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mmc: sdhci-esdhc-imx: disable clocks before changing frequency 

In the uSDHC case (e.g. i.MX 6) clocks only get disabled if frequency
is set to 0. However, it could be that the stack asks for a frequency
change while clocks are on. In that case the function clears the
divider registers (by clearing ESDHC_CLOCK_MASK) while the clock is
enabled! This causes a short period of time where the clock is
undivided (on a i.MX 6DL a clock of 196MHz has been measured).

For older IP variants the driver disables clock by clearing some bits
in ESDHC_SYSTEM_CONTROL.

Make sure to disable card clock before changing frequency for uSDHC
IP variants too.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Acked-by: Dong Aisheng <aisheng.dong@nxp.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
hifive-unleashed-5.1
Stefan Agner 2018-07-12 10:07:24 +02:00 committed by Ulf Hansson
parent 726df1d5a6
commit 73e736f865
1 changed files with 6 additions and 6 deletions
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12
drivers/mmc/host/sdhci-esdhc-imx.c
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@ -705,14 +705,14 @@ static inline void esdhc_pltfm_set_clock(struct sdhci_host *host,
int div = 1;
u32 temp, val;
if (esdhc_is_usdhc(imx_data)) {
val = readl(host->ioaddr + ESDHC_VENDOR_SPEC);
writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON,
host->ioaddr + ESDHC_VENDOR_SPEC);
}
if (clock == 0) {
host->mmc->actual_clock = 0;
if (esdhc_is_usdhc(imx_data)) {
val = readl(host->ioaddr + ESDHC_VENDOR_SPEC);
writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON,
host->ioaddr + ESDHC_VENDOR_SPEC);
}
return;
}