On 11/16/2013 02:44 AM, Mark Brown wrote:
On Fri, Nov 15, 2013 at 01:54:10PM -0700, Stephen Warren wrote:
- DMA device
This allows requesting DMA channels for a device other than the device which is registering the "PCM" driver. This is quite unusual, but is currently useful on Tegra. In much HW, and in Tegra20, each DAI HW
...
I'm a bit concerned about anything actually using dma_dev since it indicates that something is being worked around, it'd be a bit nicer to print a warning when doing this to give people a hint that they might not be doing the right thing if they use it (unless someone comes up with a system that has a clear use case for it).
What if I squash the following into that patch:
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index 1160d1cba133..0e2645dee96a 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -296,8 +296,17 @@ static int dmaengine_pcm_request_chan_of(struct dmaengine_pcm *pcm, !dev->of_node) return 0;
- if (config->dma_dev)
if (config->dma_dev) {
/** If this warning is seen, it probably means that your Linux* device structure does not match your HW device structure.* It would be best to refactor the Linux device structure to* correctly match the HW structure.*/dev_warn(dev, "DMA channels sourced from device %s",dev_name(config->dma_dev));dev = config->dma_dev;
}
for (i = SNDRV_PCM_STREAM_PLAYBACK; i <= SNDRV_PCM_STREAM_CAPTURE; i++) {
(a few patches later) That yields the following warning on Tegra, for example:
[ 2.629623] tegra30-i2s 70080400.i2s: DMA channels sourced from device 70080000.ahub