> -----Original Message----- > From: linux-mmc-owner@xxxxxxxxxxxxxxx [mailto:linux-mmc-owner@xxxxxxxxxxxxxxx] On Behalf Of Huang Changming-R66093 > Sent: Thursday, March 21, 2013 11:29 AM > To: Ulf Hansson > Cc: linux-mmc@xxxxxxxxxxxxxxx; Chris Ball > Subject: RE: [PATCH 1/3i v6] MMC/SD: Add callback function to detect card > > In the current codes, SDHCI use the CMD13 to detect the card status. So there are many interrupt for this command, regardless of the card is absent or present. > When the card is removed, these interrupts are still generated, which will cause the performance degrade (such as Iozone for SATA I/O pressure test). > > And in the current SD/MMC stack, there is one callback "get_cd" which is used on some platforms. > So I introduce it to SDHCI, if the driver support this callback, we first use it, instead of CMD13. > Jerry, Function _mmc_detect_card_removed should only be called when card insert/removal or i/o error occur unless POLLING is used(called once per second). So it should _not_ impact performance much. POLLING is poor for performance, why not change to slot-gpio if host is broken for card detect. I think function _mmc_detect_card_removed aim to verify whether card still exist by communicate with card. Thanks Kevin > Best Regards > Jerry Huang > > >> -----Original Message----- >> From: Ulf Hansson [mailto:ulf.hansson@xxxxxxxxxx] >> Sent: Wednesday, March 20, 2013 5:29 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 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 -- 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
