Re: [PATCH] sdhci: do not program timer when tuning_count is zero

["Arend van Spriel" <arend@broadcom.com>]

On 11/08/2013 07:50 AM, Aaron Lu wrote:
> On 11/07/2013 06:59 PM, Arend van Spriel wrote:
>> When the host->tuning_count is zero it means that the
>
> If the tuning_count is zero, then the retuning timer shouldn't be
> started in the first place and not possible to run code there. Or is the
> tuning_count dynamically changed?

Actually, the sdhci_execute_tuning() must run once to do the initial 
tuning procedure. This is mandatory for SDR104. However, *re*tuning is 
not and a zero tuning_count disables it.

The function is executed initially. The 'if' statement above the patched 
'else' statement is actually responsible for programming the retuning 
timer for the first time. However, it requires tuning_count to be 
non-zero. The 'else' statement is actually for reloading the retuning 
timer, which is not the case. Adding the non-zero check assures the 
retuning timer is never started.

I guess the fact that this needs explaining indicates that the commit 
message should be updated. I will send a V2 for this.

Regards,
Arend

> Thanks,
> Aaron
>
>> retuning is disabled. Doing a mod_timer() with a zero
>> tuning_count does something else.
>>
>> Signed-off-by: Arend van Spriel <arend@broadcom.com>
>> ---
>>   drivers/mmc/host/sdhci.c |    3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 7a7fb4f..9803e7a 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -2007,7 +2007,8 @@ out:
>>   	} else {
>>   		host->flags &= ~SDHCI_NEEDS_RETUNING;
>>   		/* Reload the new initial value for timer */
>> -		if (host->tuning_mode == SDHCI_TUNING_MODE_1)
>> +		if (host->tuning_count &&
>> +		    host->tuning_mode == SDHCI_TUNING_MODE_1)
>>   			mod_timer(&host->tuning_timer, jiffies +
>>   				host->tuning_count * HZ);
>>   	}
>>
>
>