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
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