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* let the mxcmmc driver use the dmaengine API
@ 2011-01-12 10:09 Sascha Hauer
  2011-01-12 10:09 ` [PATCH] mxcmmc: use " Sascha Hauer
  0 siblings, 1 reply; 6+ messages in thread
From: Sascha Hauer @ 2011-01-12 10:09 UTC (permalink / raw)
  To: linux-arm-kernel

This saves us several ifdefs and also adds mxcmmc DMA support for the
i.MX31 processor.

Sascha

Sascha Hauer (1):
      mxcmmc: use dmaengine API

 drivers/mmc/host/mxcmmc.c |  172 +++++++++++++++++++++++++--------------------
 1 files changed, 97 insertions(+), 75 deletions(-)

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] mxcmmc: use dmaengine API
  2011-01-12 10:09 let the mxcmmc driver use the dmaengine API Sascha Hauer
@ 2011-01-12 10:09 ` Sascha Hauer
  2011-01-12 10:26   ` Russell King - ARM Linux
  2011-01-12 12:25   ` Shawn Guo
  0 siblings, 2 replies; 6+ messages in thread
From: Sascha Hauer @ 2011-01-12 10:09 UTC (permalink / raw)
  To: linux-arm-kernel

This switches the mxcmmc driver to use the dmaengine API. Unlike
the old one this one is always present in the tree, even if no DMA
is implement, hence we can remove all the #ifdefs in from the driver.
The driver automatically switches to PIO mode if no DMA support or no
suitable channel is available.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/mmc/host/mxcmmc.c |  172 +++++++++++++++++++++++++--------------------
 1 files changed, 97 insertions(+), 75 deletions(-)

diff --git a/drivers/mmc/host/mxcmmc.c b/drivers/mmc/host/mxcmmc.c
index bdd2cbb..5de4bf8 100644
--- a/drivers/mmc/host/mxcmmc.c
+++ b/drivers/mmc/host/mxcmmc.c
@@ -31,16 +31,14 @@
 #include <linux/clk.h>
 #include <linux/io.h>
 #include <linux/gpio.h>
+#include <linux/dmaengine.h>
 
 #include <asm/dma.h>
 #include <asm/irq.h>
 #include <asm/sizes.h>
 #include <mach/mmc.h>
 
-#ifdef CONFIG_ARCH_MX2
-#include <mach/dma-mx1-mx2.h>
-#define HAS_DMA
-#endif
+#include <mach/dma.h>
 
 #define DRIVER_NAME "mxc-mmc"
 
@@ -117,7 +115,8 @@ struct mxcmci_host {
 	void __iomem		*base;
 	int			irq;
 	int			detect_irq;
-	int			dma;
+	struct dma_chan		*dma;
+	struct dma_async_tx_descriptor *desc;
 	int			do_dma;
 	int			default_irq_mask;
 	int			use_sdio;
@@ -141,6 +140,11 @@ struct mxcmci_host {
 
 	struct work_struct	datawork;
 	spinlock_t		lock;
+
+	int			burstlen;
+	int			dmareq;
+	struct dma_slave_config dma_slave_config;
+	struct imx_dma_data	dma_data;
 };
 
 static void mxcmci_set_clk_rate(struct mxcmci_host *host, unsigned int clk_ios);
@@ -166,17 +170,16 @@ static void mxcmci_softreset(struct mxcmci_host *host)
 
 	writew(0xff, host->base + MMC_REG_RES_TO);
 }
+static int mxcmci_setup_dma(struct mmc_host *mmc);
 
 static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
 {
 	unsigned int nob = data->blocks;
 	unsigned int blksz = data->blksz;
 	unsigned int datasize = nob * blksz;
-#ifdef HAS_DMA
 	struct scatterlist *sg;
 	int i;
-	int ret;
-#endif
+
 	if (data->flags & MMC_DATA_STREAM)
 		nob = 0xffff;
 
@@ -187,7 +190,9 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
 	writew(blksz, host->base + MMC_REG_BLK_LEN);
 	host->datasize = datasize;
 
