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mmc: atmel-mci: DMA can be used with other controller

PATCH New Hein Tibosch 2 participants 2 messages Aug 26, 2012 – Aug 28, 2012

Subsystems (3)
MMC, SD and SDIO Arm/Microchip (AT91) SoC support Microchip MMC/SD/SDIO mci driver
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Hein Tibosch

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#0 lore raw

PATCH 1/2 mmc: atmel-mci: DMA can be used with other controller

After the latest changes to atmel-mci, it could not be used with DMA on the AVR32 platform. This patch will allow to use DMA again and it will avoid access to MCI register ATMCI_DMA.

Signed-off-by Hein Tibosch <[email protected]>
---
 drivers/mmc/host/atmel-mci.c |   21 +++++++++------------
 1 files changed, 9 insertions(+), 12 deletions(-)
drivers/mmc/host/atmel-mci.c +9 -12
index f2c115e..66e9fdc 100644
@@ -71,7 +71,7 @@ enum atmci_pdc_buf {
 };
 
 struct atmel_mci_caps {
-	bool    has_dma;
+	bool    has_dma_conf_reg;
 	bool    has_pdc;
 	bool    has_cfg_reg;
 	bool    has_cstor_reg;

@@ -411,7 +411,7 @@ static int atmci_regs_show(struct seq_file *s, void *v)
 	atmci_show_status_reg(s, "SR", buf[ATMCI_SR / 4]);
 	atmci_show_status_reg(s, "IMR", buf[ATMCI_IMR / 4]);
 
-	if (host->caps.has_dma) {
+	if (host->caps.has_dma_conf_reg) {
 		u32 val;
 
 		val = buf[ATMCI_DMA / 4];

@@ -767,7 +767,7 @@ static void atmci_dma_complete(void *arg)
 
 	dev_vdbg(&host->pdev->dev, "DMA complete\n");
 
-	if (host->caps.has_dma)
+	if (host->caps.has_dma_conf_reg)
 		/* Disable DMA hardware handshaking on MCI */
 		atmci_writel(host, ATMCI_DMA, atmci_readl(host, ATMCI_DMA) & ~ATMCI_DMAEN);
 

@@ -954,7 +954,9 @@ atmci_prepare_data_dma(struct atmel_mci *host, struct mmc_data *data)
 		maxburst = atmci_convert_chksize(host->dma_conf.dst_maxburst);
 	}
 
-	atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(maxburst) | ATMCI_DMAEN);
+	if (host->caps.has_dma_conf_reg)
+		atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(maxburst) |
+			ATMCI_DMAEN);
 
 	sglen = dma_map_sg(chan->device->dev, data->sg,
 			data->sg_len, direction);

@@ -2202,7 +2204,7 @@ static void __init atmci_get_cap(struct atmel_mci *host)
 	dev_info(&host->pdev->dev,
 			"version: 0x%x\n", version);
 
-	host->caps.has_dma = 0;
+	host->caps.has_dma_conf_reg = 0;
 	host->caps.has_pdc = 1;
 	host->caps.has_cfg_reg = 0;
 	host->caps.has_cstor_reg = 0;

@@ -2219,12 +2221,7 @@ static void __init atmci_get_cap(struct atmel_mci *host)
 		host->caps.has_odd_clk_div = 1;
 	case 0x400:
 	case 0x300:
-#ifdef CONFIG_AT_HDMAC
-		host->caps.has_dma = 1;
-#else
-		dev_info(&host->pdev->dev,
-			"has dma capability but dma engine is not selected, then use pio\n");
-#endif
+		host->caps.has_dma_conf_reg = 1;
 		host->caps.has_pdc = 0;
 		host->caps.has_cfg_reg = 1;
 		host->caps.has_cstor_reg = 1;

@@ -2298,7 +2295,7 @@ static int __init atmci_probe(struct platform_device *pdev)
 
 	/* Get MCI capabilities and set operations according to it */
 	atmci_get_cap(host);
-	if (host->caps.has_dma && atmci_configure_dma(host)) {
+	if (atmci_configure_dma(host)) {
 		host->prepare_data = &atmci_prepare_data_dma;
 		host->submit_data = &atmci_submit_data_dma;
 		host->stop_transfer = &atmci_stop_transfer_dma;
Signature · 1 line
1.7.8.0
#1 lore raw

PATCH 1/2 mmc: atmel-mci: DMA can be used with other controller

Hi Hein,

Thanks for your investigation about the MCI issue with AVR chips.

Le 08/26/2012 10:20 PM, Hein Tibosch a ?crit :

Quoted 4 lines

After the latest changes to atmel-mci, it could not be used with DMA on the AVR32 platform. This patch will allow to use DMA again and it will avoid access to MCI register ATMCI_DMA.

