[PATCH 4/6] mmc: host: sdhci-esdhc-imx.c: correct the auto-tuning setting for sdio device

[haibo.chen at nxp.com]

From: Haibo Chen <haibo.chen at nxp.com>

USDHC contain auto tuning circuit, this circuit will work automatically after
the tuning procedurae, it can increase/decrease the delay cell according to
the outside environment change (like temperature).

Unfortunately, this auto tuning circuit can not handle the async sdio device
interrupt correctly. When sdio device use 4 data line, async sdio interrupt
will use DAT[1], if we enable auto tuning circuit check 4 data lines, include
the DAT[1], this circuit will detect this interrupt, take this as a data on
DAT[1], and adjust the delay cell wrongly.

This is the hardware design limitation, to avoid this, when sdio device enable
async interrupt, auto tuning circuit only check DAT[0] and CMD lines.

Signed-off-by: Haibo Chen <haibo.chen at nxp.com>
---
 drivers/mmc/host/sdhci-esdhc-imx.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index f18d169bc8ff..ab84c29777e5 100644
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -226,6 +226,7 @@ struct esdhc_platform_data {
 	unsigned int tuning_step;       /* The delay cell steps in tuning procedure */
 	unsigned int tuning_start_tap;	/* The start delay cell point in tuning procedure */
 	unsigned int strobe_dll_delay_target;	/* The delay cell for strobe pad (read clock) */
+	bool sdio_async_interrupt_enabled;	/* sdio device enable the async interrupt */
 };
 
 struct esdhc_soc_data {
@@ -416,6 +417,8 @@ static inline void esdhc_wait_for_card_clock_gate_off(struct sdhci_host *host)
 /* Enable the auto tuning circuit to check the CMD line and BUS line */
 static inline void usdhc_auto_tuning_mode_sel(struct sdhci_host *host)
 {
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct pltfm_imx_data *imx_data = sdhci_pltfm_priv(pltfm_host);
 	u32 buswidth, auto_tune_buswidth;
 
 	buswidth = USDHC_GET_BUSWIDTH(readl(host->ioaddr + SDHCI_HOST_CONTROL));
@@ -432,6 +435,18 @@ static inline void usdhc_auto_tuning_mode_sel(struct sdhci_host *host)
 		break;
 	}
 
+	/*
+	 * If sdio device use async interrupt, it will use DAT[1] to signal
+	 * the device's interrupt asynchronous when use 4 data lines.
+	 * Then hardware auto tuning circuit MUST NOT check the DAT[1] line,
+	 * otherwise auto tuning will be impacted by this async interrupt,
+	 * and change the delay cell incorrectly, which then cause data/cmd
+	 * errors.
+	 * This is the hardware auto tuning circuit limitation.
+	 */
+	if (imx_data->boarddata.sdio_async_interrupt_enabled)
+		auto_tune_buswidth = ESDHC_VEND_SPEC2_AUTO_TUNE_1BIT_EN;
+
 	esdhc_clrset_le(host, ESDHC_VEND_SPEC2_AUTO_TUNE_MODE_MASK,
 			auto_tune_buswidth | ESDHC_VEND_SPEC2_AUTO_TUNE_CMD_EN,
 			ESDHC_VEND_SPEC2);
@@ -1531,6 +1546,9 @@ sdhci_esdhc_imx_probe_dt(struct platform_device *pdev,
 	if (of_property_read_u32(np, "fsl,delay-line", &boarddata->delay_line))
 		boarddata->delay_line = 0;
 
+	if (of_property_read_bool(np, "fsl,sdio-async-interrupt-enabled"))
+		boarddata->sdio_async_interrupt_enabled = true;
+
 	mmc_of_parse_voltage(host->mmc, &host->ocr_mask);
 
 	if (esdhc_is_usdhc(imx_data) && !IS_ERR(imx_data->pinctrl)) {
-- 
2.17.1