[PATCH] of: calculate masks of the device based on dma-range size

[PATCH] of: calculate masks of the device based on dma-range size

[Murali Karicheri]

This patch update of_dma_configure() API to calculate the
masks (dma_mask and coherent_dma_mask) based on the dma-range
values set in DT for the device. Also limit the mask to lower
of the default mask and mask calculated.

Cc: Joerg Roedel <joro@8bytes.org>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
---
 drivers/of/device.c |   27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/drivers/of/device.c b/drivers/of/device.c
index 314c8a9..44209fa 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -83,17 +83,18 @@ int of_device_add(struct platform_device *ofdev)
  */
 void of_dma_configure(struct device *dev, struct device_node *np)
 {
-	u64 dma_addr, paddr, size;
+	u64 dma_addr = 0, paddr, size;
 	int ret;
 	bool coherent;
-	unsigned long offset;
+	unsigned long offset = 0;
 	struct iommu_ops *iommu;
 
 	/*
 	 * Set default dma-mask to 32 bit. Drivers are expected to setup
 	 * the correct supported dma_mask.
 	 */
-	dev->coherent_dma_mask = DMA_BIT_MASK(32);
+	if (!dev->coherent_dma_mask)
+		dev->coherent_dma_mask = DMA_BIT_MASK(32);
 
 	/*
 	 * Set it to coherent_dma_mask by default if the architecture
@@ -102,11 +103,14 @@ void of_dma_configure(struct device *dev, struct device_node *np)
 	if (!dev->dma_mask)
 		dev->dma_mask = &dev->coherent_dma_mask;
 
+	/*
+	 * Set default size to cover the 32-bit. Drivers are expected to setup
+	 * the correct size and dma_mask.
+	 */
+	size = 1ULL << 32;
+
 	ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
-	if (ret < 0) {
-		dma_addr = offset = 0;
-		size = dev->coherent_dma_mask + 1;
-	} else {
+	if (!ret) {
 		offset = PFN_DOWN(paddr - dma_addr);
 
 		/*
@@ -128,6 +132,15 @@ void of_dma_configure(struct device *dev, struct device_node *np)
 
 	dev->dma_pfn_offset = offset;
 
+	/*
+	 * Limit coherent and dma mask based on size and default mask
+	 * set by the driver.
+	 */
+	dev->coherent_dma_mask = min(dev->coherent_dma_mask,
+				     DMA_BIT_MASK(ilog2(dma_addr + size)));
+	*dev->dma_mask = min((*dev->dma_mask),
+			     DMA_BIT_MASK(ilog2(dma_addr + size)));
+
 	coherent = of_dma_is_coherent(np);
 	dev_dbg(dev, "device is%sdma coherent\n",
 		coherent ? " " : " not ");
-- 
1.7.9.5

[PATCH] of: calculate masks of the device based on dma-range size

[Catalin Marinas]

On Fri, Feb 06, 2015 at 03:15:20PM -0500, Murali Karicheri wrote:
> diff --git a/drivers/of/device.c b/drivers/of/device.c
> index 314c8a9..44209fa 100644
> --- a/drivers/of/device.c
> +++ b/drivers/of/device.c
> @@ -83,17 +83,18 @@ int of_device_add(struct platform_device *ofdev)
>   */
>  void of_dma_configure(struct device *dev, struct device_node *np)
>  {
> -	u64 dma_addr, paddr, size;
> +	u64 dma_addr = 0, paddr, size;
>  	int ret;
>  	bool coherent;
> -	unsigned long offset;
> +	unsigned long offset = 0;
>  	struct iommu_ops *iommu;
>  
>  	/*
>  	 * Set default dma-mask to 32 bit. Drivers are expected to setup
>  	 * the correct supported dma_mask.
>  	 */
> -	dev->coherent_dma_mask = DMA_BIT_MASK(32);
> +	if (!dev->coherent_dma_mask)
> +		dev->coherent_dma_mask = DMA_BIT_MASK(32);
>  
>  	/*
>  	 * Set it to coherent_dma_mask by default if the architecture
> @@ -102,11 +103,14 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>  	if (!dev->dma_mask)
>  		dev->dma_mask = &dev->coherent_dma_mask;
>  
> +	/*
> +	 * Set default size to cover the 32-bit. Drivers are expected to setup
> +	 * the correct size and dma_mask.
> +	 */

Nitpick: drivers don't set up the size, just the mask. We read the size
from DT.

> +	size = 1ULL << 32;
> +
>  	ret = of_dma_get_range(np, &dma_addr, &paddr, &size);
> -	if (ret < 0) {
> -		dma_addr = offset = 0;
> -		size = dev->coherent_dma_mask + 1;

Do you assume that, on error, of_dma_get_range() does not touch any of
the dma_addr/paddr/size? It looks safer to me to leave it as the
original.

