mmc: dw_mmc: add xfer timer for avoid DTO without actual data payload

It has proved the controller has a potention broken state with a DTO
interrupt comes while the data payload is missing, which was not
covered by current software state machine. Add a xfer timer to work
around this buggy behaviour introduced by broken design.

Change-Id: I5019c5ba0cdeb59adcdd3a5231a2000b448762bc
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>

drivers/mmc/host/dw_mmc-rockchip.c

@@ -301,6 +301,12 @@ static int dw_mci_rockchip_init(struct dw_mci *host)
 				    "rockchip,rk3288-dw-mshc"))
 		host->bus_hz /= RK3288_CLKGEN_DIV;
 
+	if (of_device_is_compatible(host->dev->of_node,
+				    "rockchip,rk3308-dw-mshc"))
+		host->need_xfer_timer = true;
+	else
+		host->need_xfer_timer = false;
+
 	return 0;
 }
 

drivers/mmc/host/dw_mmc.c

@@ -517,6 +517,10 @@ static void dw_mci_dmac_complete_dma(void *arg)
 		set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
 		tasklet_schedule(&host->tasklet);
 	}
+
+	if (host->need_xfer_timer &&
+	    host->dir_status == DW_MCI_RECV_STATUS)
+		del_timer(&host->xfer_timer);
 }
 
 static int dw_mci_idmac_init(struct dw_mci *host)
@@ -1971,6 +1975,30 @@ static void dw_mci_set_drto(struct dw_mci *host)
 	spin_unlock_irqrestore(&host->irq_lock, irqflags);
 }
 
+static void dw_mci_set_xfer_timeout(struct dw_mci *host)
+{
+	unsigned int xfer_clks;
+	unsigned int xfer_div;
+	unsigned int xfer_ms;
+	unsigned long irqflags;
+
+	xfer_clks = mci_readl(host, TMOUT) >> 8;
+	xfer_div = (mci_readl(host, CLKDIV) & 0xff) * 2;
+	if (xfer_div == 0)
+		xfer_div = 1;
+	xfer_ms = DIV_ROUND_UP_ULL((u64)MSEC_PER_SEC * xfer_clks * xfer_div,
+				   host->bus_hz);
+
+	/* add a bit spare time */
+	xfer_ms += 10;
+
+	spin_lock_irqsave(&host->irq_lock, irqflags);
+	if (!test_bit(EVENT_XFER_COMPLETE, &host->pending_events))
+		mod_timer(&host->xfer_timer,
+			  jiffies + msecs_to_jiffies(xfer_ms));
+	spin_unlock_irqrestore(&host->irq_lock, irqflags);
+}
+
 static bool dw_mci_clear_pending_cmd_complete(struct dw_mci *host)
 {
 	if (!test_bit(EVENT_CMD_COMPLETE, &host->pending_events))
@@ -2109,6 +2137,9 @@ static void dw_mci_tasklet_func(unsigned long priv)
 				 */
 				if (host->dir_status == DW_MCI_RECV_STATUS)
 					dw_mci_set_drto(host);
+				if (host->need_xfer_timer &&
+				    host->dir_status == DW_MCI_RECV_STATUS)
+					dw_mci_set_xfer_timeout(host);
 				break;
 			}
 
@@ -2583,6 +2614,8 @@ done:
 	host->sg = NULL;
 	smp_wmb(); /* drain writebuffer */
 	set_bit(EVENT_XFER_COMPLETE, &host->pending_events);
+	if (host->need_xfer_timer)
+		del_timer(&host->xfer_timer);
 }
 
 static void dw_mci_write_data_pio(struct dw_mci *host)
@@ -2695,6 +2728,9 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
 			del_timer(&host->cto_timer);
 			mci_writel(host, RINTSTS, DW_MCI_CMD_ERROR_FLAGS);
 			host->cmd_status = pending;
+			if ((host->need_xfer_timer) &&
+			     host->dir_status == DW_MCI_RECV_STATUS)
+				del_timer(&host->xfer_timer);
 			smp_wmb(); /* drain writebuffer */
 			set_bit(EVENT_CMD_COMPLETE, &host->pending_events);
 
@@ -3086,6 +3122,36 @@ exit:
 	spin_unlock_irqrestore(&host->irq_lock, irqflags);
 }
 
+static void dw_mci_xfer_timer(struct timer_list *t)
+{
+	struct dw_mci *host = from_timer(host, t, dto_timer);
+	unsigned long irqflags;
+
+	spin_lock_irqsave(&host->irq_lock, irqflags);
+
+	if (test_bit(EVENT_XFER_COMPLETE, &host->pending_events)) {
+		/* Presumably interrupt handler couldn't delete the timer */
+		dev_warn(host->dev, "xfer when already completed\n");
+		goto exit;
+	}
+
+	switch (host->state) {
+	case STATE_SENDING_DATA:
+		host->data_status = SDMMC_INT_DRTO;
+		set_bit(EVENT_DATA_ERROR, &host->pending_events);
+		set_bit(EVENT_DATA_COMPLETE, &host->pending_events);
+		tasklet_schedule(&host->tasklet);
+		break;
+	default:
+		dev_warn(host->dev, "Unexpected xfer timeout, state %d\n",
+			 host->state);
+		break;
+	}
+
+exit:
+	spin_unlock_irqrestore(&host->irq_lock, irqflags);
+}
+
 static void dw_mci_dto_timer(struct timer_list *t)
 {
 	struct dw_mci *host = from_timer(host, t, dto_timer);
@@ -3282,6 +3348,8 @@ int dw_mci_probe(struct dw_mci *host)
 	timer_setup(&host->cmd11_timer, dw_mci_cmd11_timer, 0);
 	timer_setup(&host->cto_timer, dw_mci_cto_timer, 0);
 	timer_setup(&host->dto_timer, dw_mci_dto_timer, 0);
+	if (host->need_xfer_timer)
+		timer_setup(&host->xfer_timer, dw_mci_xfer_timer, 0);
 
 	spin_lock_init(&host->lock);
 	spin_lock_init(&host->irq_lock);

drivers/mmc/host/dw_mmc.h

@@ -234,6 +234,8 @@ struct dw_mci {
 	struct timer_list       cmd11_timer;
 	struct timer_list       cto_timer;
 	struct timer_list       dto_timer;
+	bool			need_xfer_timer;
+	struct timer_list       xfer_timer;
 };
 
 /* DMA ops for Internal/External DMAC interface */