Hi, If use the non-removable (eMMC), driver does not send the CMD13. But the most case is removable (SD, SDHC or MMC), driver will send CMD13 to get the card status. I don't know if your driver sdhci-s3c.c is non-removable. But for removable card, this degrade will be observed when pressure test (fio or Iozone). Best Regards Jerry Huang > -----Original Message----- > From: Jaehoon Chung [mailto:jh80.chung@xxxxxxxxxxx] > Sent: Friday, March 22, 2013 1:44 PM > To: Huang Changming-R66093 > Cc: Ulf Hansson; linux-mmc@xxxxxxxxxxxxxxx; Chris Ball > Subject: Re: [PATCH 1/3i v6] MMC/SD: Add callback function to detect card > > Hi, > > As my understanding, You means that controller is sending CMD13 to detect > the card at every time. > Right? > If card is nonremovable (eMMC), need not to send the CMD13 to card detect > and actually didn't send the command. > Then how do you implement the code in get_cd? > > Actually, i didn't see the any performance degrade with sdhci-s3c.c > > Best Regards, > Jaehoon Chung > > On 03/21/2013 12:28 PM, Huang Changming-R66093 wrote: > > 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. > > > > 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
