mmc: Allow 2 byte requests in 4-bit mode for tmio_mmc

Adjust the tmio_mmc block size check to accept 2-byte requests in 4-bit
mode if the hardware supports it.

Tested with the SDHI hardware block included in sh7724.
Signed-off-by: Yusuke Goda <yusuke.goda.sx@renesas.com>
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Acked-by: Magnus Damm <damm@opensource.se>
Tested-by: Arnd Hannemann <arnd@arndnet.de>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/sh_mobile_sdhi.c

@@ -125,6 +125,12 @@ static int __devinit sh_mobile_sdhi_probe(struct platform_device *pdev)
 		mmc_data->capabilities |= p->tmio_caps;
 	}
 
+	/*
+	 * All SDHI blocks support 2-byte and larger block sizes in 4-bit
+	 * bus width mode.
+	 */
+	mmc_data->flags |= TMIO_MMC_BLKSZ_2BYTES;
+
 	if (p && p->dma_slave_tx >= 0 && p->dma_slave_rx >= 0) {
 		priv->param_tx.slave_id = p->dma_slave_tx;
 		priv->param_rx.slave_id = p->dma_slave_rx;

drivers/mmc/host/tmio_mmc.c

@@ -658,15 +658,22 @@ static void tmio_mmc_release_dma(struct tmio_mmc_host *host)
 static int tmio_mmc_start_data(struct tmio_mmc_host *host,
 	struct mmc_data *data)
 {
+	struct mfd_cell *cell = host->pdev->dev.platform_data;
+	struct tmio_mmc_data *pdata = cell->driver_data;
+
 	pr_debug("setup data transfer: blocksize %08x  nr_blocks %d\n",
 		 data->blksz, data->blocks);
 
-	/* Hardware cannot perform 1 and 2 byte requests in 4 bit mode */
-	if (data->blksz < 4 && host->mmc->ios.bus_width == MMC_BUS_WIDTH_4) {
+	/* Some hardware cannot perform 2 byte requests in 4 bit mode */
+	if (host->mmc->ios.bus_width == MMC_BUS_WIDTH_4) {
+		int blksz_2bytes = pdata->flags & TMIO_MMC_BLKSZ_2BYTES;
+
+		if (data->blksz < 2 || (data->blksz < 4 && !blksz_2bytes)) {
 			pr_err("%s: %d byte block unsupported in 4 bit mode\n",
 			       mmc_hostname(host->mmc), data->blksz);
 			return -EINVAL;
 		}
+	}
 
 	tmio_mmc_init_sg(host, data);
 	host->data = data;

include/linux/mfd/tmio.h

@@ -52,6 +52,11 @@
 
 /* tmio MMC platform flags */
 #define TMIO_MMC_WRPROTECT_DISABLE	(1 << 0)
+/*
+ * Some controllers can support a 2-byte block size when the bus width
+ * is configured in 4-bit mode.
+ */
+#define TMIO_MMC_BLKSZ_2BYTES		(1 << 1)
 
 int tmio_core_mmc_enable(void __iomem *cnf, int shift, unsigned long base);
 int tmio_core_mmc_resume(void __iomem *cnf, int shift, unsigned long base);