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

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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>
This commit is contained in:
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;
}