans de Goede wrote: > >> The DMA code in sunxi_mmc.c is broken. mmc_trans_data_by_dma() allocates the >> dma descriptors on the stack, and then exits while the dma transfer is in >> progress, so the dma engine is reading stack memory which at that point may >> be re-used. So far we've gotten away with this by luck, but recent u-boot >> changes have shifted the stack start address by 16 bytes, which combined >> with dma alignment now exposes this problem. >> >> Since we end up just busy waiting for the dma engine anyway, this commit >> fixes things by simply removing the dma code, resulting in smaller bug-free >> code. >> >> Signed-off-by: Hans de Goede >> Acked-by: Ian Campbell > > Acked-by: Siarhei Siamashka Thanks for the review. Note Ian has already submitted a pull-request for these patches, so your ack won't make it upstream. > Was it a good idea to keep v2014.07 release relying on luck without > this patch? Considering that things just work there, and the timing of when I found this out, yes. Regards, Hans