2 files changed, 65 insertions, 8 deletions

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 7cb057f3f883..cf6a6545240b 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -276,6 +276,40 @@ config MMC_S3C
 
           If unsure, say N.
 
+choice
+        prompt "Samsung S3C SD/MMC transfer code"
+        depends on MMC_S3C
+
+config MMC_S3C_PIO
+        bool "Use PIO transfers only"
+        help
+          Use PIO to transfer data between memory and the hardware.
+
+          PIO is slower than DMA as it requires CPU instructions to
+          move the data. This has been the traditional default for
+          the S3C MCI driver.
+
+config MMC_S3C_DMA
+        bool "Use DMA transfers only (EXPERIMENTAL)"
+        depends on EXPERIMENTAL
+        help
+          Use DMA to transfer data between memory and the hardare.
+
+          Currently, the DMA support in this driver seems to not be
+          working properly and needs to be debugged before this
+          option is useful.
+
+config MMC_S3C_PIODMA
+        bool "Support for both PIO and DMA (EXPERIMENTAL)"
+        help
+          Compile both the PIO and DMA transfer routines into the
+          driver and let the platform select at run-time which one
+          is best.
+
+          See notes for the DMA option.
+
+endchoice
+
 config MMC_SDRICOH_CS
         tristate "MMC/SD driver for Ricoh Bay1Controllers (EXPERIMENTAL)"
         depends on EXPERIMENTAL && PCI && PCMCIA
diff --git a/drivers/mmc/host/s3cmci.c b/drivers/mmc/host/s3cmci.c
index 7660ac4572e5..0adf31895f2a 100644
--- a/drivers/mmc/host/s3cmci.c
+++ b/drivers/mmc/host/s3cmci.c
@@ -164,6 +164,25 @@ static void dbg_dumpregs(struct s3cmci_host *host, char *prefix) { }
 
 #endif /* CONFIG_MMC_DEBUG */
 
+/**
+ * s3cmci_host_usedma - return whether the host is using dma or pio
+ * @host: The host state
+ *
+ * Return true if the host is using DMA to transfer data, else false
+ * to use PIO mode. Will return static data depending on the driver
+ * configuration.
+ */
+static inline bool s3cmci_host_usedma(struct s3cmci_host *host)
+{
+#ifdef CONFIG_MMC_S3C_PIO
+        return false;
+#elif defined(CONFIG_MMC_S3C_DMA)
+        return true;
+#else
+        return host->dodma;
+#endif
+}
+
 static inline u32 enable_imask(struct s3cmci_host *host, u32 imask)
 {
         u32 newmask;
@@ -560,7 +579,7 @@ static irqreturn_t s3cmci_irq(int irq, void *dev_id)
                 goto irq_out;
         }
 
-        if (!host->dodma) {
+        if (!s3cmci_host_usedma(host)) {
                 if ((host->pio_active == XFER_WRITE) &&
                     (mci_fsta & S3C2410_SDIFSTA_TFDET)) {
 
@@ -796,7 +815,7 @@ static void finalize_request(struct s3cmci_host *host)
 
         if (cmd->data && (cmd->error == 0) &&
             (cmd->data->error == 0)) {
-                if (host->dodma && (!host->dma_complete)) {
+                if (s3cmci_host_usedma(host) && (!host->dma_complete)) {
                         dbg(host, dbg_dma, "DMA Missing!\n");
                         return;
                 }
@@ -848,7 +867,7 @@ static void finalize_request(struct s3cmci_host *host)
         /* If we had an error while transfering data we flush the
          * DMA channel and the fifo to clear out any garbage. */
         if (mrq->data->error != 0) {
-                if (host->dodma)
+                if (s3cmci_host_usedma(host))
                         s3c2410_dma_ctrl(host->dma, S3C2410_DMAOP_FLUSH);
 
                 if (host->is2440) {
@@ -968,7 +987,7 @@ static int s3cmci_setup_data(struct s3cmci_host *host, struct mmc_data *data)
 
         dcon  = data->blocks & S3C2410_SDIDCON_BLKNUM_MASK;
 
-        if (host->dodma)
+        if (s3cmci_host_usedma(host))
                 dcon |= S3C2410_SDIDCON_DMAEN;
 
         if (host->bus_width == MMC_BUS_WIDTH_4)
@@ -1114,7 +1133,7 @@ static void s3cmci_send_request(struct mmc_host *mmc)
                         return;
                 }
 
-                if (host->dodma)
+                if (s3cmci_host_usedma(host))
                         res = s3cmci_prepare_dma(host, cmd->data);
                 else
                         res = s3cmci_prepare_pio(host, cmd->data);
@@ -1398,7 +1417,7 @@ static int s3cmci_state_show(struct seq_file *seq, void *v)
         seq_printf(seq, "IRQ disabled = %d\n", host->irq_disabled);
         seq_printf(seq, "IRQ state = %d\n", host->irq_state);
         seq_printf(seq, "CD IRQ = %d\n", host->irq_cd);
-        seq_printf(seq, "Do DMA = %d\n", host->dodma);
+        seq_printf(seq, "Do DMA = %d\n", s3cmci_host_usedma(host));
         seq_printf(seq, "SDIIMSK at %d\n", host->sdiimsk);
         seq_printf(seq, "SDIDATA at %d\n", host->sdidata);
 
@@ -1559,12 +1578,15 @@ static int __devinit s3cmci_probe(struct platform_device *pdev)
                 host->clk_div   = 2;
         }
 
-        host->dodma             = 0;
         host->complete_what     = COMPLETION_NONE;
         host->pio_active        = XFER_NONE;
 
         host->dma               = S3CMCI_DMA;
 
+#ifdef CONFIG_MMC_S3C_PIODMA
+        host->dodma             = host->pdata->dma;
+#endif
+
         host->mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
         if (!host->mem) {
                 dev_err(&pdev->dev,
@@ -1702,7 +1724,8 @@ static int __devinit s3cmci_probe(struct platform_device *pdev)
         s3cmci_debugfs_attach(host);
 
         platform_set_drvdata(pdev, mmc);
-        dev_info(&pdev->dev, "initialisation done.\n");
+        dev_info(&pdev->dev, "%s - using %s\n", mmc_hostname(mmc),
+                 s3cmci_host_usedma(host) ? "dma" : "pio");
 
         return 0;