-#ifdef HAS_DMA
+	if (!mxcmci_use_dma(host))
+		return 0;
+
 	for_each_sg(data->sg, sg, data->sg_len, i) {
 		if (sg->offset & 3 || sg->length & 3) {
 			host->do_dma = 0;
@@ -195,34 +200,25 @@ static int mxcmci_setup_data(struct mxcmci_host *host, struct mmc_data *data)
 		}
 	}
 
-	if (data->flags & MMC_DATA_READ) {
+	if (data->flags & MMC_DATA_READ)
 		host->dma_dir = DMA_FROM_DEVICE;
-		host->dma_nents = dma_map_sg(mmc_dev(host->mmc), data->sg,
-					     data->sg_len,  host->dma_dir);
-
-		ret = imx_dma_setup_sg(host->dma, data->sg, host->dma_nents,
-				datasize,
-				host->res->start + MMC_REG_BUFFER_ACCESS,
-				DMA_MODE_READ);
-	} else {
+	else
 		host->dma_dir = DMA_TO_DEVICE;
-		host->dma_nents = dma_map_sg(mmc_dev(host->mmc), data->sg,
-					     data->sg_len,  host->dma_dir);
 
-		ret = imx_dma_setup_sg(host->dma, data->sg, host->dma_nents,
-				datasize,
-				host->res->start + MMC_REG_BUFFER_ACCESS,
-				DMA_MODE_WRITE);
-	}
+	host->dma_nents = dma_map_sg(mmc_dev(host->mmc), data->sg,
+				     data->sg_len,  host->dma_dir);
+	host->desc = host->dma->device->device_prep_slave_sg(host->dma,
+		data->sg, data->sg_len, host->dma_dir,
+		DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 
-	if (ret) {
-		dev_err(mmc_dev(host->mmc), "failed to setup DMA : %d\n", ret);
-		return ret;
+	if (!host->desc) {
+		dev_err(mmc_dev(host->mmc), "failed to setup DMA\n");
+		return -EINVAL;
 	}
 	wmb();
 
-	imx_dma_enable(host->dma);
-#endif /* HAS_DMA */
+	dmaengine_submit(host->desc);
+
 	return 0;
 }
 
@@ -297,13 +293,11 @@ static int mxcmci_finish_data(struct mxcmci_host *host, unsigned int stat)
 	struct mmc_data *data = host->data;
 	int data_error;
 
-#ifdef HAS_DMA
 	if (mxcmci_use_dma(host)) {
-		imx_dma_disable(host->dma);
+		dmaengine_terminate_all(host->dma);
 		dma_unmap_sg(mmc_dev(host->mmc), data->sg, host->dma_nents,
 				host->dma_dir);
 	}
-#endif
 
 	if (stat & STATUS_ERR_MASK) {
 		dev_dbg(mmc_dev(host->mmc), "request failed. status: 0x%08x\n",
@@ -505,7 +499,6 @@ static void mxcmci_datawork(struct work_struct *work)
 	}
 }
 
-#ifdef HAS_DMA
 static void mxcmci_data_done(struct mxcmci_host *host, unsigned int stat)
 {
 	struct mmc_data *data = host->data;
@@ -528,7 +521,6 @@ static void mxcmci_data_done(struct mxcmci_host *host, unsigned int stat)
 		mxcmci_finish_request(host, host->req);
 	}
 }
-#endif /* HAS_DMA */
 
 static void mxcmci_cmd_done(struct mxcmci_host *host, unsigned int stat)
 {
@@ -566,12 +558,10 @@ static irqreturn_t mxcmci_irq(int irq, void *devid)
 	sdio_irq = (stat & STATUS_SDIO_INT_ACTIVE) && host->use_sdio;
 	spin_unlock_irqrestore(&host->lock, flags);
 
-#ifdef HAS_DMA
 	if (mxcmci_use_dma(host) &&
 	    (stat & (STATUS_READ_OP_DONE | STATUS_WRITE_OP_DONE)))
 		writel(STATUS_READ_OP_DONE | STATUS_WRITE_OP_DONE,
 			host->base + MMC_REG_STATUS);
-#endif
 
 	if (sdio_irq) {
 		writel(STATUS_SDIO_INT_ACTIVE, host->base + MMC_REG_STATUS);
@@ -581,14 +571,14 @@ static irqreturn_t mxcmci_irq(int irq, void *devid)
 	if (stat & STATUS_END_CMD_RESP)
 		mxcmci_cmd_done(host, stat);
 
