On 05/26/2016 02:16 PM, 장민우 wrote:
> Hello, Jaehoon Chung.
>
> I mentioned "default speed mode" not hs200, hs400, ddr and hs mode.
Yes, default speed mode is not HS400, HS400, DDR..
You mean "default speed mode" is 26MHz?
As i know, default speed is 26MHz. and it used for initializing card.
>
> I think If "default speed mode" is set, there is no bus width change.
There is DEVICE_TYPE[196] at ext_csd register.
Device type should be selected one of them. (You can see the currently valid value.)
I don't know exactly what your purpose.
If i missed something, let me know in more detail about default speed, eMMC version, your environment.
Best Regards,
Jaehoon Chung
>
> If you have any advice to use "default speed mode" of the eMMC. please
> let me know.
>
> Thank you.
>
> Best Regards,
> Minwoo Jang.
>
> 2016-05-24 18:41 GMT+09:00 Jaehoon Chung <jh80.chung@xxxxxxxxxxx>:
>> Hi,
>>
>> On 05/24/2016 06:07 PM, 장민우 wrote:
>>> Dear linux-mmc.
>>>
>>> Hello, I'm Minwoo Jang.
>>>
>>> I have a question about using default speed of the eMMC.
>>>
>>> When default speed is used, mmc_select_bus_width() is never called.
>>>
>>> So, eMMC can not be set 4 bit or 8 bit bus width, I think.
>>>
>>> Please, give me your opinions on the following diff codes.
>>
>> In mmc_select_timing(), timing should be set to MMC_TIMING_HS or others.
>> Then mmc_select_bus_width() should be entered.
>>
>> Best Regards,
>> Jaehoon Chung
>>
>>>
>>> Thank you.
>>>
>>> =====================================================
>>>
>>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>>> index 94b4462..3b1cc4d 100644
>>> --- a/drivers/mmc/core/mmc.c
>>> +++ b/drivers/mmc/core/mmc.c
>>> @@ -952,6 +952,8 @@ static int mmc_select_bus_width(struct mmc_card *card)
>>>
>>> if (!err) {
>>> err = bus_width;
>>> + pr_warn("%s: switch to bus width %d\n",
>>> + mmc_hostname(host), (1 << bus_width));
>>> break;
>>> } else {
>>> pr_warn("%s: switch to bus width %d failed\n",
>>> @@ -1500,6 +1502,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
>>> if (err)
>>> goto err;
>>> }
>>> + } else {
>>> + /* Select the bus width for normal speed mode */
>>> + err = mmc_select_bus_width(card);
>>> + if (IS_ERR_VALUE(err)) {
>>> + pr_warn("%s: Selecting bus width failed\n",
>>> + mmc_hostname(card->host));
>>> + goto err;
>>> + }
>>> }
>>>
>>> Best regards,
>>>
>>> MW Jang.
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>>>
>>
>
>
>
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