From 758535c4e3cdd2b5b09565d9651aaa541aac3de8 Mon Sep 17 00:00:00 2001 From: Arindam Nath Date: Thu, 5 May 2011 12:19:00 +0530 Subject: [PATCH] mmc: sdhci: reset sdclk before setting high speed enable As per Host Controller spec v3.00, we reset SDCLK before setting High Speed Enable, and then set it back to avoid generating clock gliches. Before enabling SDCLK again, we make sure the clock is stable, so we use sdhci_set_clock(). Tested by Zhangfei Gao with a Toshiba uhs card and general hs card, on mmp2 in SDMA mode. Signed-off-by: Arindam Nath Reviewed-by: Philip Rakity Tested-by: Philip Rakity Acked-by: Zhangfei Gao Signed-off-by: Chris Ball --- drivers/mmc/host/sdhci.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 8072e16d6d46..409cde5970ae 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1243,13 +1243,12 @@ static void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) else ctrl &= ~SDHCI_CTRL_HISPD; - sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL); - if (host->version >= SDHCI_SPEC_300) { u16 ctrl_2; ctrl_2 = sdhci_readw(host, SDHCI_HOST_CONTROL2); if (!(ctrl_2 & SDHCI_CTRL_PRESET_VAL_ENABLE)) { + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL); /* * We only need to set Driver Strength if the * preset value enable is not set. @@ -1261,8 +1260,30 @@ static void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios) ctrl_2 |= SDHCI_CTRL_DRV_TYPE_C; sdhci_writew(host, ctrl_2, SDHCI_HOST_CONTROL2); + } else { + /* + * According to SDHC Spec v3.00, if the Preset Value + * Enable in the Host Control 2 register is set, we + * need to reset SD Clock Enable before changing High + * Speed Enable to avoid generating clock gliches. + */ + u16 clk; + unsigned int clock; + + /* Reset SD Clock Enable */ + clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL); + clk &= ~SDHCI_CLOCK_CARD_EN; + sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL); + + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL); + + /* Re-enable SD Clock */ + clock = host->clock; + host->clock = 0; + sdhci_set_clock(host, clock); } - } + } else + sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL); /* * Some (ENE) controllers go apeshit on some ios operation, -- 2.20.1