[PATCH 05/12] mmc: sdhci: add a pre voltage switch callback function

[Ziji Hu]

Hi Adrian,

  Thanks a lot for the suggestion. I'm from Marvell Xenon SDHC team.
  Most of sdhci host ops are still used in our driver. We just change or add few ops. Thus, if we create our own mmc_host_ops, many static sdhci host ops will be exported. I would like to know whether such a modification can be accepted or not.

   I notice that community is improving sdhci. Thus all the static sdhci ops called outside the sdhci.c will be exported. Is my understanding correct?
   Thank you.

Best regards,
Hu Ziji

>> 在 2016年6月13日，16:52，Adrian Hunter <adrian.hunter at intel.com> 写道：
>> 
>> On 09/06/16 10:10, Gregory CLEMENT wrote:
>> From: Victor Gu <xigu at marvell.com>
>> 
>> Some host controller such as Xenon needs additional setting when
>> switching signal voltage in eMMC mode. They also need to re-enable
>> internal clock before a voltage switch.
>> 
>> This commit adds a callback routine "voltage_switch_pre" in the struct
>> sdhci_ops, which is used by some host controllers which need re-enable
>> the internal clock before a voltage switch.
> 
> Don't want to add sdhci host ops for the "do something before a mmc host op"
> case.
> 
> Instead, export sdhci_start_signal_voltage_switch() and  hook
> host->mmc_host_ops.start_signal_voltage_switch. Then in sdhci-xenon.c:
> 
> int xenon__start_signal_voltage_switch(struct mmc_host *mmc,
>                      struct mmc_ios *ios)
> {
>   blah blah
>   return sdhci_start_signal_voltage_switch(mmc, ios);
> }
> 
> 
>> 
>> [gregory.clement at free-electrons.com: split the initial commit and
>> reformulate the log]
>> 
>> Signed-off-by: Victor Gu <xigu at marvell.com>
>> Signed-off-by: Marcin Wojtas <mw at semihalf.com>
>> Signed-off-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
>> ---
>> drivers/mmc/host/sdhci.c | 4 ++++
>> drivers/mmc/host/sdhci.h | 1 +
>> 2 files changed, 5 insertions(+)
>> 
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index b07219426d39..cad03ffa9d9b 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1729,6 +1729,10 @@ static int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
>>   if (host->version < SDHCI_SPEC_300)
>>       return 0;
>> 
>> +    /* Some controller need to do more before switching */
>> +    if (host->ops->voltage_switch_pre)
>> +        host->ops->voltage_switch_pre(host);
>> +
>>   ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>> 
>>   switch (ios->signal_voltage) {
>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>> index 49c6c5b0e33b..6bec1b0368d2 100644
>> --- a/drivers/mmc/host/sdhci.h
>> +++ b/drivers/mmc/host/sdhci.h
>> @@ -550,6 +550,7 @@ struct sdhci_ops {
>>                    unsigned int max_dtr, int host_drv,
>>                    int card_drv, int *drv_type);
>>   void    (*init_card)(struct sdhci_host *host, struct mmc_card *card);
>> +    void    (*voltage_switch_pre)(struct sdhci_host *host);
>> };
>> 
>> #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> 
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