Re: [PATCH V6 02/15] mmc: core: Enable / disable re-tuning

Adrian Hunter
2015-04-21T10:40:03Z

On 21/04/15 11:59, Ulf Hansson wrote:
> On 20 April 2015 at 14:09, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> Enable re-tuning when tuning is executed and
>> disable re-tuning when card is no longer initialized.
>>
>> In the case of SDIO suspend, the card can keep power.
>> In that case, re-tuning need not be disabled, but ensure
>> the re-tuning timer is disabled.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>> drivers/mmc/core/core.c | 4 ++++
>> drivers/mmc/core/sdio.c | 2 ++
>> 2 files changed, 6 insertions(+)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index c296bc0..dd43f9b 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -1109,6 +1109,8 @@ int mmc_execute_tuning(struct mmc_card *card)
>>
>> if (err)
>> pr_err("%s: tuning execution failed\n", mmc_hostname(host));
>> + else
>> + mmc_retune_enable(host);
>>
>> return err;
>> }
>> @@ -1140,6 +1142,8 @@ void mmc_set_bus_width(struct mmc_host *host, unsigned int width)
>> */
>> void mmc_set_initial_state(struct mmc_host *host)
>> {
>> + mmc_retune_disable(host);
>> +
>> if (mmc_host_is_spi(host))
>> host->ios.chip_select = MMC_CS_HIGH;
>> else
>> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
>> index 5bc6c7d..ee7bfd4 100644
>> --- a/drivers/mmc/core/sdio.c
>> +++ b/drivers/mmc/core/sdio.c
>> @@ -936,6 +936,8 @@ static int mmc_sdio_suspend(struct mmc_host *host)
>>
>> if (!mmc_card_keep_power(host))
>> mmc_power_off(host);
>> + else
>> + mmc_retune_timer_stop(host);
>>
>
> We also need to re-start the timer at the end of mmc_sdio_resume() in
> case of mmc_card_keep_power().

It seems to me if a timer is being used, and the suspend can last an
arbitrary length of time, then the safe thing to do is to re-tune after
resume. i.e.

if (!mmc_card_keep_power(host)) {
mmc_power_off(host);
} else if (host->host->retune_period) {
mmc_retune_timer_stop(host);
mmc_retune_needed(host);
}

That is what sdhci has to do anyway.

>
>> return 0;
>> }
>> --
>> 1.9.1
>>
>> --
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>
> Kind regards
> Uffe
>
>