From: Magnus Damm <damm+renesas@xxxxxxxxxxxxx>
This patch adds comments to describe the various ways card detection
may be implemented and when polling is needed. Also a fix is included
to prevent the MMC SPI driver from polling when a CD GPIO that supports
interrupts is specified using the gpios DT property (case 1).
Without this patch the DT node below results in the following output:
spi_gpio: spi-gpio { /* SD2 @ CN12 */
compatible = "spi-gpio";
#address-cells = <1>;
#size-cells = <0>;
gpio-sck = <&gpio6 16 GPIO_ACTIVE_HIGH>;
gpio-mosi = <&gpio6 17 GPIO_ACTIVE_HIGH>;
gpio-miso = <&gpio6 18 GPIO_ACTIVE_HIGH>;
num-chipselects = <1>;
cs-gpios = <&gpio6 21 GPIO_ACTIVE_LOW>;
status = "okay";
spi@0 {
compatible = "mmc-spi-slot";
reg = <0>;
voltage-ranges = <3200 3400>;
spi-max-frequency = <25000000>;
gpios = <&gpio6 22 GPIO_ACTIVE_LOW>; /* CD */
};
};
# dmesg | grep mmc
mmc_spi spi32766.0: SD/MMC host mmc0, no WP, no poweroff, cd polling
mmc0: host does not support reading read-only switch, assuming write-enable
mmc0: new SDHC card on SPI
mmcblk0: mmc0:0000 SU04G 3.69 GiB
mmcblk0: p1
With this patch applied the "cd polling" portion above disappears.
Signed-off-by: Magnus Damm <damm+renesas@xxxxxxxxxxxxx>
---
Developed on top of renesas-drivers-2016-02-09-v4.5-rc3 which
simply put is v4.5-rc3 + selected linux-next trees.
drivers/mmc/host/mmc_spi.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
--- 0001/drivers/mmc/host/mmc_spi.c
+++ work/drivers/mmc/host/mmc_spi.c 2016-02-16 12:47:47.900513000 +0900
@@ -1437,11 +1437,25 @@ static int mmc_spi_probe(struct spi_devi
if (status != 0)
goto fail_add_host;
+ /* Card detection in case of DT is supported in several ways:
+ * 1) GPIO with interrupt support using "gpios" DT property.
+ * 2) GPIO without interrupt support using "gpios" DT property.
+ * 3) Interrupt only using "interrupt-parent/interrupts" DT properties.
+ * 4) Both "gpios" and "interrupt-parent/interrupts" DT properties.
+ * 5) Nothing specified.
+ * For case 2 and 5 above polling is required.
+ */
if (host->pdata && host->pdata->flags & MMC_SPI_USE_CD_GPIO) {
status = mmc_gpio_request_cd(mmc, host->pdata->cd_gpio,
host->pdata->cd_debounce);
if (status != 0)
goto fail_add_host;
+
+ /* The platform has a CD GPIO signal that may support
+ * interrupts, so let mmc_gpiod_request_cd_irq() decide
+ * if polling is needed or not.
+ */
+ mmc->caps &= ~MMC_CAP_NEEDS_POLL;
mmc_gpiod_request_cd_irq(mmc);
}
--
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