-#ifdef HAS_DMA
 	if (mxcmci_use_dma(host) &&
 		  (stat & (STATUS_DATA_TRANS_DONE | STATUS_WRITE_OP_DONE)))
 		mxcmci_data_done(host, stat);
-#endif
+
 	if (host->default_irq_mask &&
 		  (stat & (STATUS_CARD_INSERTION | STATUS_CARD_REMOVAL)))
 		mmc_detect_change(host->mmc, msecs_to_jiffies(200));
+
 	return IRQ_HANDLED;
 }
 
@@ -602,9 +592,7 @@ static void mxcmci_request(struct mmc_host *mmc, struct mmc_request *req)
 
 	host->req = req;
 	host->cmdat &= ~CMD_DAT_CONT_INIT;
-#ifdef HAS_DMA
-	host->do_dma = 1;
-#endif
+
 	if (req->data) {
 		error = mxcmci_setup_data(host, req->data);
 		if (error) {
@@ -620,6 +608,7 @@ static void mxcmci_request(struct mmc_host *mmc, struct mmc_request *req)
 	}
 
 	error = mxcmci_start_cmd(host, req->cmd, cmdat);
+
 out:
 	if (error)
 		mxcmci_finish_request(host, req);
@@ -658,22 +647,47 @@ static void mxcmci_set_clk_rate(struct mxcmci_host *host, unsigned int clk_ios)
 			prescaler, divider, clk_in, clk_ios);
 }
 
+static int mxcmci_setup_dma(struct mmc_host *mmc)
+{
+	struct mxcmci_host *host = mmc_priv(mmc);
+	struct dma_slave_config *config = &host->dma_slave_config;
+
+	config->direction = DMA_FROM_DEVICE;
+	config->dst_addr = host->res->start + MMC_REG_BUFFER_ACCESS;
+	config->src_addr = host->res->start + MMC_REG_BUFFER_ACCESS;
+	config->dst_addr_width = 4;
+	config->src_addr_width = 4;
+	config->dst_maxburst = host->burstlen;
+	config->src_maxburst = host->burstlen;
+
+	return dmaengine_slave_config(host->dma, config);
+}
+
 static void mxcmci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 {
 	struct mxcmci_host *host = mmc_priv(mmc);
-#ifdef HAS_DMA
-	unsigned int blen;
+	int burstlen, ret;
+
 	/*
 	 * use burstlen of 64 in 4 bit mode (--> reg value  0)
 	 * use burstlen of 16 in 1 bit mode (--> reg value 16)
 	 */
 	if (ios->bus_width == MMC_BUS_WIDTH_4)
-		blen = 0;
+		burstlen = 64;
 	else
-		blen = 16;
+		burstlen = 16;
+
+	if (mxcmci_use_dma(host) && burstlen != host->burstlen) {
+		host->burstlen = burstlen;
+		ret = mxcmci_setup_dma(mmc);
+		if (ret) {
+			dev_err(mmc_dev(host->mmc),
+				"failed to config DMA channel. Falling back to PIO\n");
+			dma_release_channel(host->dma);
+			host->do_dma = 0;
+		}
+	}
 
-	imx_dma_config_burstlen(host->dma, blen);
-#endif
 	if (ios->bus_width == MMC_BUS_WIDTH_4)
 		host->cmdat |= CMD_DAT_CONT_BUS_WIDTH_4;
 	else
@@ -754,6 +768,20 @@ static void mxcmci_init_card(struct mmc_host *host, struct mmc_card *card)
 		host->caps |= MMC_CAP_4_BIT_DATA;
 }
 
+static bool filter(struct dma_chan *chan, void *param)
+{
+	struct mxcmci_host *host = param;
+
+	if (!imx_dma_is_general_purpose(chan)) {
+		printk("no general\n");
+		return false;
+	}
+
+        chan->private = &host->dma_data;
+
+        return true;
+}
+
 static const struct mmc_host_ops mxcmci_ops = {
 	.request		= mxcmci_request,
 	.set_ios		= mxcmci_set_ios,
@@ -768,6 +796,7 @@ static int mxcmci_probe(struct platform_device *pdev)
 	struct mxcmci_host *host = NULL;
 	struct resource *iores, *r;
 	int ret = 0, irq;
+	dma_cap_mask_t mask;
 
 	printk(KERN_INFO "i.MX SDHC driver\n");
 
