Re: [PATCH] sdhci: expose the SDCLK frq in sys ios

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Hello Adrian

On 10/20/2011 8:22 AM, Adrian Hunter wrote:
> On 19/10/11 16:45, Giuseppe CAVALLARO wrote:
>> This patch is to expose the SDCLK frequency in the ios /sys entry.
>>
>> For example, if the max clk for a normal speed card is 20MHz
>> this will be reported in /sys/kernel/debug/mmc0/ios instead of
>> the real SDCLK frequency (calculated as Baseclock / divisor;
>> divisor used for programming the Clock Control Register).
>>
>> Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@xxxxxx>
>> ---
>>  drivers/mmc/host/sdhci.c |    9 ++++++++-
>>  1 files changed, 8 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index 0e02cc1..6bdf64f 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1045,6 +1045,7 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>>  	int div = 0; /* Initialized for compiler warning */
>>  	u16 clk = 0;
>>  	unsigned long timeout;
>> +	unsigned int new_hc_clock = host->max_clk;
>>  
>>  	if (clock == host->clock)
>>  		return;
>> @@ -1134,7 +1135,10 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
>>  	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
>>  
>>  out:
>> -	host->clock = clock;
>> +	if (div)
>> +		new_hc_clock = host->max_clk / div;
> 
> At this point div is the value written to the register not the
> divisor

Hmm, you are right. I'll fix it.

>> +
>> +	host->clock = new_hc_clock;
>>  }
>>  
>>  static void sdhci_set_power(struct sdhci_host *host, unsigned short power)
>> @@ -1293,6 +1297,9 @@ static void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>>  
>>  	sdhci_set_clock(host, ios->clock);
>>  
>> +	/* Clock provided to the HC */
>> +	ios->clock = host->clock;
> 
> It would be nicer to keep ios->clock as the target
> frequency and add a new member to struct mmc_host for
> the actual frequency.

Why not! I like it. I'll rework the patch and send it again.
Just a question: do I have to dump both in /sys/.../ios?
If yes, maybe it's worth using: card_clock and hc_clock as names.
What do you think?

Regards
Peppe

> 
>> +
>>  	if (ios->power_mode == MMC_POWER_OFF)
>>  		sdhci_set_power(host, -1);
>>  	else
> 
> 

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