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[media] tw68: simplify tw68_buffer_count

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The code to calculate the maximum number of buffers allowed in 4 MB
is 1) wrong if PAGE_SIZE != 4096 and 2) unnecessarily complex.

Fix and simplify the code.

Reported-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
This commit is contained in:
Hans Verkuil 2014-09-04 13:26:52 -03:00 committed by Mauro Carvalho Chehab
parent f1b6a73532
commit 947b38bb11
1 changed files with 1 additions and 10 deletions
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11
drivers/media/pci/tw68/tw68-video.c
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@ -361,22 +361,13 @@ int tw68_video_start_dma(struct tw68_dev *dev, struct tw68_buf *buf)
/* ------------------------------------------------------------------ */
/* nr of (tw68-)pages for the given buffer size */
static int tw68_buffer_pages(int size)
{
size = PAGE_ALIGN(size);
size += PAGE_SIZE; /* for non-page-aligned buffers */
size /= 4096;
return size;
}
/* calc max # of buffers from size (must not exceed the 4MB virtual
* address space per DMA channel) */
static int tw68_buffer_count(unsigned int size, unsigned int count)
{
unsigned int maxcount;
maxcount = 1024 / tw68_buffer_pages(size);
maxcount = (4 * 1024 * 1024) / roundup(size, PAGE_SIZE);
if (count > maxcount)
count = maxcount;
return count;