[PATCH v4 0/3] solve SDHCI DWC MSHC 128MB DMA boundary limitation

[PATCH v4 0/3] solve SDHCI DWC MSHC 128MB DMA boundary limitation

[Jisheng Zhang]

When using DMA, if the DMA addr spans 128MB boundary, we have to split
the DMA transfer into two so that each one doesn't exceed the boundary.

patch1 adds adma_table_num to struct sdhci_host so that driver can
control the ADMA table number.
patch2 introduces adma_write_desc() hook to struct sdhci_ops so that
driver can override it.
patch3 finally solves the 128MB boundary limitation.

since v3:
  - s/adma_table_num/adma_table_cnt
  - add comment to adma_table_cnt
  - make the exported function name without the _
  - let sdhci_adma_write_desc() accept &desc param and set the new desc
    value

since v2:
  - make use of "likely" to check (!len || BOUNDARY_OK(addr, len))
  - explictly include <linux/sizes.h> for SZ_128M

since v1:
  - fix BOUNDARY_OK macro if addr+len is aligned to 128MB
  - use DIV_ROUND_UP to cal extra desc num
  - fix !len for dwcmshc_adma_write_desc()

Jisheng Zhang (3):
  mmc: sdhci: add adma_table_cnt member to struct sdhci_host
  mmc: sdhci: introduce adma_write_desc() hook to struct sdhci_ops
  mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation

 drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +++++++++++++++++++++
 drivers/mmc/host/sdhci.c            | 54 +++++++++++++++++------------
 drivers/mmc/host/sdhci.h            |  7 ++++
 3 files changed, 78 insertions(+), 22 deletions(-)

-- 
2.18.0

[PATCH v4 1/3] mmc: sdhci: add adma_table_cnt member to struct sdhci_host

[Jisheng Zhang]

This patch adds adma_table_cnt member to struct sdhci_host to give more
flexibility to drivers to control the ADMA table count.

Default value of adma_table_cnt is set to (SDHCI_MAX_SEGS * 2 + 1).

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
 drivers/mmc/host/sdhci.c | 17 +++++++++--------
 drivers/mmc/host/sdhci.h |  3 +++
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 1b3fbd9bd5c5..52ccf4644384 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -3322,6 +3322,13 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
 
 	host->sdma_boundary = SDHCI_DEFAULT_BOUNDARY_ARG;
 
+	/*
+	 * The DMA table descriptor count is calculated as the maximum
+	 * number of segments times 2, to allow for an alignment
+	 * descriptor for each segment, plus 1 for a nop end descriptor.
+	 */
+	host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1;
+
 	return host;
 }
 
@@ -3567,18 +3574,12 @@ int sdhci_setup_host(struct sdhci_host *host)
 		dma_addr_t dma;
 		void *buf;
 
-		/*
-		 * The DMA descriptor table size is calculated as the maximum
-		 * number of segments times 2, to allow for an alignment
-		 * descriptor for each segment, plus 1 for a nop end descriptor,
-		 * all multipled by the descriptor size.
-		 */
 		if (host->flags & SDHCI_USE_64_BIT_DMA) {
-			host->adma_table_sz = (SDHCI_MAX_SEGS * 2 + 1) *
+			host->adma_table_sz = host->adma_table_cnt *
 					      SDHCI_ADMA2_64_DESC_SZ;
 			host->desc_sz = SDHCI_ADMA2_64_DESC_SZ;
 		} else {
-			host->adma_table_sz = (SDHCI_MAX_SEGS * 2 + 1) *
+			host->adma_table_sz = host->adma_table_cnt *
 					      SDHCI_ADMA2_32_DESC_SZ;
 			host->desc_sz = SDHCI_ADMA2_32_DESC_SZ;
 		}
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index f0bd36ce3817..25bddd21de31 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -563,6 +563,9 @@ struct sdhci_host {
 	/* Host SDMA buffer boundary. */
 	u32			sdma_boundary;
 
