Re: [PATCH v2] mmc: dw-mmc: relocate the position called dw_mci_setup_bus()

[Jaehoon Chung <jh80.chung@samsung.com>]

Dear Seungwon,

On 10/30/2012 02:27 PM, Seungwon Jeon wrote:
> Monday, October 29, 2012, Jaehoon Chung <jh80.chung@samsung.com> wrote:
>> On 10/29/2012 06:08 PM, Seungwon Jeon wrote:
>>> Monday, October 29, 2012, Jaehoon Chung <jh80.chung@samsung.com>
>>>> After power-on, must be ensured at least 74~80 clocks before sending any first command.
>>>> To ensure, it's good that dw_mci_setup_bus() is located at dw_mci_set_ios
>>>> instead of __dw_mci_start_request()
>>> After power-up, host driver sets 'DW_MMC_CARD_NEED_INIT' flag, right?
>>> And then, this flag help to add SDMMC_CMD_INIT flag into CMD, when __dw_mci_start_request is
>> executed.
>>> 74~80 clocks is ensured with SDMMC_CMD_INIT regardless location change, isn't it?
>>> I mentioned this part in previous mail. Could you check it?
>> According to eMMC spec, after power-on, need to wait for 74-clock before sending first command
>> You can see code that after mmc_set_ios(), waiting for mmc_delay(10) into mmc_power_up().
>> (You can read the comment at mmc_power_up(), Maybe mmc_delay(10) didn't ensure the 74-clock).
> There is 'send_initialization' bit in CMD register.
> If this bit set with CMD0, it will guarantee 80 clocks by host controller.
Is it guaranteed 80-clocks by host-controller? So I understood something wrong.
My understanding is that "if flags is set, need to wait for 80-clock."
If host-controller can ensure the 80-clock, location is not important.

My point was just entire sequence with core.c and dw_mmc.c
Anyway, thank you for review.
If i miss other thing. let me know, plz.

Best Regards,
Jaehoon Chung

> Currently this is applied in driver.
> I agree change the location of dw_mci_setup_bus.
> But commit message seem not proper for it.
> Please let me know, if I miss something.
> 
> Thanks,
> Seungwon Jeon
>>
>> Best Regards,
>> Jaehoon Chung
>>>
>>> Thanks,
>>> Seungwon Jeon
>>>
>>>>
>>>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>>>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>>>> Acked-by: Seungwon Jeon <tgih.jun@samsung.com>
>>>> ------
>>>> Changelog V2:
>>>> 	- Modified the commit-message.
>>>> ---
>>>>  drivers/mmc/host/dw_mmc.c |    6 +++---
>>>>  1 files changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
>>>> index 4b2bedc..de79093 100644
>>>> --- a/drivers/mmc/host/dw_mmc.c
>>>> +++ b/drivers/mmc/host/dw_mmc.c
>>>> @@ -682,9 +682,6 @@ static void __dw_mci_start_request(struct dw_mci *host,
>>>>  	if (host->pdata->select_slot)
>>>>  		host->pdata->select_slot(slot->id);
>>>>
>>>> -	/* Slot specific timing and width adjustment */
>>>> -	dw_mci_setup_bus(slot);
>>>> -
>>>>  	host->cur_slot = slot;
>>>>  	host->mrq = mrq;
>>>>
>>>> @@ -810,6 +807,9 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
>>>>  	if (slot->host->drv_data->set_ios)
>>>>  		slot->host->drv_data->set_ios(slot->host, ios);
>>>>
>>>> +	/* Slot specific timing and width adjustment */
>>>> +	dw_mci_setup_bus(slot);
>>>> +
>>>>  	switch (ios->power_mode) {
>>>>  	case MMC_POWER_UP:
>>>>  		set_bit(DW_MMC_CARD_NEED_INIT, &slot->flags);
>>>> --
>>>> 1.7.4.1
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