Re: [PATCH 06/10] mmc: sdhci: Add get_clk_div callback support

[Ritesh Harjani <riteshh@codeaurora.org>]

Hi Jaehoon/Adrian,


On 8/12/2016 7:04 AM, Jaehoon Chung wrote:
> Hi,
>
> On 08/11/2016 10:52 PM, Ritesh Harjani wrote:
>> Few controllers (like MSM) may have to override div
>> in certain cases. Hence provide a callback to get the
>> div value for their driver.
>>
>> Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
>> Signed-off-by: Ritesh Harjani <riteshh@codeaurora.org>
>> ---
>>  drivers/mmc/host/sdhci.c | 8 ++++++++
>>  drivers/mmc/host/sdhci.h | 1 +
>>  2 files changed, 9 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index cd65d47..cc3d6f2 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1318,6 +1318,14 @@ u16 sdhci_calc_clk(struct sdhci_host *host, unsigned int clock,
>>  clock_set:
>>  	if (real_div)
>>  		*actual_clock = (host->max_clk * clk_mul) / real_div;
>> +	/*
>> +	 * Few controllers may have to override div
>> +	 * here. Hence provide a callback to get the
>> +	 * div value for them.
>> +	 */
>> +	if (host->ops->get_clk_div)
>> +		div = host->ops->get_clk_div(host, div);
>
> This is for only getting your div value. Few controllers?
> Rather, use the existent callback function..It's better than adding new callback.

As of today sdhci-of-arasan is the only user of this quirk 
-SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN. I was hoping that with this 
callback, we may get away with this quirk if sdhci-of-arasan can have 
get_clk_div callback implemented in it's driver?

Since I was not sure on this, so I did not modify sdhci-of-arasan. Thoughts?

>
> In your controller, add the your set_clock() callback. not get_clk_div.
> (Well, Adrian might have other opinion.)
Alright, please let me know what would be the right approach.

>
> Best Regards,
> Jaehoon Chung
>
>
>> +
>>  	clk |= (div & SDHCI_DIV_MASK) << SDHCI_DIVIDER_SHIFT;
>>  	clk |= ((div & SDHCI_DIV_HI_MASK) >> SDHCI_DIV_MASK_LEN)
>>  		<< SDHCI_DIVIDER_HI_SHIFT;
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index 0411c9f..4701001 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -562,6 +562,7 @@ struct sdhci_ops {
>>  					 struct mmc_card *card,
>>  					 unsigned int max_dtr, int host_drv,
>>  					 int card_drv, int *drv_type);
>> +	int	(*get_clk_div)(struct sdhci_host *host, int div);
>>  };
>>
>>  #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
>>
>