mmc: sdhci: Correct the tuning command handle for PIO mode

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 exclude this case.

Signed-off-by: Haibo Chen <[e-mail]>
Acked-by: Adrian Hunter <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[Ulf: Dropped redundant parenthesis in an expression]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/mmc/host/sdhci.c

···
 {
 	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) {