From 27151dc9e363c0033d7375863c0d284f8c4b636a Mon Sep 17 00:00:00 2001 From: Kishore Kadiyala Date: Tue, 10 Aug 2010 18:01:46 -0700 Subject: [PATCH] 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 Signed-off-by: Venkatraman S Signed-off-by: Nishanth Menon Acked-by: Madhusudhan Chikkature Tested-by: Jarkko Nikula Cc: Adrian Hunter Cc: Matt Fleming Cc: Tony Lindgren Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/mmc/host/omap_hsmmc.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/drivers/mmc/host/omap_hsmmc.c b/drivers/mmc/host/omap_hsmmc.c index b032828c612..a0c8515cb3b 100644 --- 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; -- 2.20.1