From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jaehoon Chung Subject: Re: [PATCH v2 2/2] mmc: dw_mmc: check card present before starting request Date: Mon, 30 May 2016 08:18:48 +0900 Message-ID: <574B78D8.50903@samsung.com> References: <1464331025-16275-1-git-send-email-shawn.lin@rock-chips.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-reply-to: <1464331025-16275-1-git-send-email-shawn.lin@rock-chips.com> Sender: linux-kernel-owner@vger.kernel.org To: Shawn Lin , Ulf Hansson Cc: linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Doug Anderson , linux-rockchip@lists.infradead.org List-Id: linux-rockchip.vger.kernel.org Hi Shawn, On 05/27/2016 03:37 PM, Shawn Lin wrote: > The main reason to add this check is to avoid unnecessary > mmc_request like the on-going cmd and the corresponding sbc > if the card is removed. Although we have already checked 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 Applied on my repository. Thanks! Best Regards, Jaehoon Chung > > --- > > Changes in v2: > - hold lock before dw_mci_queue_request > > drivers/mmc/host/dw_mmc.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c > index cb30e91..2b4b3df 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) > @@ -1253,15 +1254,15 @@ static void dw_mci_request(struct mmc_host *mmc, struct mmc_request *mrq) > * atomic, otherwise the card could be removed in between and the > * request wouldn't fail until another card was inserted. > */ > - spin_lock_bh(&host->lock); > > - if (!test_bit(DW_MMC_CARD_PRESENT, &slot->flags)) { > - spin_unlock_bh(&host->lock); > + if (!dw_mci_get_cd(mmc)) { > mrq->cmd->error = -ENOMEDIUM; > mmc_request_done(mmc, mrq); > return; > } > > + spin_lock_bh(&host->lock); > + > dw_mci_queue_request(host, slot, mrq); > > spin_unlock_bh(&host->lock); >