From af951761d01c89eea8f1dcccf8010218e4b55817 Mon Sep 17 00:00:00 2001 From: "ludovic.desroches@atmel.com" Date: Thu, 17 Sep 2015 10:16:19 +0200 Subject: [PATCH] mmc: sdhci: add quirk SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST The Atmel sdhci device needs a new quirk. sdhci_set_clock set the Clock Control Register to 0 before computing the new value and writing it. It disables the internal clock which causes a reset mecanism. If we write the new value before this reset mecanism is done, it will prevent the stabilisation of the internal clock, so a delay is needed. This delay is about 2-3 cycles of the base clock. To be safe, a 1 ms delay is used. Signed-off-by: Ludovic Desroches Signed-off-by: Ulf Hansson --- drivers/mmc/host/sdhci.c | 2 ++ drivers/mmc/host/sdhci.h | 5 +++++ 2 files changed, 7 insertions(+) diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c index 64b7fdbd1a9c..fbc7efdddcb5 100644 --- a/drivers/mmc/host/sdhci.c +++ b/drivers/mmc/host/sdhci.c @@ -1160,6 +1160,8 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock) host->mmc->actual_clock = 0; sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL); + if (host->quirks2 & SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST) + mdelay(1); if (clock == 0) return; diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h index 7c02ff46c8ac..9d4aa31b683a 100644 --- a/drivers/mmc/host/sdhci.h +++ b/drivers/mmc/host/sdhci.h @@ -412,6 +412,11 @@ struct sdhci_host { #define SDHCI_QUIRK2_ACMD23_BROKEN (1<<14) /* Broken Clock divider zero in controller */ #define SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN (1<<15) +/* + * When internal clock is disabled, a delay is needed before modifying the + * SD clock frequency or enabling back the internal clock. + */ +#define SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST (1<<16) int irq; /* Device IRQ */ void __iomem *ioaddr; /* Mapped address */ -- 2.20.1