+	/* Host ADMA table count */
+	u32			adma_table_cnt;
+
 	u64			data_timeout;
 
 	unsigned long private[0] ____cacheline_aligned;
-- 
2.18.0

[PATCH v4 1/3] mmc: sdhci: add adma_table_cnt member to struct sdhci_host

[Adrian Hunter]

On 23/08/18 13:07, Jisheng Zhang wrote:
> This patch adds adma_table_cnt member to struct sdhci_host to give more
> flexibility to drivers to control the ADMA table count.
> 
> Default value of adma_table_cnt is set to (SDHCI_MAX_SEGS * 2 + 1).
> 
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  drivers/mmc/host/sdhci.c | 17 +++++++++--------
>  drivers/mmc/host/sdhci.h |  3 +++
>  2 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 1b3fbd9bd5c5..52ccf4644384 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -3322,6 +3322,13 @@ struct sdhci_host *sdhci_alloc_host(struct device *dev,
>  
>  	host->sdma_boundary = SDHCI_DEFAULT_BOUNDARY_ARG;
>  
> +	/*
> +	 * The DMA table descriptor count is calculated as the maximum
> +	 * number of segments times 2, to allow for an alignment
> +	 * descriptor for each segment, plus 1 for a nop end descriptor.
> +	 */
> +	host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1;
> +
>  	return host;
>  }
>  
> @@ -3567,18 +3574,12 @@ int sdhci_setup_host(struct sdhci_host *host)
>  		dma_addr_t dma;
>  		void *buf;
>  
> -		/*
> -		 * The DMA descriptor table size is calculated as the maximum
> -		 * number of segments times 2, to allow for an alignment
> -		 * descriptor for each segment, plus 1 for a nop end descriptor,
> -		 * all multipled by the descriptor size.
> -		 */
>  		if (host->flags & SDHCI_USE_64_BIT_DMA) {
> -			host->adma_table_sz = (SDHCI_MAX_SEGS * 2 + 1) *
> +			host->adma_table_sz = host->adma_table_cnt *
>  					      SDHCI_ADMA2_64_DESC_SZ;
>  			host->desc_sz = SDHCI_ADMA2_64_DESC_SZ;
>  		} else {
> -			host->adma_table_sz = (SDHCI_MAX_SEGS * 2 + 1) *
> +			host->adma_table_sz = host->adma_table_cnt *
>  					      SDHCI_ADMA2_32_DESC_SZ;
>  			host->desc_sz = SDHCI_ADMA2_32_DESC_SZ;
>  		}
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index f0bd36ce3817..25bddd21de31 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -563,6 +563,9 @@ struct sdhci_host {
>  	/* Host SDMA buffer boundary. */
>  	u32			sdma_boundary;
>  
> +	/* Host ADMA table count */
> +	u32			adma_table_cnt;
> +
>  	u64			data_timeout;
>  
>  	unsigned long private[0] ____cacheline_aligned;
> 

[PATCH v4 2/3] mmc: sdhci: introduce adma_write_desc() hook to struct sdhci_ops

[Jisheng Zhang]

Add this hook so that it can be overridden with driver specific
implementations. We also let the original sdhci_adma_write_desc()
accept &desc so that the function can set its new value. Then export
the function so that it could be reused by driver's specific
implementations.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
 drivers/mmc/host/sdhci.c | 37 +++++++++++++++++++++++--------------
 drivers/mmc/host/sdhci.h |  4 ++++
 2 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 52ccf4644384..eb21d2db7f05 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -554,10 +554,10 @@ static void sdhci_kunmap_atomic(void *buffer, unsigned long *flags)
 	local_irq_restore(*flags);
 }
 
-static void sdhci_adma_write_desc(struct sdhci_host *host, void *desc,
-				  dma_addr_t addr, int len, unsigned cmd)
+void sdhci_adma_write_desc(struct sdhci_host *host, void **desc,
+			   dma_addr_t addr, int len, unsigned int cmd)
 {
-	struct sdhci_adma2_64_desc *dma_desc = desc;
+	struct sdhci_adma2_64_desc *dma_desc = *desc;
 
