On Wed, Nov 13, 2013 at 7:18 PM, Arend van Spriel <arend@xxxxxxxxxxxx> wrote:
> On 11/13/2013 12:12 PM, Dong Aisheng wrote:
>>
>> Hi Arend,
>>
>> On Wed, Nov 13, 2013 at 6:21 PM, Arend van Spriel <arend@xxxxxxxxxxxx>
>> wrote:
>>>
>>> On 11/13/2013 06:02 AM, Dong Aisheng wrote:
>>>>
>>>>
>>>> Hi Arend,
>>>>
>>>> On Mon, Nov 11, 2013 at 5:49 PM, Arend van Spriel <arend@xxxxxxxxxxxx>
>>>> wrote:
>>>>>
>>>>>
>>>>> When the host->tuning_count is zero it means that the
>>>>> retuning is disabled. This is checked on the first
>>>>> run of sdhci_execute_tuning() by the if statement below:
>>>>>
>>>>> if (!(host->flags & SDHCI_NEEDS_RETUNING) &&
>>>>> host->tuning_count
>>>>> &&
>>>>> (host->tuning_mode == SDHCI_TUNING_MODE_1)) {
>>>>>
>>>>> So only when tuning_count is non-zero it will set the host
>>>>> flag SDHCI_USING_RETUNING_TIMER. The else statement is only
>>>>> for re-programming the timer, which means that flag must be
>>>>> set. Because that is not checked the else statement is executed
>>>>> in the first run when tuning_count is zero.
>>>>>
>>>>> This was seen on a host controller which indicated
>>>>> SDHCI_TUNING_MODE_1 (0) and tuning_count being zero. Suspect
>>>>> that (one of) these registers is not properly set.
>>>>>
>>>>> Signed-off-by: Arend van Spriel <arend@xxxxxxxxxxxx>
>>>>> ---
>>>>> This patch applies to the mmc-next branch.
>>>>>
>>>>> V2:
>>>>> - add more explanation to the commit message
>>>>> - check host flag SDHCI_USING_RETUNING_TIMER
>>>>> ---
>>>>> drivers/mmc/host/sdhci.c | 2 +-
>>>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>
>>>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>>>> index bd8a098..5974599 100644
>>>>> --- a/drivers/mmc/host/sdhci.c
>>>>> +++ b/drivers/mmc/host/sdhci.c
>>>>> @@ -2014,7 +2014,7 @@ out:
>>>>> host->tuning_count * HZ);
>>>>> /* Tuning mode 1 limits the maximum data length to
>>>>> 4MB
>>>>> */
>>>>> mmc->max_blk_count = (4 * 1024 * 1024) /
>>>>> mmc->max_blk_size;
>>>>> - } else {
>>>>> + } else if (host->flags & SDHCI_USING_RETUNING_TIMER) {
>>>>> host->flags &= ~SDHCI_NEEDS_RETUNING;
>>>>> /* Reload the new initial value for timer */
>>>>> if (host->tuning_mode == SDHCI_TUNING_MODE_1)
>>>>
>>>>
>>>>
>>>> I wonder if we could also remove this line?
>>>> It looks to me it's not neccesary to check the tuning_mode again since
>>>> we already check the flag
>>>> above and SDHCI_TUNING_MODE_1 seems like the prerequisite of
>>>> SDHCI_USING_RETUNING_TIMER.
>>>
>>>
>>>
>>> According the spec the other tuning modes also can use retuning timer.
>>> Currently, the mmc stack in upstream linux only supports tuning mode 1.
>>> When
>>> adding the other modes this if statement will probably go.
>>>
>>
>> For currently code, it looks like also not necessary to check it since
>> SDHCI_USING_RETUNING_TIMER will only be set when tunning_mode is
>> SDHCI_TUNING_MODE_1.
>> And SDHCI_TUNING_MODE_1 just indicates the tuning mode while the flag
>> SDHCI_USING_RETUNING_TIMER represents the retuning timer implementation.
>> So check the flag to invoke the timer seems make more sense to me.
>> do you agree?
>
>
> The flag SDHCI_USING_RETUNING_TIMER is only set after the initial tuning run
> so in the if-statement. So currently in the else-statement the fact that
> SDHCI_USING_RETUNING_TIMER is set implies SDHCI_TUNING_MODE_1.
>
Right, so that means we could remove the tuning_mode check in the
else-statement.
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 2d55e6a..b2928ef 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2015,12 +2015,11 @@ out:
host->tuning_count * HZ);
/* Tuning mode 1 limits the maximum data length to 4MB */
mmc->max_blk_count = (4 * 1024 * 1024) / mmc->max_blk_size;
- } else {
+ } else if (host->flags & SDHCI_USING_RETUNING_TIMER) {
host->flags &= ~SDHCI_NEEDS_RETUNING;
/* Reload the new initial value for timeout workqueue */
- if (host->tuning_mode == SDHCI_TUNING_MODE_1)
- schedule_delayed_work(&host->tuning_timeout_work,
- host->tuning_count * HZ);
+ schedule_delayed_work(&host->tuning_timeout_work,
+ host->tuning_count * HZ);
}
/*
Regards
Dong Aisheng
>
> Regards,
> Arend
>
>> Regards
>> Dong Aisheng
>>
>>> Regards,
>>> Arend
>>>
>>>
>>>> Regards
>>>> Dong Aisheng
>>>>
>>>>> --
>>>>> 1.7.10.4
>>>>>
>>>>>
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>>>>
>>>>
>>>>
>>>
>>>
>>
>
>
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