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authorAndy Walls <awalls@radix.net>2009-11-09 21:55:30 -0500
committerMauro Carvalho Chehab <mchehab@redhat.com>2009-12-05 15:41:52 -0500
commit22dce188ef3e1e058ceabe3b3072640d7568f764 (patch)
tree6a5ee29e5b7cdf9125bea7456c8de75ab0861b92 /drivers/media/video/cx18/cx18-queue.c
parent52fcb3ecc6707f52dfe4297f96b7609d4ba517fb (diff)
V4L/DVB (13430): cx18: Fix YUV capture so that encoder passes a single frame per transfer
Fix YUV capture such that the encoder will pass one frame per transfer. This will allow the application to maintain frame alignment when a transfer from the encoder is missed due to high system latency in service the CX23418 IRQ. Also force YUV buffer sizes to be specified in multiples of 33.75 kB, the smalled amount of buffer sizes need to store a complete set of HM12 4:2:0 macroblocks specifying 32 lines of the frame. A full 60Hz/525 line screen requires 15 * 33.75 kB per frame and a full 50Hz/625 line screen requires 18 * 33.75 kB per frame so the default buffer size is 3 * 33.75 kB, requiring exactly 5 or 6 buffers per MDL respectively. The bytes needed per frame and hence MDL need not be the bytes in an integer number of buffers. However, if frame artifacts are seen with scaled screen sizes, the YUV buffer size can be set 34 kB (33.75 kB) to get rid of the artifacts at the cost of more copies between the kernel and userspace. Signed-off-by: Andy Walls <awalls@radix.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'drivers/media/video/cx18/cx18-queue.c')
-rw-r--r--drivers/media/video/cx18/cx18-queue.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/drivers/media/video/cx18/cx18-queue.c b/drivers/media/video/cx18/cx18-queue.c
index c1a49ecf9d98..98cbf001f8da 100644
--- a/drivers/media/video/cx18/cx18-queue.c
+++ b/drivers/media/video/cx18/cx18-queue.c
@@ -348,9 +348,11 @@ int cx18_stream_alloc(struct cx18_stream *s)
348 if (s->buffers == 0) 348 if (s->buffers == 0)
349 return 0; 349 return 0;
350 350
351 CX18_DEBUG_INFO("Allocate %s stream: %d x %d buffers (%dkB total)\n", 351 CX18_DEBUG_INFO("Allocate %s stream: %d x %d buffers "
352 "(%d.%02d kB total)\n",
352 s->name, s->buffers, s->buf_size, 353 s->name, s->buffers, s->buf_size,
353 s->buffers * s->buf_size / 1024); 354 s->buffers * s->buf_size / 1024,
355 (s->buffers * s->buf_size * 100 / 1024) % 100);
354 356
355 if (((char __iomem *)&cx->scb->cpu_mdl[cx->free_mdl_idx + s->buffers] - 357 if (((char __iomem *)&cx->scb->cpu_mdl[cx->free_mdl_idx + s->buffers] -
356 (char __iomem *)cx->scb) > SCB_RESERVED_SIZE) { 358 (char __iomem *)cx->scb) > SCB_RESERVED_SIZE) {