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From:   Ulf Hansson <ulf.hansson@linaro.org>
Date:   Mon, 10 May 2021 11:44:10 +0200
Message-ID: <CAPDyKFqQe5aYqF6iNppY66EfkVNPce_sRF6NJgSn26Rs=_=jxw@mail.gmail.com>
Subject: Re: [PATCH 0/2] mmc: core: Implement support for cache ctrl for SD cards
To:     Avri Altman <Avri.Altman@wdc.com>
Cc:     "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Wolfram Sang <wsa+renesas@sang-engineering.com>,
        Shawn Lin <shawn.lin@rock-chips.com>,
        Masami Hiramatsu <masami.hiramatsu@linaro.org>,
        "linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Mon, 10 May 2021 at 09:40, Avri Altman <Avri.Altman@wdc.com> wrote:
>
> > In the SD spec v6.x the SD function extension registers for performance
> > enhancements were introduced. As a part of this an optional internal cache
> > on
> > the SD card can be used to improve performance.
> Just to verify that you are aware of that:
> In addition to the extension Registers that were defined in the physical core spec,
> there was a separate document that was released that suggest a common OS API's to those registers.
> It is called "SD specification part A5, SD Extensions API specification".

Thanks for the pointer!

I did have a very brief look at this. The conclusion I made is that
this is way over designed to enable support for features like cache
and poweroff notification. However, there may be other use cases that
could benefit from a user space library, along the lines of the SD
Extensions API, but I can't really tell.

Do you have an interest around this that you can share?

Thanks for reviewing!

Kind regards
Uffe