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SubjectRe: [PATCH] mmc: sdhci-esdhc-imx: disable clocks before changing frequency
On 11 July 2018 at 14:29, Adrian Hunter <adrian.hunter@intel.com> wrote:
> On 05/07/18 14:39, Stefan Agner wrote:
>> 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 chainging frequency for uSDHC
>
> chainging -> changing
>
>> IP variants too. Also fix indent to make disable/enable clock look
>> alike.
>>
>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>> ---
>> drivers/mmc/host/sdhci-esdhc-imx.c | 14 +++++++-------
>> 1 file changed, 7 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
>> index 85fd5a8b0b6d..aa48f4b2541a 100644
>> --- a/drivers/mmc/host/sdhci-esdhc-imx.c
>> +++ b/drivers/mmc/host/sdhci-esdhc-imx.c
>> @@ -708,14 +708,14 @@ 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;
>> }
>>
>> @@ -761,7 +761,7 @@ static inline void esdhc_pltfm_set_clock(struct sdhci_host *host,
>> 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);
>> + host->ioaddr + ESDHC_VENDOR_SPEC);
>
> Ideally each patch does only 1 thing. Please make white-space fix-up a
> separate patch.
>
>> }
>>
>> mdelay(1);
>>
>

It turned out that I had already applied this one. I am going to
re-base my next branch next week, so dropping the patch by then.

Until then, the patch is reverted.

Stefan, please send a new version addressing Adrian's comments.

Kind regards
Uffe

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