> -	} else {
> +	if (!ret) {
>  		offset = PFN_DOWN(paddr - dma_addr);
>  
>  		/*
> @@ -128,6 +132,15 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>  
>  	dev->dma_pfn_offset = offset;
>  
> +	/*
> +	 * Limit coherent and dma mask based on size and default mask
> +	 * set by the driver.
> +	 */
> +	dev->coherent_dma_mask = min(dev->coherent_dma_mask,
> +				     DMA_BIT_MASK(ilog2(dma_addr + size)));

Do we need to cover the case where size is incorrectly set to 0 in the
DT? At least some warning and leaving the mask unchanged.

> +	*dev->dma_mask = min((*dev->dma_mask),
> +			     DMA_BIT_MASK(ilog2(dma_addr + size)));
> +
>  	coherent = of_dma_is_coherent(np);
>  	dev_dbg(dev, "device is%sdma coherent\n",
>  		coherent ? " " : " not ");

-- 
Catalin

[PATCH] of: calculate masks of the device based on dma-range size

[Murali Karicheri]

On 02/09/2015 06:27 AM, Catalin Marinas wrote:
> On Fri, Feb 06, 2015 at 03:15:20PM -0500, Murali Karicheri wrote:
>> diff --git a/drivers/of/device.c b/drivers/of/device.c
>> index 314c8a9..44209fa 100644
>> --- a/drivers/of/device.c
>> +++ b/drivers/of/device.c
>> @@ -83,17 +83,18 @@ int of_device_add(struct platform_device *ofdev)
>>    */
>>   void of_dma_configure(struct device *dev, struct device_node *np)
>>   {
>> -	u64 dma_addr, paddr, size;
>> +	u64 dma_addr = 0, paddr, size;
>>   	int ret;
>>   	bool coherent;
>> -	unsigned long offset;
>> +	unsigned long offset = 0;
>>   	struct iommu_ops *iommu;
>>
>>   	/*
>>   	 * Set default dma-mask to 32 bit. Drivers are expected to setup
>>   	 * the correct supported dma_mask.
>>   	 */
>> -	dev->coherent_dma_mask = DMA_BIT_MASK(32);
>> +	if (!dev->coherent_dma_mask)
>> +		dev->coherent_dma_mask = DMA_BIT_MASK(32);
>>
>>   	/*
>>   	 * Set it to coherent_dma_mask by default if the architecture
>> @@ -102,11 +103,14 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>>   	if (!dev->dma_mask)
>>   		dev->dma_mask =&dev->coherent_dma_mask;
>>
>> +	/*
>> +	 * Set default size to cover the 32-bit. Drivers are expected to setup
>> +	 * the correct size and dma_mask.
>> +	 */
>
> Nitpick: drivers don't set up the size, just the mask. We read the size
> from DT.

Not sure how this came, I will update this.
>
>> +	size = 1ULL<<  32;
>> +
>>   	ret = of_dma_get_range(np,&dma_addr,&paddr,&size);
>> -	if (ret<  0) {
>> -		dma_addr = offset = 0;
>> -		size = dev->coherent_dma_mask + 1;
>
> Do you assume that, on error, of_dma_get_range() does not touch any of
> the dma_addr/paddr/size? It looks safer to me to leave it as the
> original.
I think dma_addr and paddr is both modified on error. So this change 
can't be done. I will revert the logic back to original.
>
>> -	} else {
>> +	if (!ret) {
>>   		offset = PFN_DOWN(paddr - dma_addr);
>>
>>   		/*
>> @@ -128,6 +132,15 @@ void of_dma_configure(struct device *dev, struct device_node *np)
>>
>>   	dev->dma_pfn_offset = offset;
>>
>> +	/*
>> +	 * Limit coherent and dma mask based on size and default mask
>> +	 * set by the driver.
>> +	 */
>> +	dev->coherent_dma_mask = min(dev->coherent_dma_mask,
>> +				     DMA_BIT_MASK(ilog2(dma_addr + size)));
>
> Do we need to cover the case where size is incorrectly set to 0 in the
> DT? At least some warning and leaving the mask unchanged.

The previous series already warn and return if the size is incorrect 
(Patch v6 3/7) and leave the dma mask unchanged. So we don't have to do 
anything in this patch. I will fix the above and re-send.
>
>> +	*dev->dma_mask = min((*dev->dma_mask),
>> +			     DMA_BIT_MASK(ilog2(dma_addr + size)));
>> +
>>   	coherent = of_dma_is_coherent(np);
>>   	dev_dbg(dev, "device is%sdma coherent\n",
>>   		coherent ? " " : " not ");
>


-- 
Murali Karicheri
Linux Kernel, Texas Instruments