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Commit e0719165 authored by Viresh Kumar's avatar Viresh Kumar Committed by Vinod Koul
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dmaengine/amba-pl08x: Align lli_len to max(src.width, dst.width)



Currently lli_len is aligned to min of two widths, which looks to be incorrect.
Instead it should be aligned to max of both widths.

Lets say, total_size = 441 bytes

MIN: lets check if min() suits or not:

CASE 1: srcwidth = 1, dstwidth = 4
min(src, dst) = 1

i.e. We program transfer size in control reg to 441.
Now, till 440 bytes everything is fine, but on the last byte DMAC can't transfer
1 byte to dst, as its width is 4.

CASE 2: srcwidth = 4, dstwidth = 1
min(src, dst) = 1

i.e. we program transfer size in control reg to 110 (data transferred = 110 * srcwidth).
So, here too 1 byte is left, but on the source side.

MAX: Lets check if max() suits or not:

CASE 3: srcwidth = 1, dstwidth = 4
max(src, dst) = 4

Aligned size is 440

i.e. We program transfer size in control reg to 440.
Now, all 440 bytes will be transferred without any issues.

CASE 4: srcwidth = 4, dstwidth = 1
max(src, dst) = 4

Aligned size is 440

i.e. We program transfer size in control reg to 110 (data transferred = 110 * srcwidth).
Now, also all 440 bytes will be transferred without any issues.

Signed-off-by: default avatarViresh Kumar <viresh.kumar@st.com>
Acked-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent 03af500f
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+7 −5
Original line number Diff line number Diff line
@@ -669,20 +669,22 @@ static int pl08x_fill_llis_for_desc(struct pl08x_driver_data *pl08x,
		 * width left
		 */
		while (bd.remainder > (mbus->buswidth - 1)) {
			size_t lli_len, tsize;
			size_t lli_len, tsize, width;

			/*
			 * If enough left try to send max possible,
			 * otherwise try to send the remainder
			 */
			lli_len = min(bd.remainder, max_bytes_per_lli);

			/*
			 * Check against minimum bus alignment: Calculate actual
			 * Check against maximum bus alignment: Calculate actual
			 * transfer size in relation to bus width and get a
			 * maximum remainder of the smallest bus width - 1
			 * maximum remainder of the highest bus width - 1
			 */
			tsize = lli_len / min(mbus->buswidth, sbus->buswidth);
			lli_len	= tsize * min(mbus->buswidth, sbus->buswidth);
			width = max(mbus->buswidth, sbus->buswidth);
			lli_len = (lli_len / width) * width;
			tsize = lli_len / bd.srcbus.buswidth;

			dev_vdbg(&pl08x->adev->dev,
				"%s fill lli with single lli chunk of "