Hi Tim, On Wednesday 18 March 2015 09:54:58 Tim Nordell wrote: > On 03/18/15 07:39, Laurent Pinchart wrote: > > On Tuesday 17 March 2015 17:57:30 Tim Nordell wrote: > >> On 04/21/14 07:29, Laurent Pinchart wrote: > >>> Replace the custom buffers queue implementation with a videobuf2 queue. > >>> > >>> Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > >> > >> I realize this is late (it's in the kernel now), but I'm noticing that > >> this does not appear to properly support the scatter-gather buffers that > >> were previously supported as far as I recall (and can tell with what was > >> removed with this patch), especially when using USERPTR. You can > >> observe this using "yavta" with the -u parameter. Can you confirm if > >> this works for you? I get the following output from the kernel when > >> attempting to stream a 640x480 UYVY framebuffer: > >> > >> [ 111.381256] contiguous mapping is too small 589824/614400 > > > > The OMAP3 ISP uses an IOMMU, physically non-contiguous buffers should thus > > be mapped contiguously into the device memory space. I haven't tried > > USERPTR support recently, but this surprises me. It requires > > investigation. Could you give it a try ? > > That's why I wrote the e-mail since I did give it a try. It doesn't > work in kernel v3.19 as expected. I'm using a BT.656 device (and with > the patches I submitted last week since it didn't work for my device > without those that I wrote), so it's a little harder to go back to the > exact patch that causes it to fail (since I believe it's this patch > which is pre-BT.656 support) but I would guess that it's the one I > replied to here. > > The videobuf2-dma-contig framework is what is emitting this error, and > part of it's framework checks that the buffer is fully contiguous in > memory rather than doing scatter-gather. The names might be a bit misleading, vb2-dma-contig requires contiguous memory in the device memory space, not in physical memory. The IOMMU, managed through dma_map_sg_attrs, should have mapped the userptr buffer contiguously in the ISP DMA address space. If it hasn't, that's what need to be investigated. > The function "vb2_dc_get_contiguous_size(...)" is what finds the full > contiguous area of the buffer and reports back internally how much is > available in a row. Would videobuf2-dma-sg have been a better choice here? > I tried a naive conversion to that (that is, I'm sure I messed something > up), but it yielded the kernel spewing messages about "Address Hole seen by > CAM" from the omap_l3_smx driver. vb2-dma-sg is used for devices that support scatter-gather. The OMAP3 ISP doesn't, it requires DMA contiguous memory. -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
