> On 6/29/2013 11:10 AM, Akinobu Mita wrote:
>> 2013/6/29 James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>:
>>> On Wed, 2013-06-26 at 22:39 +0530, Santosh Y wrote:
>>>> index 19618c6..431ddb2 100644
>>>> --- a/drivers/scsi/ufs/ufshcd.c
>>>> +++ b/drivers/scsi/ufs/ufshcd.c
>>>> @@ -1711,6 +1711,25 @@ void ufshcd_remove(struct ufs_hba *hba)
>>>> EXPORT_SYMBOL_GPL(ufshcd_remove);
>>>>
>>>> /**
>>>> + * ufshcd_set_dma_mask - Set dma mask based on the controller
>>>> + * addressing capability
>>>> + * @hba: per adapter instance
>>>> + *
>>>> + * Returns 0 for success, non-zero for failure
>>>> + */
>>>> +static int ufshcd_set_dma_mask(struct ufs_hba *hba)
>>>> +{
>>>> + if (hba->capabilities & MASK_64_ADDRESSING_SUPPORT) {
>>>> + if (!dma_set_mask(hba->dev, DMA_BIT_MASK(64)) &&
>>>> + !dma_set_coherent_mask(hba->dev, DMA_BIT_MASK(64)))
>>>> + return 0;
>>>> + }
>>>> + dma_set_mask(hba->dev, DMA_BIT_MASK(32));
>>>> +
>>>> + return dma_set_coherent_mask(hba->dev, DMA_BIT_MASK(32));
>>>> +}
>>>
>>> This isn't right per the API spec. The guarantee is that if
>>> dma_set_mask() succeeds then dma_set_coherent_mask of the same mask
>>> will
>>> succeed, so this should read
>>>
>>> int err;
>>>
>>> if (hba->capabilities & MASK_64_ADDRESSING_SUPPORT) {
>>> if (!dma_set_mask(hba->dev, DMA_BIT_MASK(64))) {
>>> dma_set_coherent_mask(hba->dev,
>>> DMA_BIT_MASK(64)))
>>> return 0;
>>> }
>>> }
>>> err = dma_set_mask(hba->dev, DMA_BIT_MASK(32));
>>> if (!err)
>>> dma_set_coherent_mask(hba->dev, DMA_BIT_MASK(32));
>>> return err;
>>
>> Thanks for the explanation. I agree that this is the correct definision
>> of ufshcd_set_dma_mask().
>>
>> The reason that I omitted the error check on
>> dma_set_mask(DMA_BIT_MASK(32))
>> in the patch was that I was seeing that error due to the luck of
>> valid dev->dma_mask pointer on OF platform devices although
>> dma_supported(DMA_BIT_MASK(32)) returns true.
>
> The popular trick implemented for device-tree probed devices is -
> dev->dma_mask = &dev->coherent_dma_mask;
This looks the right solution for now. I'll send revised patches that
include this trick in ufshcd-pltfrm and fixed ufshcd_set_dma_mask() as
James suggested above.
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