Re: [PATCH v9] mmc: support BKOPS feature for eMMC

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

Hi, Adrian,

On 06/14/2012 10:46 PM, Adrian Hunter wrote:

> On 08/06/12 07:39, Jaehoon Chung wrote:
>> Enable eMMC background operations (BKOPS) feature.
>>
>> If URGENT_BKOPS is set after a response, note that BKOPS
>> are required. After all I/O requests are finished, run
>> BKOPS if required. Should read/write operations be requested
>> during BKOPS, first issue HPI to interrupt the ongoing BKOPS
>> and then service the request.
>> If BKOPS-STATUS is upper than LEVEL2, need to check until clear
>> the BKOPS-STATUS vaule. 
>>
>> If you want to enable this feature, set MMC_CAP2_BKOPS.
>> And if you want to set the BKOPS_EN bit in ext_csd register,
>> use the MMC_CAP2_INIT_BKOPS.
>>
>> Future considerations
>>  * Check BKOPS_LEVEL=1 and start BKOPS in a preventive manner.
>>  * Interrupt ongoing BKOPS before powering off the card.
>>  * How get BKOPS_STATUS value.(periodically send ext_csd command?)
>>
>> Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
>> Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
>> Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>
>> Signed-off-by: Maya Erez <merez@codeaurora.org>
>> ---
> 
> I would not expect this to work nicely with runtime PM.  I expect that BKOPS
> would need to be stopped beforehand.  But that would limit the time
> available for BKOPS since runtime PM would always kick in and stop it.  How
> is runtime PM to be handled?

I think that add some function like the mmc_runtime_pm_suspend().
int mmc_runtime_pm_suspend()
{
	if running bkops {
		waiting for limit time..=> (when upper than Level2)
		otherwise don't wait
		stop-bkops
	} else
		nothing..
}
Almost runtime PM is controlled at host side.
So it's not very good that add the bkops control code at host side.
How about this? i want to get your opinion.

Best Regards,
Jaehoon Chung

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