 	/* 32-bit and 64-bit descriptors have these members in same position */
 	dma_desc->cmd = cpu_to_le16(cmd);
@@ -566,6 +566,19 @@ static void sdhci_adma_write_desc(struct sdhci_host *host, void *desc,
 
 	if (host->flags & SDHCI_USE_64_BIT_DMA)
 		dma_desc->addr_hi = cpu_to_le32((u64)addr >> 32);
+
+	*desc += host->desc_sz;
+}
+EXPORT_SYMBOL_GPL(sdhci_adma_write_desc);
+
+static inline void __sdhci_adma_write_desc(struct sdhci_host *host,
+					   void **desc, dma_addr_t addr,
+					   int len, unsigned int cmd)
+{
+	if (host->ops->adma_write_desc)
+		host->ops->adma_write_desc(host, desc, addr, len, cmd);
+
+	sdhci_adma_write_desc(host, desc, addr, len, cmd);
 }
 
 static void sdhci_adma_mark_end(void *desc)
@@ -618,28 +631,24 @@ static void sdhci_adma_table_pre(struct sdhci_host *host,
 			}
 
 			/* tran, valid */
-			sdhci_adma_write_desc(host, desc, align_addr, offset,
-					      ADMA2_TRAN_VALID);
+			__sdhci_adma_write_desc(host, &desc, align_addr,
+						offset, ADMA2_TRAN_VALID);
 
 			BUG_ON(offset > 65536);
 
 			align += SDHCI_ADMA2_ALIGN;
 			align_addr += SDHCI_ADMA2_ALIGN;
 
-			desc += host->desc_sz;
-
 			addr += offset;
 			len -= offset;
 		}
 
 		BUG_ON(len > 65536);
 
-		if (len) {
-			/* tran, valid */
-			sdhci_adma_write_desc(host, desc, addr, len,
-					      ADMA2_TRAN_VALID);
-			desc += host->desc_sz;
-		}
+		/* tran, valid */
+		if (len)
+			__sdhci_adma_write_desc(host, &desc, addr, len,
+						ADMA2_TRAN_VALID);
 
 		/*
 		 * If this triggers then we have a calculation bug
@@ -656,7 +665,7 @@ static void sdhci_adma_table_pre(struct sdhci_host *host,
 		}
 	} else {
 		/* Add a terminating entry - nop, end, valid */
-		sdhci_adma_write_desc(host, desc, 0, 0, ADMA2_NOP_END_VALID);
+		__sdhci_adma_write_desc(host, &desc, 0, 0, ADMA2_NOP_END_VALID);
 	}
 }
 
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 25bddd21de31..2115416f973a 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -606,6 +606,8 @@ struct sdhci_ops {
 	void    (*adma_workaround)(struct sdhci_host *host, u32 intmask);
 	void    (*card_event)(struct sdhci_host *host);
 	void	(*voltage_switch)(struct sdhci_host *host);
+	void	(*adma_write_desc)(struct sdhci_host *host, void **desc,
+				   dma_addr_t addr, int len, unsigned int cmd);
 };
 
 #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
@@ -736,6 +738,8 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios);
 int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
 				      struct mmc_ios *ios);
 void sdhci_enable_sdio_irq(struct mmc_host *mmc, int enable);
+void sdhci_adma_write_desc(struct sdhci_host *host, void **desc,
+			   dma_addr_t addr, int len, unsigned int cmd);
 
 #ifdef CONFIG_PM
 int sdhci_suspend_host(struct sdhci_host *host);
-- 
2.18.0

[PATCH v4 2/3] mmc: sdhci: introduce adma_write_desc() hook to struct sdhci_ops

[Adrian Hunter]

On 23/08/18 13:08, Jisheng Zhang wrote:
> Add this hook so that it can be overridden with driver specific
> implementations. We also let the original sdhci_adma_write_desc()
> accept &desc so that the function can set its new value. Then export
> the function so that it could be reused by driver's specific
> implementations.
> 
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

