From mboxrd@z Thu Jan  1 00:00:00 1970
From: Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH RFC] scsi: ufs: Disable blk-mq for now
Date: Thu, 13 Sep 2018 15:15:39 +0300
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 <20180913120459.GA4965@ming.t460p>
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To: Ming Lei <ming.lei@redhat.com>
Cc: "Martin K . Petersen" <martin.petersen@oracle.com>, "James E . J . Bottomley" <jejb@linux.vnet.ibm.com>, Jens Axboe <axboe@kernel.dk>, Christoph Hellwig <hch@lst.de>, Johannes Thumshirn <jthumshirn@suse.de>, Bart Van Assche <Bart.VanAssche@wdc.com>, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Stanislav Nijnikov <stanislav.nijnikov@wdc.com>, Evan Green <evgreen@chromium.org>, Vinayak Holikatti <vinholikatti@gmail.com>, Janek Kotas <jank@cadence.com>, Vivek Gautam <vivek.gautam@codeaurora.org>, Asutosh Das <asutoshd@codeaurora.org>, Subhash Jadavani <subhashj@codeaurora.org>, Sayali Lokhande <sayalil@codeaurora.org>, Li Wei <liwei213@huawei.com>, Bjorn Andersson <bjorn.andersson@linaro.org>, Jaegeuk Kim <jaegeuk@kernel.org>
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On 13/09/18 15:05, Ming Lei wrote:
> On Thu, Sep 13, 2018 at 02:28:48PM +0300, Adrian Hunter wrote:
>> blk-mq does not support runtime pm, so disable blk-mq support for now.
> 
> So could you describe a bit what the issue you are trying to fix?

UFS is a low-power solution, so we must be able to runtime suspend.

> 
> This is host level runtime PM you are trying to address, and if blk-mq
> runtime isn't enabled, I guess the host won't be runtime suspended at all
> because some of its descendant are always active.
> 
> So seems we need to do nothing for preventing the host controller from
> entering runtime suspend.

We don't want to prevent the host controller from runtime suspending, quite
the opposite.