On 11/28/11, Jaehoon Chung <jh80.ch...@samsung.com> wrote:
> Hi Kostya
>
> On 11/28/2011 06:39 PM, Konstantin Dorfman wrote:
>
>> Hello Jaehoon, Per
>>
>> I have experimented with eMMC v4.41 card and BKOPS feature and want to add
>> info on EXT_CSD_BKOPS_EN[163] field. See below.
>>
>>> Hi Per
>>>
>>>>>>>>>
>>>>>>>>> if (card->ext_csd.rev >= 5) {
>>>>>>>>> + /* check whether the eMMC card support BKOPS */
>>>>>>>>> + if (ext_csd[EXT_CSD_BKOPS_SUPPORT] & 0x1) {
>>>>>>>>> + card->ext_csd.bkops = 1;
>>>>>>>>> + card->ext_csd.bkops_en = 1;
>>>>>>>> What if the card has not enabled bkops? This bit could be unset.
>>>>>>>> card->ext_csd.bkops_en = ext_csd[EXT_CSD_BKOPS_EN];
>>>>>>> When card is supported the bkops, bkops_en bit is set by default...
>>>>>>>
>>>>>> How do you know if the bkops_en is really enabled in th ext_csd?
>>>>>> It could be unset in the ext_csd, right?
>>>>>
>>>>> In emmc4.5 spec, if card is supported the bkops, bkops_en is set by
>>>>> default.
>>>> If bkops_en is set by default it should be in the the ext_csd too,
>>>> right?
>>>> It should be safer to trust the value of ext_csd[EXT_CSD_BKOPS_EN] in
>>>> this case I think.
>>>
>>> If we want to ensure whether bkops_en bit is set or not, your approach is
>>> right.
>>>
>>> Best Regards,
>>> Jaehoon Chung
>>
>> First of all protocol state:
>> ------------------------------
>> 7.4.57 BKOPS_EN [163]
>> This field allows the _host_ to indicate to the device if it is expected
>> to periodically manually start background operations by writing to the
>> BKOPS_START field.
>>
>> ...In order for the device to know if host is going to periodically start
>> background operations, host shall set bit 0 of BKOPS_EN (EXT_CSD byte
>> [163]) to indicate that it is going to write to BKOPS_START periodically.
>> The device may then delay some of its maintenance operations to when host
>> writes to BKOPS_START.
>> ------------------------------
>>
>> My card supports BKOPS (by reading Bit 0 of BKOPS_SUPPORT (EXT_CSD byte
>> [502]), but BKOPS_EN[163] is not set. So I suppose, original code to set
>> BKOPS_EN[163] is needed, otherwise card will never delay its maintenance
>> operations.
>
>
> Ok...i will add the code for setting BKOPS_EN bit in patch-v4.
I hope this features are provided from platform data. since it's not
mandatory for all devices
Thank you,
Kyungmin Park
> Thanks,
> Jaehoon Chung
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