@@ -794,7 +823,7 @@ static int mxcmci_probe(struct platform_device *pdev)
 	mmc->max_blk_size = 2048;
 	mmc->max_blk_count = 65535;
 	mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
-	mmc->max_seg_size = mmc->max_req_size;
+	mmc->max_seg_size = 65535;
 
 	host = mmc_priv(mmc);
 	host->base = ioremap(r->start, resource_size(r));
@@ -846,29 +875,22 @@ static int mxcmci_probe(struct platform_device *pdev)
 
 	writel(host->default_irq_mask, host->base + MMC_REG_INT_CNTR);
 
-#ifdef HAS_DMA
-	host->dma = imx_dma_request_by_prio(DRIVER_NAME, DMA_PRIO_LOW);
-	if (host->dma < 0) {
-		dev_err(mmc_dev(host->mmc), "imx_dma_request_by_prio failed\n");
-		ret = -EBUSY;
-		goto out_clk_put;
-	}
-
 	r = platform_get_resource(pdev, IORESOURCE_DMA, 0);
-	if (!r) {
-		ret = -EINVAL;
-		goto out_free_dma;
+	if (r) {
+		host->dmareq = r->start;
+		host->dma_data.peripheral_type = IMX_DMATYPE_SDHC;
+		host->dma_data.priority = DMA_PRIO_LOW;
+		host->dma_data.dma_request = host->dmareq;
+		dma_cap_zero(mask);
+		dma_cap_set(DMA_SLAVE, mask);
+		host->dma = dma_request_channel(mask, filter, host);
+		if (host->dma)
+			host->do_dma = 1;
 	}
 
-	ret = imx_dma_config_channel(host->dma,
-				     IMX_DMA_MEMSIZE_32 | IMX_DMA_TYPE_FIFO,
-				     IMX_DMA_MEMSIZE_32 | IMX_DMA_TYPE_LINEAR,
-				     r->start, 0);
-	if (ret) {
-		dev_err(mmc_dev(host->mmc), "failed to config DMA channel\n");
-		goto out_free_dma;
-	}
-#endif
+	if (!host->do_dma)
+		dev_info(mmc_dev(host->mmc), "dma not available. Using PIO\n");
+
 	INIT_WORK(&host->datawork, mxcmci_datawork);
 
 	ret = request_irq(host->irq, mxcmci_irq, 0, DRIVER_NAME, host);
@@ -891,9 +913,8 @@ static int mxcmci_probe(struct platform_device *pdev)
 out_free_irq:
 	free_irq(host->irq, host);
 out_free_dma:
-#ifdef HAS_DMA
-	imx_dma_free(host->dma);
-#endif
+	if (host->dma)
+		dma_release_channel(host->dma);
 out_clk_put:
 	clk_disable(host->clk);
 	clk_put(host->clk);
@@ -920,9 +941,10 @@ static int mxcmci_remove(struct platform_device *pdev)
 
 	free_irq(host->irq, host);
 	iounmap(host->base);
-#ifdef HAS_DMA
-	imx_dma_free(host->dma);
-#endif
+
+	if (host->dma)
+		dma_release_channel(host->dma);
+
 	clk_disable(host->clk);
 	clk_put(host->clk);
 
-- 
1.7.2.3

^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH] mxcmmc: use dmaengine API
  2011-01-12 10:09 ` [PATCH] mxcmmc: use " Sascha Hauer
@ 2011-01-12 10:26   ` Russell King - ARM Linux
  2011-01-12 13:13     ` Sascha Hauer
  2011-01-12 12:25   ` Shawn Guo
  1 sibling, 1 reply; 6+ messages in thread
From: Russell King - ARM Linux @ 2011-01-12 10:26 UTC (permalink / raw)
  To: linux-arm-kernel

On Wed, Jan 12, 2011 at 11:09:56AM +0100, Sascha Hauer wrote:
> +	host->dma_nents = dma_map_sg(mmc_dev(host->mmc), data->sg,
> +				     data->sg_len,  host->dma_dir);

As recently discussed, you don't need to save dma_nents - the value to
be passed to dma_unmap_sg() is data->sg_len, not host->dma_nents.

