| Message ID | 1464232091-24882-1-git-send-email-shawn.lin@rock-chips.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Shawn, On 05/26/2016 12:08 PM, Shawn Lin wrote: > The main reason to add this check is to avoid unnecessary > mmc_request if the card is removed. Although we have already > check this in dw_mci_handle_cd for runtime usage of sd card and > dw_mci_init_slot for noremovable devices, but there is a timing > gap before it really calls dw_mci_get_cd as mmc_detect_change needs > some delay here. What's unnecessary mmc_request? > > Another gain here is that we could save some checkings of card status > after sd card been removed. > > Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> > --- > > drivers/mmc/host/dw_mmc.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index cb30e91..2940d24 100644 > --- a/drivers/mmc/host/dw_mmc.c > +++ b/drivers/mmc/host/dw_mmc.c > @@ -105,6 +105,7 @@ struct idmac_desc { > static bool dw_mci_reset(struct dw_mci *host); > static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset); > static int dw_mci_card_busy(struct mmc_host *mmc); > +static int dw_mci_get_cd(struct mmc_host *mmc); > > #if defined(CONFIG_DEBUG_FS) > static int dw_mci_req_show(struct seq_file *s, void *v) > @@ -1248,6 +1249,8 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq) > > WARN_ON(slot->mrq); > > + dw_mci_get_cd(mmc); > + If my understanding is right, it can be replaced if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) to if (!dw_mci_get_cd(mmc)) Best Regards, Jaehoon Chung > /* > * The check for card presence and queueing of the request must be > * atomic, otherwise the card could be removed in between and the > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Jaehoon, On 2016/5/27 8:53, Jaehoon Chung wrote: > Hi Shawn, > > On 05/26/2016 12:08 PM, Shawn Lin wrote: >> The main reason to add this check is to avoid unnecessary >> mmc_request if the card is removed. Although we have already >> check this in dw_mci_handle_cd for runtime usage of sd card and >> dw_mci_init_slot for noremovable devices, but there is a timing >> gap before it really calls dw_mci_get_cd as mmc_detect_change needs >> some delay here. > > What's unnecessary mmc_request? the on-going read/write/ and the corresponding sbc like cmd13, etc. > >> >> Another gain here is that we could save some checkings of card status >> after sd card been removed. >> >> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> >> --- >> >> drivers/mmc/host/dw_mmc.c | 3 +++ >> 1 file changed, 3 insertions(+) >> >> diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c >> index cb30e91..2940d24 100644 >> --- a/drivers/mmc/host/dw_mmc.c >> +++ b/drivers/mmc/host/dw_mmc.c >> @@ -105,6 +105,7 @@ struct idmac_desc { >> static bool dw_mci_reset(struct dw_mci *host); >> static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset); >> static int dw_mci_card_busy(struct mmc_host *mmc); >> +static int dw_mci_get_cd(struct mmc_host *mmc); >> >> #if defined(CONFIG_DEBUG_FS) >> static int dw_mci_req_show(struct seq_file *s, void *v) >> @@ -1248,6 +1249,8 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq) >> >> WARN_ON(slot->mrq); >> >> + dw_mci_get_cd(mmc); >> + > > If my understanding is right, it can be replaced > > if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) > > to > > if (!dw_mci_get_cd(mmc)) yeah~ It looks better. > > > Best Regards, > Jaehoon Chung > > > >> /* >> * The check for card presence and queueing of the request must be >> * atomic, otherwise the card could be removed in between and the >> > > > >
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c index cb30e91..2940d24 100644 --- a/drivers/mmc/host/dw_mmc.c +++ b/drivers/mmc/host/dw_mmc.c @@ -105,6 +105,7 @@ struct idmac_desc { static bool dw_mci_reset(struct dw_mci *host); static bool dw_mci_ctrl_reset(struct dw_mci *host, u32 reset); static int dw_mci_card_busy(struct mmc_host *mmc); +static int dw_mci_get_cd(struct mmc_host *mmc); #if defined(CONFIG_DEBUG_FS) static int dw_mci_req_show(struct seq_file *s, void *v) @@ -1248,6 +1249,8 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq) WARN_ON(slot->mrq); + dw_mci_get_cd(mmc); + /* * The check for card presence and queueing of the request must be * atomic, otherwise the card could be removed in between and the
The main reason to add this check is to avoid unnecessary mmc_request if the card is removed. Although we have already check this in dw_mci_handle_cd for runtime usage of sd card and dw_mci_init_slot for noremovable devices, but there is a timing gap before it really calls dw_mci_get_cd as mmc_detect_change needs some delay here. Another gain here is that we could save some checkings of card status after sd card been removed. Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> --- drivers/mmc/host/dw_mmc.c | 3 +++ 1 file changed, 3 insertions(+)