[RFC PATCH 2/2] mmc: dw_mmc: check card present before starting request

Shawn Lin shawn.lin at rock-chips.com
Wed May 25 20:08:11 PDT 2016

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 at 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)
+	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

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