[media] tw68: simplify tw68_buffer_count
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>
diff --git a/drivers/media/pci/tw68/tw68-video.c b/drivers/media/pci/tw68/tw68-video.c
index 66fae23..498ead9 100644
--- a/drivers/media/pci/tw68/tw68-video.c
+++ b/drivers/media/pci/tw68/tw68-video.c
@@ -361,22 +361,13 @@
/* ------------------------------------------------------------------ */
-/* 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;