RE: [PATCH v4 2/2] mmc: core: Support packed command for eMMC4.5 device

[Seungwon Jeon <tgih.jun@samsung.com>]

Maya Erez <merez@codeaurora.org> wrote:
> > @@ -1262,21 +1608,32 @@ static int mmc_blk_issue_rw_rq(struct mmc_queue
> > *mq, struct request *rqc)
> >  	int ret = 1, disable_multi = 0, retry = 0, type;
> >  	enum mmc_blk_status status;
> >  	struct mmc_queue_req *mq_rq;
> > -	struct request *req;
> > +	struct request *req, *prq;
> >  	struct mmc_async_req *areq;
> > +	u8 reqs = 0;
> >
> >  	if (!rqc && !mq->mqrq_prev->req)
> >  		return 0;
> >
> > +	if (rqc)
> > +		reqs = mmc_blk_prep_packed_list(mq, rqc);
> > +
> >  	do {
> >  		if (rqc) {
> > -			mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
> > +			if (reqs >= card->host->packed_min)
> In case host->packed_min will be set to a value bigger than 2 you will
> loose all the requests that were added to the packed list. If you want to
> support dynamic number of min packed requests you need to move the packed
> list preparation to queue.c where you can issue the fetched requests one
> after another, when (reqs < card->host->packed_min).

That's a good point.
The requests added to the packed list will be remained
if current number of packed request is less than packed_min.
In such a case, requests should be put back to request_queue from packed list.
I think it's a additional and unnecessary work due to packed_min.
It's not interesting. So I want to revert this regulation of packed_min.

And we have discussed the location of mmc_blk_prep_packed_list(block.c or queue.c) several times.
Packed command is valid only if request type is read/write,
so it may be a good location to decide in mmc_blk_issue_rw_rq in block.c.
I guess you want this function to be located in mmc_queue_thread in queue.c, right?
Is it advantageous? Could you explain for this?

Thanks,
Seungwon Jeon
> > +				mmc_blk_packed_hdr_wrq_prep(mq->mqrq_cur, card, mq, reqs);
> > +			else
> > +				mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
> 
> Thanks,
> Maya Erez
> Consultant for Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
> 
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