Rob, Grant, Re: http://www.spinics.net/lists/arm-kernel/msg148899.html Background: Tegra's DMA controller needs to be told which DMA "request select" to use for each transfer. The identifies which peripheral to transfer to/from. The Tegra I2S driver needs to know its own "request select" value to pass to the audio driver DMA path. The board files typically provide this to the driver as an IORESOURCE_DMA. I don't think there's any standard binding that creates such a resource when instantiating a platform device from device tree, and the discussions I found when looking for one didn't seem to reach conclusion that there should be one. So, I proposed the following property in the I2S driver's DT binding for this: Doc: - dma-channel : The Tegra DMA controller's channel ID for this I2S controller Example: i2s@70002800 { compatible = "nvidia,tegra20-i2s"; reg = <0x70002800 0x200>; interrupts = < 45 >; dma-channel = < 2 >; }; Does that look reasonable? Or, should I pursue some more standardized solution? (although perhaps dma-request-select would be a better name, since each of the DMA controller's 16 channels can be used for any of the DMA selects) For reference, the code turns out as below; it might be nicer if the DT parsing code could create this resource for us, although there was some previous discussion about IORESOURCE_DMA not being the correct representation for this anyway. dmareq = platform_get_resource(pdev, IORESOURCE_DMA, 0); if (!dmareq) { if (of_property_read_u32(pdev->dev.of_node, "nvidia,dma-channel", &dma_ch) < 0) { ... Thanks. -- nvpublic -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