> ---
>  drivers/mmc/host/sdhci.c | 37 +++++++++++++++++++++++--------------
>  drivers/mmc/host/sdhci.h |  4 ++++
>  2 files changed, 27 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 52ccf4644384..eb21d2db7f05 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -554,10 +554,10 @@ static void sdhci_kunmap_atomic(void *buffer, unsigned long *flags)
>  	local_irq_restore(*flags);
>  }
>  
> -static void sdhci_adma_write_desc(struct sdhci_host *host, void *desc,
> -				  dma_addr_t addr, int len, unsigned cmd)
> +void sdhci_adma_write_desc(struct sdhci_host *host, void **desc,
> +			   dma_addr_t addr, int len, unsigned int cmd)
>  {
> -	struct sdhci_adma2_64_desc *dma_desc = desc;
> +	struct sdhci_adma2_64_desc *dma_desc = *desc;
>  
>  	/* 32-bit and 64-bit descriptors have these members in same position */
>  	dma_desc->cmd = cpu_to_le16(cmd);
> @@ -566,6 +566,19 @@ static void sdhci_adma_write_desc(struct sdhci_host *host, void *desc,
>  
>  	if (host->flags & SDHCI_USE_64_BIT_DMA)
>  		dma_desc->addr_hi = cpu_to_le32((u64)addr >> 32);
> +
> +	*desc += host->desc_sz;
> +}
> +EXPORT_SYMBOL_GPL(sdhci_adma_write_desc);
> +
> +static inline void __sdhci_adma_write_desc(struct sdhci_host *host,
> +					   void **desc, dma_addr_t addr,
> +					   int len, unsigned int cmd)
> +{
> +	if (host->ops->adma_write_desc)
> +		host->ops->adma_write_desc(host, desc, addr, len, cmd);
> +
> +	sdhci_adma_write_desc(host, desc, addr, len, cmd);
>  }
>  
>  static void sdhci_adma_mark_end(void *desc)
> @@ -618,28 +631,24 @@ static void sdhci_adma_table_pre(struct sdhci_host *host,
>  			}
>  
>  			/* tran, valid */
> -			sdhci_adma_write_desc(host, desc, align_addr, offset,
> -					      ADMA2_TRAN_VALID);
> +			__sdhci_adma_write_desc(host, &desc, align_addr,
> +						offset, ADMA2_TRAN_VALID);
>  
>  			BUG_ON(offset > 65536);
>  
>  			align += SDHCI_ADMA2_ALIGN;
>  			align_addr += SDHCI_ADMA2_ALIGN;
>  
> -			desc += host->desc_sz;
> -
>  			addr += offset;
>  			len -= offset;
>  		}
>  
>  		BUG_ON(len > 65536);
>  
> -		if (len) {
> -			/* tran, valid */
> -			sdhci_adma_write_desc(host, desc, addr, len,
> -					      ADMA2_TRAN_VALID);
> -			desc += host->desc_sz;
> -		}
> +		/* tran, valid */
> +		if (len)
> +			__sdhci_adma_write_desc(host, &desc, addr, len,
> +						ADMA2_TRAN_VALID);
>  
>  		/*
>  		 * If this triggers then we have a calculation bug
> @@ -656,7 +665,7 @@ static void sdhci_adma_table_pre(struct sdhci_host *host,
>  		}
>  	} else {
>  		/* Add a terminating entry - nop, end, valid */
> -		sdhci_adma_write_desc(host, desc, 0, 0, ADMA2_NOP_END_VALID);
> +		__sdhci_adma_write_desc(host, &desc, 0, 0, ADMA2_NOP_END_VALID);
>  	}
>  }
>  
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 25bddd21de31..2115416f973a 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -606,6 +606,8 @@ struct sdhci_ops {
>  	void    (*adma_workaround)(struct sdhci_host *host, u32 intmask);
>  	void    (*card_event)(struct sdhci_host *host);
>  	void	(*voltage_switch)(struct sdhci_host *host);
> +	void	(*adma_write_desc)(struct sdhci_host *host, void **desc,
> +				   dma_addr_t addr, int len, unsigned int cmd);
>  };
>  
>  #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> @@ -736,6 +738,8 @@ void sdhci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios);
>  int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
>  				      struct mmc_ios *ios);
>  void sdhci_enable_sdio_irq(struct mmc_host *mmc, int enable);
> +void sdhci_adma_write_desc(struct sdhci_host *host, void **desc,
> +			   dma_addr_t addr, int len, unsigned int cmd);
>  
>  #ifdef CONFIG_PM
>  int sdhci_suspend_host(struct sdhci_host *host);
> 

[PATCH v4 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation

[Jisheng Zhang]

When using DMA, if the DMA addr spans 128MB boundary, we have to split
the DMA transfer into two so that each one doesn't exceed the boundary.

Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
---
 drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
index 1b7cd144fb01..df0a3aeabe19 100644
--- a/drivers/mmc/host/sdhci-of-dwcmshc.c
+++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
@@ -8,21 +8,48 @@
  */
 
 #include <linux/clk.h>
+#include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/sizes.h>
 
 #include "sdhci-pltfm.h"
 
+#define BOUNDARY_OK(addr, len) \
+	((addr | (SZ_128M - 1)) == ((addr + len - 1) | (SZ_128M - 1)))
+
 struct dwcmshc_priv {
 	struct clk	*bus_clk;
 };
 
+/*
+ * If DMA addr spans 128MB boundary, we split the DMA transfer into two
+ * so that the DMA transfer doesn't exceed the boundary.
+ */
+static void dwcmshc_adma_write_desc(struct sdhci_host *host, void **desc,
+				    dma_addr_t addr, int len, unsigned int cmd)
+{
+	int tmplen, offset;
+
+	if (likely(!len || BOUNDARY_OK(addr, len)))
+		sdhci_adma_write_desc(host, desc, addr, len, cmd);
+
+	offset = addr & (SZ_128M - 1);
+	tmplen = SZ_128M - offset;
+	sdhci_adma_write_desc(host, desc, addr, tmplen, cmd);
+
+	addr += tmplen;
+	len -= tmplen;
+	sdhci_adma_write_desc(host, desc, addr, len, cmd);
+}
+
 static const struct sdhci_ops sdhci_dwcmshc_ops = {
 	.set_clock		= sdhci_set_clock,
 	.set_bus_width		= sdhci_set_bus_width,
 	.set_uhs_signaling	= sdhci_set_uhs_signaling,
 	.get_max_clock		= sdhci_pltfm_clk_get_max_clock,
 	.reset			= sdhci_reset,
+	.adma_write_desc	= dwcmshc_adma_write_desc,
 };
 
 static const struct sdhci_pltfm_data sdhci_dwcmshc_pdata = {
@@ -36,12 +63,24 @@ static int dwcmshc_probe(struct platform_device *pdev)
 	struct sdhci_host *host;
 	struct dwcmshc_priv *priv;
 	int err;
+	u32 extra;
 
 	host = sdhci_pltfm_init(pdev, &sdhci_dwcmshc_pdata,
 				sizeof(struct dwcmshc_priv));
 	if (IS_ERR(host))
 		return PTR_ERR(host);
 
+	/*
+	 * The DMA table descriptor count is calculated as the maximum
+	 * number of segments times 2, to allow for an alignment
+	 * descriptor for each segment, plus 1 for a nop end descriptor,
+	 * plus extra number for cross 128M boundary handling.
+	 */
+	extra = DIV_ROUND_UP(totalram_pages, SZ_128M / PAGE_SIZE);
+	if (extra > SDHCI_MAX_SEGS)
+		extra = SDHCI_MAX_SEGS;
+	host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1 + extra;
+
 	pltfm_host = sdhci_priv(host);
 	priv = sdhci_pltfm_priv(pltfm_host);
 
-- 
2.18.0

[PATCH v4 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation

[Adrian Hunter]

