Hi Ulf,
2014-09-11 13:03 GMT+02:00 Ulf Hansson <ulf.hansson@xxxxxxxxxx>:
> On 9 September 2014 16:21, Johan Rudholm <johan.rudholm@xxxxxxxx> wrote:
>> SD-cards cannot be reset, but they can be power cycled. Power cycling
>> a buggy SD-card sometimes helps it get back on track.
>
> Hi Johan,
>
> This feature has been missing for too long - really great that you are
> working on this!
>
>>
>> Signed-off-by: Johan Rudholm <johanru@xxxxxxxx>
>> ---
>> drivers/mmc/core/core.c | 16 +++++++++++-----
>> 1 files changed, 11 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index d03a080..9171aa9 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -2250,19 +2250,25 @@ static int mmc_do_hw_reset(struct mmc_host *host, int check)
>> {
>> struct mmc_card *card = host->card;
>>
>> - if (!(host->caps & MMC_CAP_HW_RESET) || !host->ops->hw_reset)
>> - return -EOPNOTSUPP;
>> -
>> if (!card)
>> return -EINVAL;
>>
>> - if (!mmc_can_reset(card))
>> + if (!mmc_card_sd(card) && !((host->caps & MMC_CAP_HW_RESET) &&
>> + host->ops->hw_reset))
>> + return -EOPNOTSUPP;
>> +
>> + if (!mmc_card_sd(card) && !mmc_can_reset(card))
>> return -EOPNOTSUPP;
>>
>> mmc_host_clk_hold(host);
>> mmc_set_clock(host, host->f_init);
>>
>> - host->ops->hw_reset(host);
>> + if (mmc_card_sd(card))
>> + mmc_power_cycle(host, card->ocr);
>> + else
>> + host->ops->hw_reset(host);
>> +
>> + pr_warning("%s: reset device\n", mmc_hostname(host));
>>
>> /* If the reset has happened, then a status command will fail */
>> if (check) {
>> --
>> 1.7.2.5
>>
>
> Before we decide to go ahead an continue to hack on the current reset
> code as your patch does, could you possibly consider to do some more
> extensive rework this code?
Sure, challenge accepted!
> Here are some of the ideas that I had in mind.
>
> 1) Invent a new bus_ops callback for reset. Or maybe we should re-use
> the ->power_save|restore ones, since those already exist!?
> 2) Since those bus_ops are specific for sd/mmc/sdio we shall handle
> those related parts in there.
> 3) Then let's mmc_do_hw_reset invoke the above bus_ops.
> 4) Remove the mmc_hw_reset_check() API. Currently only used by mmc_test.
Reuse makes some sense, since bus_ops->power_restore is already a part
of the current hw_reset reset sequence. But do you mean like letting
bus_ops->power_save call host_ops->hw_reset? Won't this interfere with
the other use case of power_save?
What's the current status of mmc_power_save_host and
bus_ops->power_save anyway? As far as I can see, they are no longer
used by the MMC framework. Maybe we can throw away mmc_power_save_host
and bus_ops->power_save, and instead add the reset bus_ops? The naming
of the bus_ops will be more fitting this way.
//Johan
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