[PATCH] mmc: sdhci: correct the tuning command handle for PIO mode

[haibo.chen@nxp.com]

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

If sdhci use PIO mode, and use mmc_send_tuning() to send the
tuning command, system will stuck because of the storm irq
of sdhci. For PIO mode, use mmc_send_tuning(), it will trigger
buffer_read_ready interrupt and data transfer complete interrupt.
In current code logic, it will directly return in sdhci_data_irq,
can not call the sdhci_transfer_pio(). So the buffer_read_ready
interrupt storm happen. So for standard tuning method, need to
excluse this case.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
---
 drivers/mmc/host/sdhci.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index aba6e10b8605..acee54b368b0 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -3278,8 +3278,14 @@ static void sdhci_data_irq(struct sdhci_host *host, u32 intmask)
 {
 	u32 command;
 
-	/* CMD19 generates _only_ Buffer Read Ready interrupt */
-	if (intmask & SDHCI_INT_DATA_AVAIL) {
+	/*
+	 * CMD19 generates _only_ Buffer Read Ready interrupt if
+	 * use sdhci_send_tuning.
+	 * Need to exclude this case: PIO mode and use mmc_send_tuning,
+	 * If not, sdhci_transfer_pio will never be called, make the
+	 * SDHCI_INT_DATA_AVAIL always there, stuck in irq storm.
+	 */
+	if ((intmask & SDHCI_INT_DATA_AVAIL) && (!host->data)) {
 		command = SDHCI_GET_CMD(sdhci_readw(host, SDHCI_COMMAND));
 		if (command == MMC_SEND_TUNING_BLOCK ||
 		    command == MMC_SEND_TUNING_BLOCK_HS200) {
-- 
2.17.1