linux-kernel - Re: [PATCH V13 04/10] mmc: block: Add CQE support

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Message-ID: <09d283ab-ede5-3e1f-0233-39e222d35248@intel.com>
Date:   Thu, 9 Nov 2017 14:39:48 +0200
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Ulf Hansson <ulf.hansson@...aro.org>,
        linux-mmc <linux-mmc@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Bough Chen <haibo.chen@....com>,
        Alex Lemberg <alex.lemberg@...disk.com>,
        Mateusz Nowak <mateusz.nowak@...el.com>,
        Yuliy Izrailov <Yuliy.Izrailov@...disk.com>,
        Jaehoon Chung <jh80.chung@...sung.com>,
        Dong Aisheng <dongas86@...il.com>,
        Das Asutosh <asutoshd@...eaurora.org>,
        Zhangfei Gao <zhangfei.gao@...il.com>,
        Sahitya Tummala <stummala@...eaurora.org>,
        Harjani Ritesh <riteshh@...eaurora.org>,
        Venu Byravarasu <vbyravarasu@...dia.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH V13 04/10] mmc: block: Add CQE support

On 09/11/17 14:04, Linus Walleij wrote:
> On Wed, Nov 8, 2017 at 2:20 PM, Adrian Hunter <adrian.hunter@...el.com> wrote:
>> On 08/11/17 11:00, Linus Walleij wrote:
> 
>>> This and other bits gives me the feeling CQE is now actually ONLY
>>> working on the MQ path.
>>
>> I was not allowed to support non-mq.
> 
> Fair enough.
> 
>>> That is good. We only add new functionality on the MQ path,
>>> yay!
>>>
>>> But this fact (only abailable iff MQ==true) should at least be
>>> mentioned in the commit message I think?
>>
>> Why?  CQE is MQ only.
> 
> So if you read what I say, I think the commit message should
> say that CQE is MQ only so that people know that CQE is
> MQ only.

Alright

> 
>>> So why not ditch the old block layer or at least make MQ default?
>>
>> CQE is MQ only.
> 
> Yeah? So why keep it around for everything else?

Never said we should keep it around.  As soon as blk-mq is ready and tested,
delete it.

> 
>>> When you keep it like this people have to reconfigure
>>> their kernel to enable MQ before they see the benefits of MQ+CQE
>>> combined, I think that should rather be the default experience.
>>
>> Not at all.  I guess you are confusing the legacy mmc with CQE.  CQE is not
>> a layer on top of legacy mmc.  It is an alternative to legacy mmc.  CQE
>> does not sit on top of the legacy mmc blk-mq support.  You don't have to
>> enable legacy mmc blk-mq support to use CQE.
> 
> Now I am confused. I can't parse the last sentence. There is no
> such thing as legcay blk-mq?

Don't need non-CQE mmc blk-mq support for CQE support.