On 08/31/2016 04:13 PM, Shawn Lin wrote:
> On 2016/8/31 13:51, Jaehoon Chung wrote:
>> HS400 mode doesn't need to do execute_tuning, because it's already
>> tuned in HS200 mode. And Tuning command is optional for UHS50 mode.
>>
>> In future, the general execute_tuning sequence can be included in this
>> function.
>
> Maybe this isn't what we want for mmc.
>
> I see both of sd and sdio call mmc_execute_tuning by checking
> the ios.timing, and explicitly we need to do tuning for
> MMC_TIMING_UHS_SDR50 as the mmc core asks we to do that.
>
> Moreover, why mmc didn't do something like:
>
> if (card->host->ios.timing == MMC_TIMING_XXXXX || ....)
> mmc_execute_tuning()
>
> So we don't need every host driver to add these check and I do
> see some host drivers check these timing for their execute_tuning
> callback..
>
> What is your opinion? :)
Yep, your comment makes sense..So i'm checking SD specification.
I think it needs to know which UHS card is..(UHS50 or UHS104)..
But current kernel can't distinguish these..
According to spec, we can distinguish UHS50 and UHS104 with TRAN_SPEED field.
"UHS50 Card set TRANS_SPEED to 0Bh (100Mbit/sec), for both SDR50 and DDR50 modes.
UHS104 Card set TRAN_SPEED to 2Bh (200Mbit/sec)"
I'm not sure it's helpful to me...but i will consider more...
Thanks you for comment. :)
Best Regards,
Jaehoon Chung
>
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@xxxxxxxxxxx>
>> ---
>> drivers/mmc/host/dw_mmc.c | 17 ++++++++++++++++-
>> 1 file changed, 16 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>> index 22dacae..6571924 100644
>> --- a/drivers/mmc/host/dw_mmc.c
>> +++ b/drivers/mmc/host/dw_mmc.c
>> @@ -1568,10 +1568,25 @@ static int dw_mci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>> struct dw_mci_slot *slot = mmc_priv(mmc);
>> struct dw_mci *host = slot->host;
>> const struct dw_mci_drv_data *drv_data = host->drv_data;
>> - int err = -EINVAL;
>> + int err = 0;
>> +
>> + switch (host->timing) {
>> + case MMC_TIMING_MMC_HS400:
>> + err = -EINVAL;
>> + goto out;
>> + case MMC_TIMING_MMC_HS200:
>> + case MMC_TIMING_UHS_SDR104:
>> + case MMC_TIMING_UHS_DDR50:
>> + break;
>> + case MMC_TIMING_UHS_SDR50:
>> + /* Fall through */
>> + default:
>> + goto out;
>> + }
>>
>> if (drv_data && drv_data->execute_tuning)
>> err = drv_data->execute_tuning(slot, opcode);
>> +out:
>> return err;
>> }
>>
>>
>
>
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