On 20 March 2013 10:04, Huang Changming-R66093 <r66093@xxxxxxxxxxxxx> wrote: > They have different function, Kevin's patch is for slowly removed, it can't resolve the performance issue. Actually I am not sure what your patch is trying to solve. Kevin's patch makes sense. Can you elaborate a bit on what performance issues that needs to be considered during card removal? > First, we should use get_cd to get the card status, if it is not supported, then use the alive to send CMD13. > For the driver that supports get_cd, the system performance can upgrade. > Maybe Kevin can base on this patch. > > Best Regards > Jerry Huang > > >> -----Original Message----- >> From: Ulf Hansson [mailto:ulf.hansson@xxxxxxxxxx] >> Sent: Wednesday, March 20, 2013 4:43 PM >> To: Huang Changming-R66093 >> Cc: linux-mmc@xxxxxxxxxxxxxxx; Chris Ball >> Subject: Re: [PATCH 1/3i v6] MMC/SD: Add callback function to detect card >> >> On 20 March 2013 06:41, <Chang-Ming.Huang@xxxxxxxxxxxxx> wrote: >> > From: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx> >> > >> > 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. >> > From the performance test on Freescale's board (such as Iozone for >> > SD), the performance will degrade about 4~6%. >> > >> > There is one another way to get this information, which is to read the >> > register PRSSTAT and check the bit CDPL or CINS. >> > If the card is present, these two bit will set to one. >> > Therefore, add callback function get_cd() to check whether the card >> > has been inserted/removed when the driver supports this feature. >> > If the card is present, 0 will return, if the card is absent, 1 will >> return. >> > If the controller will not support this feature, -ENOSYS will return. >> > >> > Signed-off-by: Jerry Huang <Chang-Ming.Huang@xxxxxxxxxxxxx> >> > Reviewed-by: Johan Rudholm <johan.rudholm@xxxxxxxxxxxxxx> >> > Reviewed-by: Anton Vorontsov <cbouatmailru@xxxxxxxxx> >> > CC: Chris Ball <cjb@xxxxxxxxxx> >> > --- >> > 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 changes for v5: >> > - reviewed by Anton and Johan, add the reviewed-by. >> > changes for v6: >> > - add more comment. >> > >> > drivers/mmc/core/core.c | 16 ++++++++++++++-- >> > 1 file changed, 14 insertions(+), 2 deletions(-) >> > >> > diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index >> > 08a3cf2..e225deb 100644 >> > --- a/drivers/mmc/core/core.c >> > +++ b/drivers/mmc/core/core.c >> > @@ -2280,7 +2280,7 @@ static int mmc_rescan_try_freq(struct mmc_host >> > *host, unsigned freq) >> > >> > 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; >> > @@ -2288,7 +2288,19 @@ 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); >> > + /* First, try host-controller's card detect callback */ >> > + if (host->ops->get_cd) { >> > + ret = host->ops->get_cd(host); >> > + /* >> > + * The return value from get_cd: 1 for present, 0 for >> absent, >> > + * we need to convert it to: 1 for absent, 0 for >> present. >> > + */ >> > + if (ret >= 0) >> > + ret = !ret; >> > + } >> > + /* If failed, back to the bus_ops alive() callback */ >> > + 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)); >> >> I guess this already has been fixed by Kevin's patch below. >> >> http://article.gmane.org/gmane.linux.kernel.mmc/19481 >> >> > -- >> > 1.7.9.5 >> > >> > >> > -- >> > To unsubscribe from this list: send the line "unsubscribe linux-mmc" in >> > the body of a message to majordomo@xxxxxxxxxxxxxxx >> > More majordomo info at http://vger.kernel.org/majordomo-info.html >> >> Kind regards >> Ulf Hansson > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
