Increase pxa reading performance by reading 4 bytes at a
time instead of 4 reads of 1 byte.
As the mci controller FIFO accepts reads on bytes, halfwords
or words, use words whenether possible.
The boost is for a 250KBytes file read and display (bmp):
- before: 6900ms
- after: 6000ms
Signed-off-by: Robert Jarzmik <robert.jarzmik@xxxxxxx>
---
drivers/mci/pxamci.c | 10 ++++++++--
1 files changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/mci/pxamci.c b/drivers/mci/pxamci.c
index a3f8f22..1634a1d 100644
--- a/drivers/mci/pxamci.c
+++ b/drivers/mci/pxamci.c
@@ -74,8 +74,9 @@ static void pxamci_setup_data(struct pxamci_host *host, struct mci_data *data)
static int pxamci_read_data(struct pxamci_host *host, unsigned char *dst,
unsigned len)
{
- int trf_len, ret = 0;
+ int trf_len, trf_len1, trf_len4, ret = 0;
uint64_t start;
+ u32 *dst4;
mci_dbg("dst=%p, len=%u\n", dst, len);
while (!ret && len > 0) {
@@ -85,8 +86,13 @@ static int pxamci_read_data(struct pxamci_host *host, unsigned char *dst,
ret && !is_timeout(start, 10 * MSECOND);)
if (mmc_readl(MMC_I_REG) & RXFIFO_RD_REQ)
ret = 0;
- for (; !ret && trf_len > 0; trf_len--, len--)
+ trf_len1 = trf_len % 4;
+ trf_len4 = trf_len / 4;
+ for (dst4 = (u32 *)dst; !ret && trf_len4 > 0; trf_len4--)
+ *dst4++ = mmc_readl(MMC_RXFIFO);
+ for (dst = (u8 *)dst4; !ret && trf_len1 > 0; trf_len1--)
*dst++ = mmc_readb(MMC_RXFIFO);
+ len -= trf_len;
}
if (!ret)
--
1.7.5.4
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