sdhci: handle bug in JMB38x for sizes < 4 bytes

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/host/sdhci-pci.c

@@ -143,7 +143,8 @@ static int jmicron_probe(struct sdhci_pci_chip *chip)
 		chip->quirks |= SDHCI_QUIRK_32BIT_DMA_ADDR |
 			  SDHCI_QUIRK_32BIT_DMA_SIZE |
 			  SDHCI_QUIRK_32BIT_ADMA_SIZE |
-			  SDHCI_QUIRK_RESET_AFTER_REQUEST;
+			  SDHCI_QUIRK_RESET_AFTER_REQUEST |
+			  SDHCI_QUIRK_BROKEN_SMALL_PIO;
 	}
 
 	/*

drivers/mmc/host/sdhci.c

@@ -278,6 +278,15 @@ static void sdhci_transfer_pio(struct sdhci_host *host)
 	else
 		mask = SDHCI_SPACE_AVAILABLE;
 
+	/*
+	 * Some controllers (JMicron JMB38x) mess up the buffer bits
+	 * for transfers < 4 bytes. As long as it is just one block,
+	 * we can ignore the bits.
+	 */
+	if ((host->quirks & SDHCI_QUIRK_BROKEN_SMALL_PIO) &&
+		(host->data->blocks == 1))
+		mask = ~0;
+
 	while (readl(host->ioaddr + SDHCI_PRESENT_STATE) & mask) {
 		if (host->data->flags & MMC_DATA_READ)
 			sdhci_read_block_pio(host);

drivers/mmc/host/sdhci.h

@@ -206,6 +206,8 @@ struct sdhci_host {
 #define SDHCI_QUIRK_NO_SIMULT_VDD_AND_POWER		(1<<11)
 /* Controller provides an incorrect timeout value for transfers */
 #define SDHCI_QUIRK_BROKEN_TIMEOUT_VAL			(1<<12)
+/* Controller has an issue with buffer bits for small transfers */
+#define SDHCI_QUIRK_BROKEN_SMALL_PIO			(1<<13)
 
 	int			irq;		/* Device IRQ */
 	void __iomem *		ioaddr;		/* Mapped address */