On 23/08/18 13:09, Jisheng Zhang wrote:
> When using DMA, if the DMA addr spans 128MB boundary, we have to split
> the DMA transfer into two so that each one doesn't exceed the boundary.
> 
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> ---
>  drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> index 1b7cd144fb01..df0a3aeabe19 100644
> --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> @@ -8,21 +8,48 @@
>   */
>  
>  #include <linux/clk.h>
> +#include <linux/mm.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/sizes.h>
>  
>  #include "sdhci-pltfm.h"
>  
> +#define BOUNDARY_OK(addr, len) \
> +	((addr | (SZ_128M - 1)) == ((addr + len - 1) | (SZ_128M - 1)))
> +
>  struct dwcmshc_priv {
>  	struct clk	*bus_clk;
>  };
>  
> +/*
> + * If DMA addr spans 128MB boundary, we split the DMA transfer into two
> + * so that the DMA transfer doesn't exceed the boundary.
> + */
> +static void dwcmshc_adma_write_desc(struct sdhci_host *host, void **desc,
> +				    dma_addr_t addr, int len, unsigned int cmd)
> +{
> +	int tmplen, offset;
> +
> +	if (likely(!len || BOUNDARY_OK(addr, len)))
> +		sdhci_adma_write_desc(host, desc, addr, len, cmd);

Doesn't this need a return? i.e.

		return;
	}

> +
> +	offset = addr & (SZ_128M - 1);
> +	tmplen = SZ_128M - offset;
> +	sdhci_adma_write_desc(host, desc, addr, tmplen, cmd);
> +
> +	addr += tmplen;
> +	len -= tmplen;
> +	sdhci_adma_write_desc(host, desc, addr, len, cmd);
> +}
> +
>  static const struct sdhci_ops sdhci_dwcmshc_ops = {
>  	.set_clock		= sdhci_set_clock,
>  	.set_bus_width		= sdhci_set_bus_width,
>  	.set_uhs_signaling	= sdhci_set_uhs_signaling,
>  	.get_max_clock		= sdhci_pltfm_clk_get_max_clock,
>  	.reset			= sdhci_reset,
> +	.adma_write_desc	= dwcmshc_adma_write_desc,
>  };
>  
>  static const struct sdhci_pltfm_data sdhci_dwcmshc_pdata = {
> @@ -36,12 +63,24 @@ static int dwcmshc_probe(struct platform_device *pdev)
>  	struct sdhci_host *host;
>  	struct dwcmshc_priv *priv;
>  	int err;
> +	u32 extra;
>  
>  	host = sdhci_pltfm_init(pdev, &sdhci_dwcmshc_pdata,
>  				sizeof(struct dwcmshc_priv));
>  	if (IS_ERR(host))
>  		return PTR_ERR(host);
>  
> +	/*
> +	 * The DMA table descriptor count is calculated as the maximum
> +	 * number of segments times 2, to allow for an alignment
> +	 * descriptor for each segment, plus 1 for a nop end descriptor,
> +	 * plus extra number for cross 128M boundary handling.
> +	 */
> +	extra = DIV_ROUND_UP(totalram_pages, SZ_128M / PAGE_SIZE);

You are assuming here that totalram_pages gives you the highest physical
page number.  Is that true?

> +	if (extra > SDHCI_MAX_SEGS)
> +		extra = SDHCI_MAX_SEGS;
> +	host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1 + extra;

That should be:

	host->adma_table_cnt += extra;

> +
>  	pltfm_host = sdhci_priv(host);
>  	priv = sdhci_pltfm_priv(pltfm_host);
>  
> 

[PATCH v4 3/3] mmc: sdhci-of-dwcmshc: solve 128MB DMA boundary limitation

[Jisheng Zhang]

On Thu, 23 Aug 2018 14:51:26 +0300 Adrian Hunter wrote:

