On Thursday, March 06, 2014 at 05:36:14 AM, Yao Yuan wrote: > On Thu, March 06, 2014 at 11:23:50 AM, Marek Vasut wrote: > > On Wednesday, March 05, 2014 at 07:52:31 AM, Yuan Yao wrote: > > > Add dma support for i2c. This function depend on DMA driver. > > > You can turn on it by write both the dmas and dma-name properties in > > > dts node. > > > > > > Signed-off-by: Yuan Yao <yao.y...@freescale.com> > > > --- > > > > [...] > > > > > @@ -601,6 +826,7 @@ static int i2c_imx_probe(struct platform_device > > > > *pdev) > > > > > void __iomem *base; > > > int irq, ret; > > > u32 bitrate; > > > > > > + u32 phy_addr; > > > > > > dev_dbg(&pdev->dev, "<%s>\n", __func__); > > > > > > @@ -611,6 +837,7 @@ static int i2c_imx_probe(struct platform_device > > > > *pdev) > > > > > } > > > > > > res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > > > > > + phy_addr = res->start; > > > > Uh ... Shawn, I really think I am lost here. Don't you need to map this > > memory before you can use it for DMA ? The DMA mapping function should > > give you the physical address and is the right way to go about this > > instead of pulling the address from here, no ? > > > > I might be wrong here, I am rather uncertain, so please help me out. > > Thanks! > > Hi, Marek, Thanks for your suggestion. > Here you can review the code in include/linux/ioport.h > The resource->start describes the entity on the CPU bus as a starting > physical address. So I thinks it can used for dma directly.
This doesn't feel right for some reason. If this is a register area, you should ioremap() it. If it's a memory area you do DMA to/from, you need to make sure you correctly flush/invalidate caches and properly handle the effects the write buffer might have. But I have a feeling you actually do DMA to/from register space here ? Best regards, Marek Vasut -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
