[patch 9/9] s3cmci: DMA fixes

Ben Dooks
2009-08-18T11:57:00Z

[-- Attachment #1: s3cmci-dma-fixes.patch --]
[-- Type: text/plain, Size: 5886 bytes --]

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>

---
drivers/mmc/host/s3cmci.c | 62 ++++++++++++++++++++++++++++++++++------------
drivers/mmc/host/s3cmci.h | 3 --
2 files changed, 47 insertions(+), 18 deletions(-)

Index: b/drivers/mmc/host/s3cmci.c
===================================================================
--- a/drivers/mmc/host/s3cmci.c 2009-08-12 13:55:53.000000000 +0100
+++ b/drivers/mmc/host/s3cmci.c 2009-08-12 13:59:28.000000000 +0100
@@ -183,6 +183,21 @@ static inline bool s3cmci_host_usedma(st
#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(str
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 s3cm
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 s3c
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 s3c
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 s3c
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
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
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
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
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(struc
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);

Index: b/drivers/mmc/host/s3cmci.h
===================================================================
--- a/drivers/mmc/host/s3cmci.h 2009-08-12 13:54:49.000000000 +0100
+++ b/drivers/mmc/host/s3cmci.h 2009-08-12 13:59:28.000000000 +0100
@@ -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,

--