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dmaengine/amba-pl08x: Choose peripheral bus as master bus 

When we have DMA transfers between peripheral and memory, then we shouldn't
reduce width of peripheral at all, as that may be a strict requirement. But we
can always reduce width of memory access, with some compromise in performance.
Thus, we must select peripheral as master and not memory.

Also this rearranges code to make it shorter.

Signed-off-by: Viresh Kumar <viresh.kumar@st.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Viresh Kumar 2011-08-05 15:32:41 +05:30 committed by Vinod Koul
parent e071916580
commit 036f05fd6d
1 changed files with 7 additions and 17 deletions
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24
drivers/dma/amba-pl08x.c
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@ -499,34 +499,24 @@ struct pl08x_lli_build_data {
* byte data), slave is still not aligned, then its width will be reduced to
* BYTE.
* - prefers the destination bus if both available
* - if fixed address on one bus the other will be chosen
* - prefers bus with fixed address (i.e. peripheral)
*/
static void pl08x_choose_master_bus(struct pl08x_lli_build_data *bd,
struct pl08x_bus_data **mbus, struct pl08x_bus_data **sbus, u32 cctl)
{
if (!(cctl & PL080_CONTROL_DST_INCR)) {
*mbus = &bd->srcbus;
*sbus = &bd->dstbus;
} else if (!(cctl & PL080_CONTROL_SRC_INCR)) {
*mbus = &bd->dstbus;
*sbus = &bd->srcbus;
} else if (!(cctl & PL080_CONTROL_SRC_INCR)) {
*mbus = &bd->srcbus;
*sbus = &bd->dstbus;
} else {
if (bd->dstbus.buswidth == 4) {
if (bd->dstbus.buswidth >= bd->srcbus.buswidth) {
*mbus = &bd->dstbus;
*sbus = &bd->srcbus;
} else if (bd->srcbus.buswidth == 4) {
*mbus = &bd->srcbus;
*sbus = &bd->dstbus;
} else if (bd->dstbus.buswidth == 2) {
*mbus = &bd->dstbus;
*sbus = &bd->srcbus;
} else if (bd->srcbus.buswidth == 2) {
*mbus = &bd->srcbus;
*sbus = &bd->dstbus;
} else {
/* bd->srcbus.buswidth == 1 */
*mbus = &bd->dstbus;
*sbus = &bd->srcbus;
*mbus = &bd->srcbus;
*sbus = &bd->dstbus;
}
}
}