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From:   =?Windows-1252?Q?Christian_L=F6hle?= <CLoehle@hyperstone.com>
To:     Adrian Hunter <adrian.hunter@intel.com>,
        Avri Altman <Avri.Altman@wdc.com>,
        Michael Wu <michael@allwinnertech.com>,
        "ulf.hansson@linaro.org" <ulf.hansson@linaro.org>,
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CC:     "linux-mmc@vger.kernel.org" <linux-mmc@vger.kernel.org>,
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        allwinner-opensource-support 
        <allwinner-opensource-support@allwinnertech.com>
Subject: Re: [PATCH] mmc: block: enable cache-flushing when mmc cache is on
Thread-Topic: [PATCH] mmc: block: enable cache-flushing when mmc cache is on
Thread-Index: AQHYNcu3WGf4zsUDOUapUgyqsaCvc6y+ZEOAgAAo/4CAAASLgIADKXiAgAAU4oCAAAVPgIAARzTm
Date:   Wed, 16 Mar 2022 14:46:02 +0000
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>So we are not going to let the block layer know about SD cache?
>Or is it a separate change?

I have some code for this laying around, but as it requires reading, parsing and writing Function Registers,
in particular PEH, it's a lot of boilerplate code to get the functionality, but I'll clean it up and send a patch in the coming weeks.


From: Adrian Hunter <adrian.hunter@intel.com>
Sent: Wednesday, March 16, 2022 12:28 PM
To: Avri Altman; Michael Wu; ulf.hansson@linaro.org; beanhuo@micron.com; porzio@gmail.com
Cc: linux-mmc@vger.kernel.org; linux-kernel@vger.kernel.org; allwinner-opensource-support
Subject: Re: [PATCH] mmc: block: enable cache-flushing when mmc cache is on
?   
On 16.3.2022 13.09, Avri Altman wrote:
>> Hi Avril & Adrian,
>> Thanks for your efforts. Could we have an agreement now --
>>
>> 1. enabling-cache and cmd23/reliable-write should be independent;
>>
>> Here's what I found in the spec JESD84-B51:
>>? > 6.6.31 Cache
>>? > Caching of data shall apply only for the single block
>>? > read/write(CMD17/24), pre-defined multiple block
>>? > read/write(CMD23+CMD18/25) and open ended multiple block
>>? > read/write(CMD18/25+CMD12) commands and excludes any other access
>>? > e.g., to the register space(e.g., CMD6).
>> Which means with CMD18/25+CMD12 (without using CMD23), the cache can
>> also be enabled. Maybe this could be an evidence of the independence
>> between enabling-cache and cmd23/reliable-write?
> Acked-by: Avri Altman <avri.altman@wdc.com>
> 
> Thanks,
> Avri
> 
>>
>> 2. We don't consider supporting SD in this change.
>>
>>? > On 14/03/2022 19:10, Avri Altman wrote:
>>? >> Here is what our SD system guys wrote:
>>? >> " In SD we don?t support reliable write and this eMMC driver may not
>>? >>??? be utilizing the cache feature we added in SD5.0.
>>? >>?? The method of cache flush is different between SD and eMMC."
>>? >>
>>? >> So adding SD seems to be out of scope of this change.
>>
>> Is there anything else I can do about this patch? Thanks again.

So we are not going to let the block layer know about SD cache?
Or is it a separate change?
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