I think you should add more details about the issue:
Even if the IP version is lower than v3xx and doesn't have the DMA configuration register, DMA transfers can be used with a different controller than the Atmel AHB DMA one. For instance, some AVR chips use the Synopsys DesignWare AHB DMA controller.

Quoted 2 lines
Signed-off-by Hein Tibosch <[email protected]>

Some comments below...

Quoted 71 lines
---
  drivers/mmc/host/atmel-mci.c |   21 +++++++++------------
  1 files changed, 9 insertions(+), 12 deletions(-)
drivers/mmc/host/atmel-mci.c +8 -11
index f2c115e..66e9fdc 100644
@@ -71,7 +71,7 @@ enum atmci_pdc_buf {
  };
 
  struct atmel_mci_caps {
-	bool    has_dma;
+	bool    has_dma_conf_reg;
  	bool    has_pdc;
  	bool    has_cfg_reg;
  	bool    has_cstor_reg;

@@ -411,7 +411,7 @@ static int atmci_regs_show(struct seq_file *s, void *v)
  	atmci_show_status_reg(s, "SR", buf[ATMCI_SR / 4]);
  	atmci_show_status_reg(s, "IMR", buf[ATMCI_IMR / 4]);
 
-	if (host->caps.has_dma) {
+	if (host->caps.has_dma_conf_reg) {
  		u32 val;
 
  		val = buf[ATMCI_DMA / 4];

@@ -767,7 +767,7 @@ static void atmci_dma_complete(void *arg)
 
  	dev_vdbg(&host->pdev->dev, "DMA complete\n");
 
-	if (host->caps.has_dma)
+	if (host->caps.has_dma_conf_reg)
  		/* Disable DMA hardware handshaking on MCI */
  		atmci_writel(host, ATMCI_DMA, atmci_readl(host, ATMCI_DMA) & ~ATMCI_DMAEN);
 

@@ -954,7 +954,9 @@ atmci_prepare_data_dma(struct atmel_mci *host, struct mmc_data *data)
  		maxburst = atmci_convert_chksize(host->dma_conf.dst_maxburst);
  	}
 
-	atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(maxburst) | ATMCI_DMAEN);
+	if (host->caps.has_dma_conf_reg)
+		atmci_writel(host, ATMCI_DMA, ATMCI_DMA_CHKSIZE(maxburst) |
+			ATMCI_DMAEN);
 
  	sglen = dma_map_sg(chan->device->dev, data->sg,
  			data->sg_len, direction);

@@ -2202,7 +2204,7 @@ static void __init atmci_get_cap(struct atmel_mci *host)
  	dev_info(&host->pdev->dev,
  			"version: 0x%x\n", version);
 
-	host->caps.has_dma = 0;
+	host->caps.has_dma_conf_reg = 0;
  	host->caps.has_pdc = 1;
  	host->caps.has_cfg_reg = 0;
  	host->caps.has_cstor_reg = 0;

@@ -2219,12 +2221,7 @@ static void __init atmci_get_cap(struct atmel_mci *host)
  		host->caps.has_odd_clk_div = 1;
  	case 0x400:
  	case 0x300:
-#ifdef CONFIG_AT_HDMAC
-		host->caps.has_dma = 1;
-#else
-		dev_info(&host->pdev->dev,
-			"has dma capability but dma engine is not selected, then use pio\n");
-#endif
+		host->caps.has_dma_conf_reg = 1;
  		host->caps.has_pdc = 0;
  		host->caps.has_cfg_reg = 1;
  		host->caps.has_cstor_reg = 1;

drivers/mmc/host/atmel-mci.c static int __init atmci_probe(struct platform_device *pdev) · line 2301

Quoted 8 lines
drivers/mmc/host/atmel-mci.c +1 -1
@@ -2298,7 +2295,7 @@ static int __init atmci_probe(struct platform_device *pdev)
 
  	/* Get MCI capabilities and set operations according to it */
  	atmci_get_cap(host);
-	if (host->caps.has_dma && atmci_configure_dma(host)) {
+	if (atmci_configure_dma(host)) {
  		host->prepare_data = &atmci_prepare_data_dma;
  		host->submit_data = &atmci_submit_data_dma;
  		host->stop_transfer = &atmci_stop_transfer_dma;

I have tested this patch on at91sam9m10g45, at91sam9g10 and at91sam9261. For chips without MCI support for Atmel AHB DMA, removing the host->caps.has_dma test involves to use pdata->dma_slave with more caution to avoid some NULL pointer dereferences

@@ -2168,16 +2168,21 @@ static bool atmci_configure_dma(struct atmel_mci *host)

                 return false;

         pdata = host->pdev->dev.platform_data;

+ if (!pdata)
+ return false;

- if (pdata && find_slave_dev(pdata->dma_slave)) {

+       if (pdata->dma_slave && find_slave_dev(pdata->dma_slave)) {
                 dma_cap_mask_t mask;

Regards

Ludovic