Re: [PATCH V2 0/2] mmc: Minimize resume time for sd/mmc

[Ulf Hansson <ulf.hansson@stericsson.com>]

Hi Chris,

I have received some great comments some Vitaly Wool around the patch 2
"mmc: Minimize resume-time by deferring resume".

It would be interesting to hear if you or someone else has any thinking 
around these patches. Vitaly were mainly thinking of a pm_qos approach, 
which still is a bit unclear to me how to implement.

Any suggestion would be great! :-)

Regarding patch 1:
mmc: block: Remove use of mmc_blk_set_blksize
This patch could be discussed separately without patch 2. Do you want me 
to push this patch on it's own?


BR
Ulf Hansson



Ulf HANSSON wrote:
> Typically an sd/mmc card takes around 200 - 1100 ms to
> initialize when the power to the card has been cut, which
> is what happens during a suspend/resume sequence.
> 
> All device's resume time adds up to the total kernel resume
> time. Some use cases requires the kernel to be resumed fast,
> to be able to meet deadlines. One use case example is WLAN
> SOFT_AP, but there are certainly more.
> 
> This patch serie deferres the resume for mmc/sd cards into
> a delayed work to be able to respond quickly on the suspend
> request. Earlier the blkdev were issuing a set_blksize as a
> part of the blkdev resume, which right now is removed since
> it is not needed. In future, if other block sizes than 512
> bytes is used, this needs to be re-implemented in a different
> manner.
> 
> A deferred resume feature has been discussed on the mmc-list
> previously but did not end up in a final patch/solution.
> 
> Ulf Hansson (2):
>   mmc: block: Remove use of mmc_blk_set_blksize
>   mmc: Minimize resume-time by deferring resume
> 
>  drivers/mmc/card/block.c |   35 +++++++++--------------------------
>  drivers/mmc/core/core.c  |   36 +++++++++++++++++++++++++++++++++++-
>  drivers/mmc/core/core.h  |    1 +
>  drivers/mmc/core/host.c  |    1 +
>  include/linux/mmc/host.h |   16 ++++++++++++++++
>  5 files changed, 62 insertions(+), 27 deletions(-)
>