From: Haibo Chen <haibo.chen@xxxxxxx>
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@xxxxxxx>
---
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
