On 18/10/16 15:04, Ziji Hu wrote:
> Hi Adrian,
> 
> On 2016/10/17 15:55, Adrian Hunter wrote:
>> On 12/10/16 15:17, Ziji Hu wrote:
>>> Hi Adrian,
>>>
>>> On 2016/10/11 20:39, Adrian Hunter wrote:
> <snip>
>>>>> +static int __xenon_emmc_delay_adj_test(struct mmc_card *card)
>>>>> +{
>>>>> + int err;
>>>>> + u8 *ext_csd = NULL;
>>>>> +
>>>>> + err = mmc_get_ext_csd(card, &ext_csd);
>>>>> + kfree(ext_csd);
>>>>> +
>>>>> + return err;
>>>>> +}
>>>>> +
>>>>> +static int __xenon_sdio_delay_adj_test(struct mmc_card *card)
>>>>> +{
>>>>> + struct mmc_command cmd = {0};
>>>>> + int err;
>>>>> +
>>>>> + cmd.opcode = SD_IO_RW_DIRECT;
>>>>> + cmd.flags = MMC_RSP_R5 | MMC_CMD_AC;
>>>>> +
>>>>> + err = mmc_wait_for_cmd(card->host, &cmd, 0);
>>>>> + if (err)
>>>>> +         return err;
>>>>> +
>>>>> + if (cmd.resp[0] & R5_ERROR)
>>>>> +         return -EIO;
>>>>> + if (cmd.resp[0] & R5_FUNCTION_NUMBER)
>>>>> +         return -EINVAL;
>>>>> + if (cmd.resp[0] & R5_OUT_OF_RANGE)
>>>>> +         return -ERANGE;
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static int __xenon_sd_delay_adj_test(struct mmc_card *card)
>>>>> +{
>>>>> + struct mmc_command cmd = {0};
>>>>> + int err;
>>>>> +
>>>>> + cmd.opcode = MMC_SEND_STATUS;
>>>>> + cmd.arg = card->rca << 16;
>>>>> + cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
>>>>> +
>>>>> + err = mmc_wait_for_cmd(card->host, &cmd, 0);
>>>>> + return err;
>>>>> +}
>>>>> +
>>>>> +static int xenon_delay_adj_test(struct mmc_card *card)
>>>>> +{
>>>>> + WARN_ON(!card);
>>>>> + WARN_ON(!card->host);
>>>>> +
>>>>> + if (mmc_card_mmc(card))
>>>>> +         return __xenon_emmc_delay_adj_test(card);
>>>>> + else if (mmc_card_sd(card))
>>>>> +         return __xenon_sd_delay_adj_test(card);
>>>>> + else if (mmc_card_sdio(card))
>>>>> +         return __xenon_sdio_delay_adj_test(card);
>>>>> + else
>>>>> +         return -EINVAL;
>>>>> +}
>>>>
>>>> So you are issuing commands from the ->set_ios() callback.  I would want to
>>>> get Ulf's OK for that before going further.
>>>>
>>>     Yes, you are correct.
>>>     In some speed mode, Xenon SDHC has to send a series of transfers to 
>>> search for a perfect sampling point in PHY delay line.
>>>     It is like tuning process.
>>>
>>>> One thing: you will need to ensure you don't trigger get HS400 re-tuning
>>>> because it will call back into ->set_ios().
>>>>
>>>     Could you please make the term "HS400 re-tuning" more detailed?
>>>     In current MMC driver, "HS400 re-tuning" will go back to HS200, execute 
>>> HS200 tuning and come back to HS400.
>>>     I'm sure our Xenon SDHC will not execute it.
>>
>> Currently, re-tuning is automatically enabled whenever tuning is executed,
>> and then re-tuning will be done periodically or after CRC errors.  The
>> function to disable re-tuning mmc_retune_disable() is not exported, however
>> if you have you are determining the sampling point your own way, you could
>> simply not implement ->execute_tuning() and then there would be no tuning
>> and no re-tuning.
>>
> 
>       It is a little complex in our Xenon SDHC.
>       For the speed mode which requests tuning, such as SDR104 and HS200, our 
> driver will execute standard tuning as spec requires.
>       However, for those speed mode in which tuning is not requested in spec, 
> our driver has to issues commands to search for the best sampling point.
>       
>       It seems that HS400 re-tuning/tuning is disabled by default. Is it 
> correct?

No, it is enabled by default - there is currently no periodic re-tuning  for
HS400 but CRC errors or runtime suspend / resume will cause re-tuning.

> 
>>>
>>>     However, in coming eMMC 5.2, there is a real HS400 re-tuning, in which 
>>> tuning can be directly executed in HS400 mode.
>>>     Our Xenon SDHC will neither trigger this HS400 re-tuning.
>>>     But since so far there is no such feature in MMC driver, I cannot give 
>>> you a 100% guarantee now.
>>>
>>>> And you have the problem that you need to get a reference to the card 
>>>> before
>>>> the card device has been added.  As I wrote in response to the previous
>>>> patch, you should get Ulf's help with that too.
>>>>
>>>     Sure.
>>>     I will get card_candidate solved at first.
>>>     Thank you again for your review and help.
>>>
>>>     Thank you.
>>>
>>> Best regards,
>>> Hu Ziji
>>>>
>>>
>>
> 

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