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>

3 files changed, 23 insertions, 5 deletions

diff --git a/drivers/mfd/sh_mobile_sdhi.c b/drivers/mfd/sh_mobile_sdhi.c
index 01d83a41d570..f1714f93af9d 100644
--- a/drivers/mfd/sh_mobile_sdhi.c
+++ b/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;
diff --git a/drivers/mmc/host/tmio_mmc.c b/drivers/mmc/host/tmio_mmc.c
index 1a47221d01a4..e7765a89593e 100644
--- a/drivers/mmc/host/tmio_mmc.c
+++ b/drivers/mmc/host/tmio_mmc.c
@@ -658,14 +658,21 @@ 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) {
-                pr_err("%s: %d byte block unsupported in 4 bit mode\n",
-                       mmc_hostname(host->mmc), data->blksz);
-                return -EINVAL;
+        /* 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);
diff --git a/include/linux/mfd/tmio.h b/include/linux/mfd/tmio.h
index 24c43bbad541..085f041197dc 100644
--- a/include/linux/mfd/tmio.h
+++ b/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);