Re: [PATCH] ASoC: omap-pcm: Lower the dma coherent mask to 32bits

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

One note for the patch:

On 12/10/2013 11:37 AM, Peter Ujfalusi wrote:
> Hi Russell,
> 
> On 12/09/2013 07:03 PM, Russell King - ARM Linux wrote:
>> Yes, that's a good idea.  Revised version of the patch.  Peter, can you
>> retest please, thanks.
> 
> With this patch PandaES and BeagleXM works fine on top of today's mainline.
> 
> Thank you Russell and Takashi!
> 
> Tested-by: Peter Ujfalusi <peter.ujfalusi@ti.com>


> 
>> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
>> index f6b6bfa88ecf..86c564e52ea7 100644
>> --- a/arch/arm/mm/dma-mapping.c
>> +++ b/arch/arm/mm/dma-mapping.c
>> @@ -158,6 +158,44 @@ struct dma_map_ops arm_coherent_dma_ops = {
>>  };
>>  EXPORT_SYMBOL(arm_coherent_dma_ops);
>>  
>> +static int __dma_supported(struct device *dev, u64 mask, bool warn)
>> +{
>> +	unsigned long max_dma_pfn;
>> +
>> +	/*
>> +	 * If the mask allows for more memory than we can address,
>> +	 * and we actually have that much memory, then we must
>> +	 * indicate that DMA to this device is not supported.
>> +	 */
>> +	if (sizeof(mask) != sizeof(dma_addr_t) &&
>> +	    mask > (dma_addr_t)~0 &&
>> +	    dma_to_pfn(dev, ~0) < max_pfn) {
>> +		if (warn) {
>> +			dev_warn(dev, "Coherent DMA mask %#llx is larger than dma_addr_t allows\n",
>> +				 mask);
>> +			dev_warn(dev, "Driver did not use or check the return value from dma_set_coherent_mask()?\n");
>> +		}
>> +		return 0;
>> +	}
>> +
>> +	max_dma_pfn = min(max_pfn, arm_dma_pfn_limit);
>> +
>> +	/*
>> +	 * Translate the device's DMA mask to a PFN limit.  This
>> +	 * PFN number includes the page which we can DMA to.
>> +	 */
>> +	if (dma_to_pfn(dev, mask) < max_dma_pfn) {
>> +		if (warn)
>> +			dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n",
>> +				 mask,
>> +				 dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1,
>> +				 max_dma_pfn + 1);
>> +		return 0;
>> +	}
>> +
>> +	return 1;
>> +}
>> +
>>  static u64 get_coherent_dma_mask(struct device *dev)
>>  {
>>  	u64 mask = (u64)DMA_BIT_MASK(32);

  CC      arch/arm/mach-omap2/control.o
arch/arm/mm/dma-mapping.c: In function ‘get_coherent_dma_mask’:
arch/arm/mm/dma-mapping.c:204:17: warning: unused variable ‘max_dma_pfn’ [-Wunused-variable]
   unsigned long max_dma_pfn;
                 ^


>> @@ -176,34 +214,8 @@ static u64 get_coherent_dma_mask(struct device *dev)
>>  			return 0;
>>  		}
>>  
>> -		max_dma_pfn = min(max_pfn, arm_dma_pfn_limit);
>> -
>> -		/*
>> -		 * If the mask allows for more memory than we can address,
>> -		 * and we actually have that much memory, then fail the
>> -		 * allocation.
>> -		 */
>> -		if (sizeof(mask) != sizeof(dma_addr_t) &&
>> -		    mask > (dma_addr_t)~0 &&
>> -		    dma_to_pfn(dev, ~0) > max_dma_pfn) {
>> -			dev_warn(dev, "Coherent DMA mask %#llx is larger than dma_addr_t allows\n",
>> -				 mask);
>> -			dev_warn(dev, "Driver did not use or check the return value from dma_set_coherent_mask()?\n");
>> -			return 0;
>> -		}
>> -
>> -		/*
>> -		 * Now check that the mask, when translated to a PFN,
>> -		 * fits within the allowable addresses which we can
>> -		 * allocate.
>> -		 */
>> -		if (dma_to_pfn(dev, mask) < max_dma_pfn) {
>> -			dev_warn(dev, "Coherent DMA mask %#llx (pfn %#lx-%#lx) covers a smaller range of system memory than the DMA zone pfn 0x0-%#lx\n",
>> -				 mask,
>> -				 dma_to_pfn(dev, 0), dma_to_pfn(dev, mask) + 1,
>> -				 arm_dma_pfn_limit + 1);
>> +		if (!__dma_supported(dev, mask, true))
>>  			return 0;
>> -		}
>>  	}
>>  
>>  	return mask;
>> @@ -1032,28 +1044,7 @@ void arm_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
>>   */
>>  int dma_supported(struct device *dev, u64 mask)
>>  {
>> -	unsigned long limit;
>> -
>> -	/*
>> -	 * If the mask allows for more memory than we can address,
>> -	 * and we actually have that much memory, then we must
>> -	 * indicate that DMA to this device is not supported.
>> -	 */
>> -	if (sizeof(mask) != sizeof(dma_addr_t) &&
>> -	    mask > (dma_addr_t)~0 &&
>> -	    dma_to_pfn(dev, ~0) > arm_dma_pfn_limit)
>> -		return 0;
>> -
>> -	/*
>> -	 * Translate the device's DMA mask to a PFN limit.  This
>> -	 * PFN number includes the page which we can DMA to.
>> -	 */
>> -	limit = dma_to_pfn(dev, mask);
>> -
>> -	if (limit < arm_dma_pfn_limit)
>> -		return 0;
>> -
>> -	return 1;
>> +	return __dma_supported(dev, mask, false);
>>  }
>>  EXPORT_SYMBOL(dma_supported);
>>  
>>
> 
> 


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