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Commit 947b38bb authored by Hans Verkuil's avatar Hans Verkuil Committed by Mauro Carvalho Chehab
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[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: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
Signed-off-by: default avatarHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent f1b6a735

drivers/media/pci/tw68/tw68-video.c

+1 −10
Original line number Diff line number Diff line
@@ -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;