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List:       linux-mmc
Subject:    Re: [PATCH v2] mmc: Resolve BKOPS compatability issue
From:       Ulf Hansson <ulf.hansson () linaro ! org>
Date:       2015-01-30 10:25:07
Message-ID: CAPDyKFrR2jne1C=R2phfesLMuZDhARiQgZxvkAcMHkMVrGXaiA () mail ! gmail ! com
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On 30 January 2015 at 08:26, Jaehoon Chung <jh80.chung@samsung.com> wrote:
> Hi, Alexey.
>
> On 01/29/2015 05:49 PM, Alexey Skidanov wrote:
>> This patch is coming to fix compatibility issue of BKOPS_EN  field of EXT_CSD.
>> In eMMC-5.1, BKOPS_EN was changed, and now it has two operational bits:
>> Bit 0 - MANUAL_EN
>> Bit 1 - AUTO_EN
>> In previous eMMC revisions, only Bit 0 was supported.
>
> If "manual enable" is the same functionality with previous enable,
> I think it doesn't need to change the name..
> Just checking whether enable or not with Mask bit?
>
> If need to add the auto enable, only add the bkops_auto_en in future.
> This is just my preference..and i don't read the spec since i don't have eMMC5.1 spec.
>
> If manual-enable is difference with previous enable, how about using bkops-manual-en?

According to information I have got around the eMMC 5.1 spec, the old
value of MAN_EN will remain. That also means that bit will remain as
one time programmable.

The new AUTO_EN bit, will be multiple writeable with value kept after
power failure. But more importantly, the card seems to expect the host
to disable AUTO_EN before power failure. In other words we need to
disable AUTO_EN (if set) before entering system PM state an cutting
power to the card.

So, yes, we will have to deal with AUTO_EN sooner or later, thus I am
kind of happy Alexey's patch, as is.

Kind regards
Uffe
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