Hi all, I am writing a very simple KMS driver that uses Xilinx VDMA to transfer data between the host and a FPGA. To handle memory allocation for DMA I am using the CMA helpers available in the DRM subsystem. When setting for low video modes (small memory requirements) everything works fine, but if I try to set a large video mode (specifically a 4k HDMI mode) I get SWIOTLB errors saying the buffer is full. The distinction between CMA and SWIOTLB is not clear to me, but these are two different allocation engines, right? One important aspect in my configuration is that the Xilinx VDMA can only access up to 28 bits of the host memory so I set the DMA mask to 28 bits and force the CMA region to be allocated bellow these 28 bits. I also tried increasing the CMA size and the SWIOTLB size without success. Any comments on this? Thanks in advance for your help. Best regards, Jose Miguel Abreu -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
