s3cmci: DMA fixes

Fixes for the DMA transfer mode of the driver to try and improve the state
of the code:

- Ensure that dma_complete is set during the end of the command phase
  so that transfers do not stall awaiting the completion

- Update the DMA debugging to provide a bit more useful information
  such as how many DMA descriptors where not processed and print the
  DMA addresses in hexadecimal.

- Fix the DMA channel request code to actually request DMA for the
  S3CMCI block instead of whatever '0' signified.

- Add fallback to PIO if we cannot get the DMA channel, as many of the
  devices with this block only have a limited number of DMA channels.

- Only try and claim and free the DMA channel if we are trying to use it.

This improves the driver DMA code to the point where it can now identify a
card and read the partition table.  However the DMA can still stall when
trying to move data between the host and memory.

Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/mmc/host/s3cmci.c b/drivers/mmc/host/s3cmci.c
index 0adf31895f2a81842bcf3c238a94d0efa274effd..0af972275d45acd47d6646c1b0e1677ae1248929 100644 (file)
--- a/drivers/mmc/host/s3cmci.c
+++ b/drivers/mmc/host/s3cmci.c
@@ -183,6 +183,21 @@ static inline bool s3cmci_host_usedma(struct s3cmci_host *host)
 #endif
 }
 
+/**
+ * s3cmci_host_canpio - return true if host has pio code available
+ *
+ * Return true if the driver has been compiled with the PIO support code
+ * available.
+ */
+static inline bool s3cmci_host_canpio(void)
+{
+#ifdef CONFIG_MMC_S3C_PIO
+       return true;
+#else
+       return false;
+#endif
+}
+
 static inline u32 enable_imask(struct s3cmci_host *host, u32 imask)
 {
        u32 newmask;
@@ -786,6 +801,7 @@ static void s3cmci_dma_done_callback(struct s3c2410_dma_chan *dma_ch,
        dbg(host, dbg_dma, "DMA FINISHED Size:%i DSTA:%08x DCNT:%08x\n",
                size, mci_dsta, mci_dcnt);
 
+       host->dma_complete = 1;
        host->complete_what = COMPLETION_FINALIZE;
 
 out:
@@ -816,7 +832,8 @@ static void finalize_request(struct s3cmci_host *host)
        if (cmd->data && (cmd->error == 0) &&
            (cmd->data->error == 0)) {
                if (s3cmci_host_usedma(host) && (!host->dma_complete)) {
-                       dbg(host, dbg_dma, "DMA Missing!\n");
+                       dbg(host, dbg_dma, "DMA Missing (%d)!\n",
+                           host->dma_complete);
                        return;
                }
        }
@@ -1065,7 +1082,7 @@ static int s3cmci_prepare_pio(struct s3cmci_host *host, struct mmc_data *data)
 static int s3cmci_prepare_dma(struct s3cmci_host *host, struct mmc_data *data)
 {
        int dma_len, i;
-       int rw = (data->flags & MMC_DATA_WRITE) ? 1 : 0;
+       int rw = data->flags & MMC_DATA_WRITE;
 
        BUG_ON((data->flags & BOTH_DIR) == BOTH_DIR);
 
@@ -1073,7 +1090,7 @@ static int s3cmci_prepare_dma(struct s3cmci_host *host, struct mmc_data *data)
        s3c2410_dma_ctrl(host->dma, S3C2410_DMAOP_FLUSH);
 
        dma_len = dma_map_sg(mmc_dev(host->mmc), data->sg, data->sg_len,
-                            (rw) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
+                            rw ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
 
        if (dma_len == 0)
                return -ENOMEM;
@@ -1084,11 +1101,11 @@ static int s3cmci_prepare_dma(struct s3cmci_host *host, struct mmc_data *data)
        for (i = 0; i < dma_len; i++) {
                int res;
 
-               dbg(host, dbg_dma, "enqueue %i:%u@%u\n", i,
-                       sg_dma_address(&data->sg[i]),
-                       sg_dma_len(&data->sg[i]));
+               dbg(host, dbg_dma, "enqueue %i: %08x@%u\n", i,
+                   sg_dma_address(&data->sg[i]),
+                   sg_dma_len(&data->sg[i]));
 
-               res = s3c2410_dma_enqueue(host->dma, (void *) host,
+               res = s3c2410_dma_enqueue(host->dma, host,
                                          sg_dma_address(&data->sg[i]),
                                          sg_dma_len(&data->sg[i]));
 
@@ -1581,8 +1598,6 @@ static int __devinit s3cmci_probe(struct platform_device *pdev)
        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
@@ -1665,10 +1680,21 @@ static int __devinit s3cmci_probe(struct platform_device *pdev)
                gpio_direction_input(host->pdata->gpio_wprotect);
        }
 
-       if (s3c2410_dma_request(S3CMCI_DMA, &s3cmci_dma_client, NULL) < 0) {
-               dev_err(&pdev->dev, "unable to get DMA channel.\n");
-               ret = -EBUSY;
-               goto probe_free_gpio_wp;
+       /* depending on the dma state, get a dma channel to use. */
+
+       if (s3cmci_host_usedma(host)) {
+               host->dma = s3c2410_dma_request(DMACH_SDI, &s3cmci_dma_client,
+                                               host);
+               if (host->dma < 0) {
+                       dev_err(&pdev->dev, "cannot get DMA channel.\n");
+                       if (!s3cmci_host_canpio()) {
+                               ret = -EBUSY;
+                               goto probe_free_gpio_wp;
+                       } else {
+                               dev_warn(&pdev->dev, "falling back to PIO.\n");
+                               host->dodma = 0;
+                       }
+               }
        }
 
        host->clk = clk_get(&pdev->dev, "sdi");
@@ -1676,7 +1702,7 @@ static int __devinit s3cmci_probe(struct platform_device *pdev)
                dev_err(&pdev->dev, "failed to find clock source.\n");
                ret = PTR_ERR(host->clk);
                host->clk = NULL;
-               goto probe_free_host;
+               goto probe_free_dma;
        }
 
        ret = clk_enable(host->clk);
@@ -1738,6 +1764,10 @@ static int __devinit s3cmci_probe(struct platform_device *pdev)
  clk_free:
        clk_put(host->clk);
 
+ probe_free_dma:
+       if (s3cmci_host_usedma(host))
+               s3c2410_dma_free(host->dma, &s3cmci_dma_client);
+
  probe_free_gpio_wp:
        if (host->pdata->gpio_wprotect)
                gpio_free(host->pdata->gpio_wprotect);
@@ -1796,7 +1826,9 @@ static int __devexit s3cmci_remove(struct platform_device *pdev)
        clk_put(host->clk);
 
        tasklet_disable(&host->pio_tasklet);
-       s3c2410_dma_free(S3CMCI_DMA, &s3cmci_dma_client);
+
+       if (s3cmci_host_usedma(host))
+               s3c2410_dma_free(host->dma, &s3cmci_dma_client);
 
        free_irq(host->irq, host);
 

diff --git a/drivers/mmc/host/s3cmci.h b/drivers/mmc/host/s3cmci.h
index 62fac66023065b3e35061be42c6ef232d638ab45..c76b53dbeb6179a3545bbb26b7aa87d50302477e 100644 (file)
--- a/drivers/mmc/host/s3cmci.h
+++ b/drivers/mmc/host/s3cmci.h
@@ -8,9 +8,6 @@
  * published by the Free Software Foundation.
  */
 
-/* FIXME: DMA Resource management ?! */
-#define S3CMCI_DMA 0
-
 enum s3cmci_waitfor {
        COMPLETION_NONE,
        COMPLETION_FINALIZE,