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Subject[PATCH] mmc: mxs: fix card detection function for broken card detect
Date
Return -ENOSYS in get_cd if broken-cd is specified in the device tree.

Commit a91fe279ae75 (mmc: mxs: use standard flag for broken card
detection) sets MMC_CAP_NEEDS_POLL when broken-cd is specified. This
driver sets this flag unconditionally as it does not support a card
detect interrupt. Instead, broken-cd means that there is no card detect
signal connected.

The mmc core checks the get_cd function return value to determine if a
card is present. Only for a non-zero return value it will attempt to
initialize the card. So retuning -ENOSYS will allow the card to be
initialized.
For comparison, mmc_gpio_get_cd in slot-gpio.c also returns -ENOSYS if
the card detect GPIO is not valid.

Signed-off-by: Daniel Willmann <daniel@totalueberwachung.de>
---
This might be relevant for stable kernels. The patch was tested with 3.14.1 on
olinuxino nano.

drivers/mmc/host/mxs-mmc.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
index 073e871a0fc8..babfea03ba8a 100644
--- a/drivers/mmc/host/mxs-mmc.c
+++ b/drivers/mmc/host/mxs-mmc.c
@@ -70,6 +70,7 @@ struct mxs_mmc_host {
unsigned char bus_width;
spinlock_t lock;
int sdio_irq_en;
+ bool broken_cd;
};

static int mxs_mmc_get_cd(struct mmc_host *mmc)
@@ -78,6 +79,9 @@ static int mxs_mmc_get_cd(struct mmc_host *mmc)
struct mxs_ssp *ssp = &host->ssp;
int present, ret;

+ if (host->broken_cd)
+ return -ENOSYS;
+
ret = mmc_gpio_get_cd(mmc);
if (ret >= 0)
return ret;
@@ -568,6 +572,7 @@ static int mxs_mmc_probe(struct platform_device *pdev)
{
const struct of_device_id *of_id =
of_match_device(mxs_mmc_dt_ids, &pdev->dev);
+ struct device_node *np = pdev->dev.of_node;
struct mxs_mmc_host *host;
struct mmc_host *mmc;
struct resource *iores;
@@ -634,6 +639,8 @@ static int mxs_mmc_probe(struct platform_device *pdev)
mmc->caps = MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED |
MMC_CAP_SDIO_IRQ | MMC_CAP_NEEDS_POLL;

+ host->broken_cd = of_property_read_bool(np, "broken-cd");
+
mmc->f_min = 400000;
mmc->f_max = 288000000;

--
1.8.4.2


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