Re: [PATCH V9 13/15] mmc: block: Add CQE and blk-mq support

[Ulf Hansson]

On 5 October 2017 at 12:55, Bartlomiej Zolnierkiewicz
<b.zolnierkie@xxxxxxxxxxx> wrote:
> On Wednesday, October 04, 2017 11:48:27 AM Ulf Hansson wrote:
>> [...]
>>
>> >> MQ code that doesn't perform and therefore we cannot switch seamlessly
>> >> to MQ.
>> >
>> > I think that switching seamlessly to blk-mq in short/medium-term
>> > is not possible (SCSI tried and failed to do so). The changes to
>> > the old path are very complex and besides affecting performance
>> > they also affect error recovery handling (which needs to be tested
>> > properly before the switch).
>>
>> Agreed, and that's why I have queued up the new Kconfig option for
>> enabling the blkmq path from MMC.
>
> This seems premature - the new Kconfig option change for "mmc-mq" should
> belong to the patch adding "mmc-mq" support (otherwise it may just confuse
> users who enable it).

I agree!

However my plan was to move forward with the CMDQ series, but I
realize that I may need to drop the Kconfig patch, in case CMDQ don't
make it for 4.15.

Kind regards
Uffe