Set proper ATA UDMA mode for bf548 according to system clock.

UDMA Mode - Frequency compatibility

UDMA5 - 100 MB/s   - SCLK  = 133 MHz
UDMA4 - 66 MB/s    - SCLK >=  80 MHz
UDMA3 - 44.4 MB/s  - SCLK >=  50 MHz
UDMA2 - 33 MB/s    - SCLK >=  40 MHz

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/ata/pata_bf54x.c b/drivers/ata/pata_bf54x.c
index 81db405a5445..088a41f4e656 100644
--- a/drivers/ata/pata_bf54x.c
+++ b/drivers/ata/pata_bf54x.c
@@ -1489,6 +1489,8 @@ static int __devinit bfin_atapi_probe(struct platform_device *pdev)
         int board_idx = 0;
         struct resource *res;
         struct ata_host *host;
+        unsigned int fsclk = get_sclk();
+        int udma_mode = 5;
         const struct ata_port_info *ppi[] =
                 { &bfin_port_info[board_idx], NULL };
 
@@ -1507,6 +1509,11 @@ static int __devinit bfin_atapi_probe(struct platform_device *pdev)
         if (res == NULL)
                 return -EINVAL;
 
+        while (bfin_port_info[board_idx].udma_mask>0 && udma_fsclk[udma_mode] > fsclk) {
+                udma_mode--;
+                bfin_port_info[board_idx].udma_mask >>= 1;
+        }
+
         /*
          * Now that that's out of the way, wire up the port..
          */