linux-kernel - Re: [PATCH] mmc: core: add auto bkops support

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Message-ID: <CAPDyKFpLEcXmYK9AM-WLt3_ehLPCx7-DgmVwKfA6f2OuKkGYTg@mail.gmail.com>
Date:	Wed, 22 Jun 2016 17:03:57 +0200
From:	Ulf Hansson <ulf.hansson@...aro.org>
To:	Alex Lemberg <Alex.Lemberg@...disk.com>
Cc:	Adrian Hunter <adrian.hunter@...el.com>,
	Shawn Lin <shawn.lin@...k-chips.com>,
	Jaehoon Chung <jh80.chung@...sung.com>,
	linux-mmc <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Doug Anderson <dianders@...omium.org>,
	"open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH] mmc: core: add auto bkops support

[...]

>>> >From my first impression I agree, as that is the policy we have been
>>>>sticking to when writing to persistent EXT_CSD registers.
>>>>Although, in this case, I am actually wondering on what is the best approach.
>>>>
>>>>Is there really ever a case when we don't want auto BKOPS to be default enabled?
>>>>I think BKOPS is a fundamental feature of an FTL and I can't see a
>>>>reason to why we need to involve mmc-utils/userspace to enable it. Am
>>>>I wrong?
>>>
>>> The even worst case is – involve mmc-utils/userspace to DISABLE it.
>>> I think this register need to be set by vendor and no need to be changed on runtime.
>>
>>If it is set by the Vendor, that's of course the best.
>
> It can be set by Storage Vendor.
> According to the spec, the default value of this bit is vendor specific.
>
>>
>>Are you saying that we shouldn't enable it during the card init
>>sequence from the kernel, in case it is disabled?
>
> No.
> By the spec – a Host that wants to enable the device to perform
> background operations during device idle time, should signal the
> device by setting AUTO_EN in BKOPS_EN field [EXT_CSD byte 163] to 1b.

Okay, thanks!

Kind regards
Uffe