mmc: dw_mmc: Do not wait for DTO in case of error

When running the ARTPEC-8 DWMMC IP version, and a data error interrupt
comes during a data read transfer, there is no guarantee for the data
transfer over interrupt (DTO) to come within the specified data timeout.
This case is handled by the dto_timer handler which will complete the
request with the comment:

 /*
  * If DTO interrupt does NOT come in sending data state,
  * we should notify the driver to terminate current transfer
  * and report a data timeout to the core.
  */

But since the ARTPEC-8 DWMMC IP version, supports an extended TMOUT
register which allows longer timeouts than the non ARTPEC-8 version
does, waiting for the dto_timer to complete the request in error cases
may cause the request to take significantly longer time than necessary.
This is specifically true for the failing steps during tuning of a
device.

Fix this by completing the request when the error interrupt comes. Since
this fix is specific for the ARTPEC-8, a quirk is added.

Signed-off-by: Mårten Lindahl <marten.lindahl@axis.com>
Link: https://lore.kernel.org/r/20211220113026.21129-5-marten.lindahl@axis.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/dw_mmc-exynos.c

@@ -127,6 +127,11 @@ static int dw_mci_exynos_priv_init(struct dw_mci *host)
 				DQS_CTRL_GET_RD_DELAY(priv->saved_strobe_ctrl);
 	}
 
+	if (priv->ctrl_type == DW_MCI_TYPE_ARTPEC8) {
+		/* Quirk needed for the ARTPEC-8 SoC */
+		host->quirks |= DW_MMC_QUIRK_EXTENDED_TMOUT;
+	}
+
 	host->bus_hz /= (priv->ciu_div + 1);
 
 	return 0;

drivers/mmc/host/dw_mmc.c

@@ -2762,11 +2762,20 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
 		if (pending & DW_MCI_DATA_ERROR_FLAGS) {
 			spin_lock(&host->irq_lock);
 
+			if (host->quirks & DW_MMC_QUIRK_EXTENDED_TMOUT)
+				del_timer(&host->dto_timer);
+
 			/* if there is an error report DATA_ERROR */
 			mci_writel(host, RINTSTS, DW_MCI_DATA_ERROR_FLAGS);
 			host->data_status = pending;
 			smp_wmb(); /* drain writebuffer */
 			set_bit(EVENT_DATA_ERROR, &host->pending_events);
+
+			if (host->quirks & DW_MMC_QUIRK_EXTENDED_TMOUT)
+				/* In case of error, we cannot expect a DTO */
+				set_bit(EVENT_DATA_COMPLETE,
+					&host->pending_events);
+
 			tasklet_schedule(&host->tasklet);
 
 			spin_unlock(&host->irq_lock);

drivers/mmc/host/dw_mmc.h

@@ -118,6 +118,7 @@ struct dw_mci_dma_slave {
  * @part_buf: Simple buffer for partial fifo reads/writes.
  * @push_data: Pointer to FIFO push function.
  * @pull_data: Pointer to FIFO pull function.
+ * @quirks: Set of quirks that apply to specific versions of the IP.
  * @vqmmc_enabled: Status of vqmmc, should be true or false.
  * @irq_flags: The flags to be passed to request_irq.
  * @irq: The irq value to be passed to request_irq.
@@ -223,6 +224,7 @@ struct dw_mci {
 	void (*push_data)(struct dw_mci *host, void *buf, int cnt);
 	void (*pull_data)(struct dw_mci *host, void *buf, int cnt);
 
+	u32			quirks;
 	bool			vqmmc_enabled;
 	unsigned long		irq_flags; /* IRQ flags */
 	int			irq;
@@ -274,6 +276,9 @@ struct dw_mci_board {
 	struct dma_pdata *data;
 };
 
+/* Support for longer data read timeout */
+#define DW_MMC_QUIRK_EXTENDED_TMOUT            BIT(0)
+
 #define DW_MMC_240A		0x240a
 #define DW_MMC_280A		0x280a