Re: [RFC PATCH 0/4] Introduce new caps to improve the card's init sequence

[Shawn Lin]

å 2016/6/22 20:37, Ulf Hansson åé:
> On 8 June 2016 at 10:19, Shawn Lin <shawn.lin@xxxxxxxxxxxxxx> wrote:
> > Hi all,
> >
> > This patchset is gonna improve the card's init sequence
> > by exposing some caps to DT.
> >
> > The basic idea is to skip sending specific init cmd inspired
> > by Carlo Caione's commit[0].
> >
> > To make it possible, I firstly expose Carlo's MMC_CAP2_NO_SDIO
> > to DT and extend two new caps for similar usage of sd and mmc.
> > We probably need it because for most of the boards, each of the
> > slots should have a specific function when designed. It's impossible
> > for one slot which can either to be used as eMMC or a SD card for a
> > given board. The same for SDIO case.
> >
> > We could have two ways to improve it
> > A) Skip sending specific commands if knowing we don't support
> > the specific card type.
> > B) Allow sending specific commands if knowing we do support
> > the specific card type.
> >
> > A) and B) shouldn't have difference, but I take A) as the final
> > one as it looks more consistent with Carlo's way, which does not
> > seem to break anything as possible.
> >
> > The only roadblock for this patchset to be landed should be the
> > improvement we gain from it. Theoretically sdio-card doesn't get
> > improvment as it's already in the first place to be attached.
> > But considering the sd and (e)MMC case, we should gain more benifit
> > from it.
> >
> > From the test, we can save nearly 2ms for attaching emmc against the
> > original 8ms. And we gain more than 30us improvement for sd card for
> > each insert.
> >
> > [0]: http://permalink.gmane.org/gmane.linux.kernel.mmc/34774
> >
> >
> >
> > Shawn Lin (4):
> >   Documentation: mmc: add description for new caps
> >   mmc: core: expose MMC_CAP2_NO_SDIO to dt-binding
> >   mmc: core: add cap-no-sd and cap-no-mmc properties
> >   mmc: core: improve initialization flow
>
> I would prefer that you restructure this series a bit.

I will do it and I think Doug was asking we to drop the "cap-"
prefix which I think need to be clarified before sending
non-RFC one. :)

> Start by adding each new MMC_CAP2* separately and without involving
> the DT parsing.
>
> Make the DT documentation patch come after the above, and add a new
> separate patch which exposes the caps to device tree.
>
> In that way, I can pick up the non DT parts and wait for Rob's
> ack/nack of the DT bindings.
>
> Kind regards
> Uffe
>
> >  Documentation/devicetree/bindings/mmc/mmc.txt |  3 +++
> >  drivers/mmc/core/core.c                       | 10 +++++-----
> >  drivers/mmc/core/host.c                       |  6 ++++++
> >  include/linux/mmc/host.h                      |  2 ++
> >  4 files changed, 16 insertions(+), 5 deletions(-)
> >
> > --
> > 2.3.7
> >
> >
> > --
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--
Best Regards
Shawn Lin