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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 




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
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]
  Powered by Linux