[v2,1/4] pxa_camera: Enforce YUV422P frame sizes to be 16 multiples
Commit Message
Due to DMA constraints, the DMA chain always transfers bytes
from the QIF fifos to memory in 8 bytes units. In planar
formats, that could mean 0 padding between Y and U plane
(and between U and V plane), which is against YUV422P
standard.
Therefore, a frame size is required to be a multiple of 16
(so U plane size is a multiple of 8). It is enforced in
try_fmt() and set_fmt() primitives, be aligning height then
width on 4 multiples as need be, to reach a 16 multiple.
Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
---
drivers/media/video/pxa_camera.c | 28 +++++++++++++++++++---------
1 files changed, 19 insertions(+), 9 deletions(-)
@@ -162,6 +162,8 @@
CICR0_PERRM | CICR0_QDM | CICR0_CDM | CICR0_SOFM | \
CICR0_EOFM | CICR0_FOM)
+#define PIX_YUV422P_ALIGN 16 /* YUV422P pix size should be a multiple of 16 */
+
/*
* Structures
*/
@@ -241,15 +243,11 @@ static int pxa_videobuf_setup(struct videobuf_queue *vq, unsigned int *count,
dev_dbg(&icd->dev, "count=%d, size=%d\n", *count, *size);
- /* planar capture requires Y, U and V buffers to be page aligned */
- if (pcdev->channels == 3) {
- *size = PAGE_ALIGN(icd->width * icd->height); /* Y pages */
- *size += PAGE_ALIGN(icd->width * icd->height / 2); /* U pages */
- *size += PAGE_ALIGN(icd->width * icd->height / 2); /* V pages */
- } else {
- *size = icd->width * icd->height *
- ((icd->current_fmt->depth + 7) >> 3);
- }
+ if (pcdev->channels == 3)
+ *size = icd->width * icd->height * 2;
+ else
+ *size = roundup(icd->width * icd->height *
+ ((icd->current_fmt->depth + 7) >> 3), 8);
if (0 == *count)
*count = 32;
@@ -1234,6 +1232,18 @@ static int pxa_camera_try_fmt(struct soc_camera_device *icd,
pix->width = 2048;
pix->width &= ~0x01;
+ /*
+ * YUV422P planar format requires images size to be a 16 bytes
+ * multiple. If not, zeros will be inserted between Y and U planes, and
+ * U and V planes, and YUV422P standard would be violated.
+ */
+ if (xlate->host_fmt->fourcc == V4L2_PIX_FMT_YUV422P) {
+ if (!IS_ALIGNED(pix->width * pix->height, PIX_YUV422P_ALIGN))
+ pix->height = ALIGN(pix->height, PIX_YUV422P_ALIGN / 2);
+ if (!IS_ALIGNED(pix->width * pix->height, PIX_YUV422P_ALIGN))
+ pix->width = ALIGN(pix->width, PIX_YUV422P_ALIGN / 2);
+ }
+
pix->bytesperline = pix->width *
DIV_ROUND_UP(xlate->host_fmt->depth, 8);
pix->sizeimage = pix->height * pix->bytesperline;