LayerscapeのトピックLS1021A: DMA memory allocation for PCIe Device https://community.nxp.com/t5/Layerscape/LS1021A-DMA-memory-allocation-for-PCIe-Device/m-p/617083#M1825 <HTML><HEAD></HEAD><BODY><P>In a Linux kernel module I'm using dma_alloc_coherent() to allocate memory for a PCI device to DMA data into the ARM DDR.</P><P>I have noticed that the kernel virtual address and dma_handle returned by this function are always the same.</P><P></P><P>Does this mean SMMU2 and MMU are using the same table or SMMU2 is disabled in Linux?&nbsp;</P><P></P><P>Also do I need to set the DMA mask to 32 " DMA_BIT_MASK(32)" &nbsp;for PCIe device or something else?</P><P></P><P>Do I need to configure the iATU inbound for the DMA to work or just the outbound Linux default configuration is enough?</P><P></P><P>Thanks</P></BODY></HTML> Tue, 13 Sep 2016 15:35:36 GMT Tarek 2016-09-13T15:35:36Z LS1021A: DMA memory allocation for PCIe Device https://community.nxp.com/t5/Layerscape/LS1021A-DMA-memory-allocation-for-PCIe-Device/m-p/617083#M1825 <HTML><HEAD></HEAD><BODY><P>In a Linux kernel module I'm using dma_alloc_coherent() to allocate memory for a PCI device to DMA data into the ARM DDR.</P><P>I have noticed that the kernel virtual address and dma_handle returned by this function are always the same.</P><P></P><P>Does this mean SMMU2 and MMU are using the same table or SMMU2 is disabled in Linux?&nbsp;</P><P></P><P>Also do I need to set the DMA mask to 32 " DMA_BIT_MASK(32)" &nbsp;for PCIe device or something else?</P><P></P><P>Do I need to configure the iATU inbound for the DMA to work or just the outbound Linux default configuration is enough?</P><P></P><P>Thanks</P></BODY></HTML> Tue, 13 Sep 2016 15:35:36 GMT https://community.nxp.com/t5/Layerscape/LS1021A-DMA-memory-allocation-for-PCIe-Device/m-p/617083#M1825 Tarek 2016-09-13T15:35:36Z