From: Kishore Kadiyala <[email protected]> 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]> --- drivers/mmc/host/omap_hsmmc.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff -puN drivers/mmc/host/omap_hsmmc.c~mmc-omap-fix-for-bus-width-which-improves-sd-cards-peformance drivers/mmc/host/omap_hsmmc.c --- a/drivers/mmc/host/omap_hsmmc.c~mmc-omap-fix-for-bus-width-which-improves-sd-cards-peformance +++ a/drivers/mmc/host/omap_hsmmc.c @@ -2096,10 +2096,23 @@ static int __init omap_hsmmc_probe(struc 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; _ -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