You should also do the map/unmap against the DMA engine device (which
is the device actually doing DMA) rather than the peripheral (which is
only the recipient of DMA).  The reason is - while the peripheral can
see the DMA controller, the peripheral may be able to see all RAM but
the DMA controller may have an IOMMU or limited view of RAM.

> +static int mxcmci_setup_dma(struct mmc_host *mmc)
> +{
> +	struct mxcmci_host *host = mmc_priv(mmc);
> +	struct dma_slave_config *config = &host->dma_slave_config;
> +
> +	config->direction = DMA_FROM_DEVICE;

I would like to get some concensus on removing config->direction from
the slave configuration entirely - and make all the fields below
refer purely to the peripheral device parameters.  At the moment,
the API allows them to be used ambiguously.

> +static bool filter(struct dma_chan *chan, void *param)
> +{
> +	struct mxcmci_host *host = param;
> +
> +	if (!imx_dma_is_general_purpose(chan)) {
> +		printk("no general\n");
> +		return false;
> +	}
> +
> +        chan->private = &host->dma_data;
> +
> +        return true;

Looks like something went wrong with the tabbing here?

> @@ -794,7 +823,7 @@ static int mxcmci_probe(struct platform_device *pdev)
>  	mmc->max_blk_size = 2048;
>  	mmc->max_blk_count = 65535;
>  	mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
> -	mmc->max_seg_size = mmc->max_req_size;
> +	mmc->max_seg_size = 65535;

You can get this from the DMA parameters for the DMA engine device:

	mmc->max_seg_size = dma_get_max_seg_size(dev);

where 'dev' is the DMA engine struct device - chan->dma_device->dev.

Also just spotted this left in your patch:
> +	if (!mxcmci_use_dma(host))
> +		return 0;
> +
>  	for_each_sg(data->sg, sg, data->sg_len, i) {
>  		if (sg->offset & 3 || sg->length & 3) {
> 			host->do_dma = 0;

Shouldn't this be a decision made by the DMA engine rather than the
driver?  Having looked at the MMCI code also doing this, I think this
should cause prep_slave_sg() to return NULL if it can't handle the
scatterlist.  On MMCI, we fall back to PIO if prep_slave_sg() returns
NULL.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] mxcmmc: use dmaengine API
  2011-01-12 10:09 ` [PATCH] mxcmmc: use " Sascha Hauer
  2011-01-12 10:26   ` Russell King - ARM Linux
@ 2011-01-12 12:25   ` Shawn Guo
  2011-01-12 12:33     ` Shawn Guo
  1 sibling, 1 reply; 6+ messages in thread
From: Shawn Guo @ 2011-01-12 12:25 UTC (permalink / raw)
  To: linux-arm-kernel

It seems all the tabs were turned into spaces.

On Wed, Jan 12, 2011 at 11:09:56AM +0100, Sascha Hauer wrote:
> This switches the mxcmmc driver to use the dmaengine API. Unlike
> the old one this one is always present in the tree, even if no DMA
> is implement, hence we can remove all the #ifdefs in from the driver.
> The driver automatically switches to PIO mode if no DMA support or no
> suitable channel is available.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/mmc/host/mxcmmc.c |  172 +++++++++++++++++++++++++--------------------
>  1 files changed, 97 insertions(+), 75 deletions(-)
> 
[...]

-- 
Regards,
Shawn

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] mxcmmc: use dmaengine API
  2011-01-12 12:25   ` Shawn Guo
@ 2011-01-12 12:33     ` Shawn Guo
  0 siblings, 0 replies; 6+ messages in thread
From: Shawn Guo @ 2011-01-12 12:33 UTC (permalink / raw)
  To: linux-arm-kernel

On Wed, Jan 12, 2011 at 8:25 PM, Shawn Guo <shawn.guo@freescale.com> wrote:
> It seems all the tabs were turned into spaces.
>
My problem.  Sorry for the noise.

