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authorViresh Kumar <viresh.kumar@st.com>2011-08-05 14:02:41 +0400
committerVinod Koul <vinod.koul@intel.com>2011-08-25 18:03:39 +0400
commit036f05fd6dcdb6a6b9e55703cb663112fa4c4e42 (patch)
tree073bb36d9d6da0b8687e14f8690a7c0e9a2bcdff /drivers/dma
parente0719165801fad04073e7dcd90e4afd02aba3fb7 (diff)
downloadlinux-036f05fd6dcdb6a6b9e55703cb663112fa4c4e42.tar.xz
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>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/amba-pl08x.c22
1 files changed, 6 insertions, 16 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 4bcf6036f35d..f70aa574c58f 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -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) {
- *mbus = &bd->dstbus;
- *sbus = &bd->srcbus;
- } else if (bd->srcbus.buswidth == 4) {
- *mbus = &bd->srcbus;
- *sbus = &bd->dstbus;
- } else if (bd->dstbus.buswidth == 2) {
+ if (bd->dstbus.buswidth >= bd->srcbus.buswidth) {
*mbus = &bd->dstbus;
*sbus = &bd->srcbus;
- } else if (bd->srcbus.buswidth == 2) {
+ } else {
*mbus = &bd->srcbus;
*sbus = &bd->dstbus;
- } else {
- /* bd->srcbus.buswidth == 1 */
- *mbus = &bd->dstbus;
- *sbus = &bd->srcbus;
}
}
}