> -----Original Message-----
> From: Aaron Lu [mailto:aaron...@amd.com]
> Sent: Friday, January 13, 2012 11:27 AM
> To: Huang Changming-R66093
> Cc: linux-mmc@vger.kernel.org; Chris Ball
> Subject: Re: [PATCH 2/4 v4] MMC/SD: Add callback function to detect card
>
> Hi,
>
> On Fri, Jan 13, 2012 at 02:25:11AM +0000, Huang Changming-R66093 wrote:
> > Hi, Chris,
> > Could you have any comment about this patch?
> > Can it go into 3.3 or 3.4?
> >
> > Thanks
> > Jerry Huang
> > > -----Original Message-----
> > > From: Huang Changming-R66093
> > > Sent: Tuesday, December 27, 2011 4:01 PM
> > > To: linux-mmc@vger.kernel.org
> > > Cc: Huang Changming-R66093; Chris Ball
> > > Subject: [PATCH 2/4 v4] MMC/SD: Add callback function to detect card
> > >
> > > From: Jerry Huang <chang-ming.hu...@freescale.com>
> > >
> > > In order to check whether the card has been removed, the function
> > > mmc_send_status() will send command CMD13 to card and ask the card
> > > to send its status register to sdhc driver, which will generate many
> > > interrupts repeatedly and make the system performance bad.
>
> For sd hosts, this should only happen for hosts which have
> SDHCI_QUIRK_BROKEN_CARD_DETECTION set.
Yes, but which will impact the performance.
> > >
> > > Therefore, add callback function get_cd() to check whether the card
> > > has been removed when the driver has this callback function.
>
> I don't quite get the meaning of cd, what does get_cd suppose to mean?
This get_cd callback is implement in the special platform, because some SOC
don't support this feature
> > >
> > > If the card is present, 1 will return, if the card is absent, 0 will
> > > return.
> > > If the controller will not support this feature, -ENOSYS will return.
>
> What about get_present, return 0 for present, and return error code
> otherwise like the alive function does.
The hook to detect card is get_cd in the kernel, don't need the new.
> > >
> > > Signed-off-by: Jerry Huang <chang-ming.hu...@freescale.com>
> > > CC: Chris Ball <c...@laptop.org>
> > > ---
> > > changes for v2:
> > > - when controller don't support get_cd, return -ENOSYS
> > > - add the CC
> > > changes for v3:
> > > - enalbe the controller clock in platform, instead of core
> > > changes for v4:
> > > - move the detect code to core.c according to the new structure
> > >
> > > drivers/mmc/core/core.c | 10 ++++++++--
> > > 1 files changed, 8 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index
> > > 6db6621..d570c72 100644
> > > --- a/drivers/mmc/core/core.c
> > > +++ b/drivers/mmc/core/core.c
> > > @@ -2060,7 +2060,7 @@ static int mmc_rescan_try_freq(struct mmc_host
> > > *host, unsigned freq)
> > >
>
> snip
> > > int _mmc_detect_card_removed(struct mmc_host *host) {
> > > - int ret;
> > > + int ret = -ENOSYS;
> > >
> > > if ((host->caps & MMC_CAP_NONREMOVABLE) || !host->bus_ops->alive)
> > > return 0;
> > > @@ -2068,7 +2068,13 @@ int _mmc_detect_card_removed(struct mmc_host
> *host)
> > > if (!host->card || mmc_card_removed(host->card))
> > > return 1;
> > >
> > > - ret = host->bus_ops->alive(host);
> > > + if (host->ops->get_cd) {
> > > + ret = host->ops->get_cd(host);
> > > + if (ret >= 0)
> > > + ret = !ret;
> > > + }
> > > + if (ret < 0)
> > > + ret = host->bus_ops->alive(host);
> > > if (ret) {
> > > mmc_card_set_removed(host->card);
> > > pr_debug("%s: card remove detected\n", mmc_hostname(host));
> > > --
> > > 1.7.5.4
>
> And the code can be changed to something like:
> if (host->ops->get_present)
> ret = host->ops->get_present(host);
> else
> ret = host->bus_ops->alive(host);
> if (ret) {
> mmc_card_set_removed(host->card);
> pr_debug("%s: card remove detected\n", mmc_hostname(host));
> }
>
>
> Does this make sense?
No.
Because the get_cd is the hook to detect card in mmc_host_ops structure in
include/linux/mmc/host.h.
We don't need to add new.
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