> On Wed, Jan 12, 2011 at 11:09:56AM +0100, Sascha Hauer wrote:
>> This switches the mxcmmc driver to use the dmaengine API. Unlike
>> the old one this one is always present in the tree, even if no DMA
>> is implement, hence we can remove all the #ifdefs in from the driver.
>> The driver automatically switches to PIO mode if no DMA support or no
>> suitable channel is available.
>>
>> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
>> ---
>> ?drivers/mmc/host/mxcmmc.c | ?172 +++++++++++++++++++++++++--------------------
>> ?1 files changed, 97 insertions(+), 75 deletions(-)
>>
> [...]
>
> --
> Regards,
> Shawn
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>



-- 
Regards,
Shawn

^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH] mxcmmc: use dmaengine API
  2011-01-12 10:26   ` Russell King - ARM Linux
@ 2011-01-12 13:13     ` Sascha Hauer
  0 siblings, 0 replies; 6+ messages in thread
From: Sascha Hauer @ 2011-01-12 13:13 UTC (permalink / raw)
  To: linux-arm-kernel

On Wed, Jan 12, 2011 at 10:26:32AM +0000, Russell King - ARM Linux wrote:
> On Wed, Jan 12, 2011 at 11:09:56AM +0100, Sascha Hauer wrote:
> > +	host->dma_nents = dma_map_sg(mmc_dev(host->mmc), data->sg,
> > +				     data->sg_len,  host->dma_dir);
> 
> As recently discussed, you don't need to save dma_nents - the value to
> be passed to dma_unmap_sg() is data->sg_len, not host->dma_nents.
> 
> You should also do the map/unmap against the DMA engine device (which
> is the device actually doing DMA) rather than the peripheral (which is
> only the recipient of DMA).  The reason is - while the peripheral can
> see the DMA controller, the peripheral may be able to see all RAM but
> the DMA controller may have an IOMMU or limited view of RAM.

ok.

> 
> > +static int mxcmci_setup_dma(struct mmc_host *mmc)
> > +{
> > +	struct mxcmci_host *host = mmc_priv(mmc);
> > +	struct dma_slave_config *config = &host->dma_slave_config;
> > +
> > +	config->direction = DMA_FROM_DEVICE;
> 
> I would like to get some concensus on removing config->direction from
> the slave configuration entirely - and make all the fields below
> refer purely to the peripheral device parameters.  At the moment,
> the API allows them to be used ambiguously.

OK, I can remove this as it's unused by the dma driver anyway (and in
fact I wondered what purpose this field has while writing the dma
drivers)

> 
> > @@ -794,7 +823,7 @@ static int mxcmci_probe(struct platform_device *pdev)
> >  	mmc->max_blk_size = 2048;
> >  	mmc->max_blk_count = 65535;
> >  	mmc->max_req_size = mmc->max_blk_size * mmc->max_blk_count;
> > -	mmc->max_seg_size = mmc->max_req_size;
> > +	mmc->max_seg_size = 65535;
> 
> You can get this from the DMA parameters for the DMA engine device:
> 
> 	mmc->max_seg_size = dma_get_max_seg_size(dev);
> 
> where 'dev' is the DMA engine struct device - chan->dma_device->dev.

I prepared a patch to set the segment size in the i.MX DMA drivers.

> 
> Also just spotted this left in your patch:
> > +	if (!mxcmci_use_dma(host))
> > +		return 0;
> > +
> >  	for_each_sg(data->sg, sg, data->sg_len, i) {
> >  		if (sg->offset & 3 || sg->length & 3) {
> > 			host->do_dma = 0;
> 
> Shouldn't this be a decision made by the DMA engine rather than the
> driver?  Having looked at the MMCI code also doing this, I think this
> should cause prep_slave_sg() to return NULL if it can't handle the
> scatterlist.  On MMCI, we fall back to PIO if prep_slave_sg() returns
> NULL.

I prepared a patch which checks for invalid addresses and lengths in the
DMA drivers.

I'd like to push this patch like it is until the two points above are
solved upstream (with the other points fixed of course).

Sascha


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^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2011-01-12 13:13 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2011-01-12 10:09 let the mxcmmc driver use the dmaengine API Sascha Hauer
2011-01-12 10:09 ` [PATCH] mxcmmc: use " Sascha Hauer
2011-01-12 10:26   ` Russell King - ARM Linux
2011-01-12 13:13     ` Sascha Hauer
2011-01-12 12:25   ` Shawn Guo
2011-01-12 12:33     ` Shawn Guo

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