mmc: omap: fix for bus width which improves SD card's peformance.

This patch improves low speeds for SD cards.

OMAP-MMC controller's can support maximum bus width of '8'.  when bus
width is mentioned as "8" in controller data,the SD stack will check
whether bus width is "4" and if not it will set bus width to "1" and there
by degrading performance.  This patch fixes the issue and improves the
performance of SD cards.

Signed-off-by: Kishore Kadiyala <[email protected]>
Signed-off-by: Venkatraman S <[email protected]>
Signed-off-by: Nishanth Menon <[email protected]>
Acked-by: Madhusudhan Chikkature <[email protected]>
Tested-by: Jarkko Nikula <[email protected]>
Cc: Adrian Hunter <[email protected]>
Cc: Matt Fleming <[email protected]>
Cc: Tony Lindgren <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c
index b032828c61263028963bd412a7455546d5e86ce7..a0c8515cb3b9809230b0d59b789fa6f77661a5c2 100644 (file)
--- a/drivers/mmc/host/omap_hsmmc.c
+++ b/drivers/mmc/host/omap_hsmmc.c
@@ -2096,10 +2096,23 @@ static int __init omap_hsmmc_probe(struct platform_device *pdev)
        mmc->caps |= MMC_CAP_MMC_HIGHSPEED | MMC_CAP_SD_HIGHSPEED |
                     MMC_CAP_WAIT_WHILE_BUSY;
 
-       if (mmc_slot(host).wires >= 8)
+       switch (mmc_slot(host).wires) {
+       case 8:
                mmc->caps |= MMC_CAP_8_BIT_DATA;
-       else if (mmc_slot(host).wires >= 4)
+               /* Fall through */
+       case 4:
                mmc->caps |= MMC_CAP_4_BIT_DATA;
+               break;
+       case 1:
+               /* Nothing to crib here */
+       case 0:
+               /* Assuming nothing was given by board, Core use's 1-Bit */
+               break;
+       default:
+               /* Completely unexpected.. Core goes with 1-Bit Width */
+               dev_crit(mmc_dev(host->mmc), "Invalid width %d\n used!"
+                       "using 1 instead\n", mmc_slot(host).wires);
+       }
 
        if (mmc_slot(host).nonremovable)
                mmc->caps |= MMC_CAP_NONREMOVABLE;