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mmc: sdhci: add quirk SDHCI_QUIRK2_NEED_DELAY_AFTER_INT_CLK_RST

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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 <ludovic.desroches@atmel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
This commit is contained in:
ludovic.desroches@atmel.com 2015-09-17 10:16:19 +02:00 committed by Ulf Hansson
parent 2162d9f41e
commit af951761d0
2 changed files with 7 additions and 0 deletions
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2
drivers/mmc/host/sdhci.c
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@ -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;

5
drivers/mmc/host/sdhci.h
View File

@ -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 */