On 6/29/2013 11:10 AM, Akinobu Mita wrote:
2013/6/29 James Bottomley <james.bottom...@hansenpartnership.com>:
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;
If you don't agree with this you can have something like -
dev->dma_mask = devm_kzalloc(dev, sizeof(*dev->dma_mask), GFP_KERNEL);
See platform_device_register_full();
However, now I think that I should investigate more about dev->dma_mask
issue rather than jumping into short-circuit fixing in the driver. And
then I will revisit this.
--
Regards,
Sujit
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