> On 23/08/18 13:09, Jisheng Zhang wrote:
> > When using DMA, if the DMA addr spans 128MB boundary, we have to split
> > the DMA transfer into two so that each one doesn't exceed the boundary.
> > 
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> > ---
> >  drivers/mmc/host/sdhci-of-dwcmshc.c | 39 +++++++++++++++++++++++++++++
> >  1 file changed, 39 insertions(+)
> > 
> > diff --git a/drivers/mmc/host/sdhci-of-dwcmshc.c b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > index 1b7cd144fb01..df0a3aeabe19 100644
> > --- a/drivers/mmc/host/sdhci-of-dwcmshc.c
> > +++ b/drivers/mmc/host/sdhci-of-dwcmshc.c
> > @@ -8,21 +8,48 @@
> >   */
> >  
> >  #include <linux/clk.h>
> > +#include <linux/mm.h>
> >  #include <linux/module.h>
> >  #include <linux/of.h>
> > +#include <linux/sizes.h>
> >  
> >  #include "sdhci-pltfm.h"
> >  
> > +#define BOUNDARY_OK(addr, len) \
> > +	((addr | (SZ_128M - 1)) == ((addr + len - 1) | (SZ_128M - 1)))
> > +
> >  struct dwcmshc_priv {
> >  	struct clk	*bus_clk;
> >  };
> >  
> > +/*
> > + * If DMA addr spans 128MB boundary, we split the DMA transfer into two
> > + * so that the DMA transfer doesn't exceed the boundary.
> > + */
> > +static void dwcmshc_adma_write_desc(struct sdhci_host *host, void **desc,
> > +				    dma_addr_t addr, int len, unsigned int cmd)
> > +{
> > +	int tmplen, offset;
> > +
> > +	if (likely(!len || BOUNDARY_OK(addr, len)))
> > +		sdhci_adma_write_desc(host, desc, addr, len, cmd);  
> 
> Doesn't this need a return? i.e.
> 
> 		return;

oops, I made a mistake here. Pre v4, there's a return...
Thanks so much.


> 	}
> 
> > +
> > +	offset = addr & (SZ_128M - 1);
> > +	tmplen = SZ_128M - offset;
> > +	sdhci_adma_write_desc(host, desc, addr, tmplen, cmd);
> > +
> > +	addr += tmplen;
> > +	len -= tmplen;
> > +	sdhci_adma_write_desc(host, desc, addr, len, cmd);
> > +}
> > +
> >  static const struct sdhci_ops sdhci_dwcmshc_ops = {
> >  	.set_clock		= sdhci_set_clock,
> >  	.set_bus_width		= sdhci_set_bus_width,
> >  	.set_uhs_signaling	= sdhci_set_uhs_signaling,
> >  	.get_max_clock		= sdhci_pltfm_clk_get_max_clock,
> >  	.reset			= sdhci_reset,
> > +	.adma_write_desc	= dwcmshc_adma_write_desc,
> >  };
> >  
> >  static const struct sdhci_pltfm_data sdhci_dwcmshc_pdata = {
> > @@ -36,12 +63,24 @@ static int dwcmshc_probe(struct platform_device *pdev)
> >  	struct sdhci_host *host;
> >  	struct dwcmshc_priv *priv;
> >  	int err;
> > +	u32 extra;
> >  
> >  	host = sdhci_pltfm_init(pdev, &sdhci_dwcmshc_pdata,
> >  				sizeof(struct dwcmshc_priv));
> >  	if (IS_ERR(host))
> >  		return PTR_ERR(host);
> >  
> > +	/*
> > +	 * The DMA table descriptor count is calculated as the maximum
> > +	 * number of segments times 2, to allow for an alignment
> > +	 * descriptor for each segment, plus 1 for a nop end descriptor,
> > +	 * plus extra number for cross 128M boundary handling.
> > +	 */
> > +	extra = DIV_ROUND_UP(totalram_pages, SZ_128M / PAGE_SIZE);  
> 
> You are assuming here that totalram_pages gives you the highest physical
> page number.  Is that true?

Per my understanding, it's true. What I need is the MemTotal/PAGE_SIZE where
Memtotal is from /proc/meminfo. After reading the code, I found this is
totalram_pages as shown in si_meminfo()

> 
> > +	if (extra > SDHCI_MAX_SEGS)
> > +		extra = SDHCI_MAX_SEGS;
> > +	host->adma_table_cnt = SDHCI_MAX_SEGS * 2 + 1 + extra;  
> 
> That should be:
> 
> 	host->adma_table_cnt += extra;

yep, will do in v5

> 
> > +
> >  	pltfm_host = sdhci_priv(host);
> >  	priv = sdhci_pltfm_priv(pltfm_host);
> >  
> >   
>