Re: [PATCH] mmc: core: Optimize boot time by detecting cards simultaneously

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

Hi,

On 12/18/2015 06:49 AM, Ulf Hansson wrote:
> On 17 December 2015 at 20:47, Alan Cooper <alcooperx@gmail.com> wrote:
>> On Wed, Dec 16, 2015 at 4:07 AM, Ulf Hansson <ulf.hansson@linaro.org> wrote:
>>> To find the improved card detection times, I just used the kernel boot
>>> log and checked the time stamps for when the cards get detected. I ran
>>> the tests ~10 times and picked up some average values.
>>>
>>> To notice the improvement you need at least two cards to be inserted
>>> during boot. Perhaps you have a platform with one eMMC and one SD card
>>> slot, you can test.
>>
>> I tested the patch on one of our ARM bases SoC's. The SoC has an SD
>> card slot on the first controller and an eMMC device on the second
>> controller. I found ~100ms improvement on the time it took for the
>> rootfs on the eMMC device to be ready for use. Interestingly, I did
>> see the SD/eMMC order swap once in 20 tries. This is not an issue for
>> us as we already have to use UUID for the eMMC rootfs in case an SD
>> card is installed.
>>
>> Al
> 
> Al, thanks for your effort in testing. I assume I can apply a
> tested-by tag for that!
> 
> BTW, if you want to see an even better improvement, just find a
> crappier SD card as I guess you have a quite good one. :-)

I didn't test with this yet..actually, i have tested with only one board(Exynos4412).
There is no the changing index. (Not too much for testing)
but in my experiment, our platform(Tizen) should be produced the problem in SD-card case.
I need to check with SystemFW guys. I will check this..ASAP. 

Best Regards,
Jaehoon Chung

> 
> Kind regards
> Uffe
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