On 11/15/2013 09:54 PM, Stephen Warren wrote:
From: Stephen Warren swarren@nvidia.com
Add fields to struct snd_dmaengine_pcm_config to allow custom:
DMA channel names.
This is useful when the default "tx" and "rx" channel names don't apply, for example if a HW module supports multiple channels, each having different DMA channel names. This is the case with the FIFOs in Tegra's AHUB. This new facility can replace SND_DMAENGINE_PCM_FLAG_CUSTOM_CHANNEL_NAME.
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 module contains its own FIFOs which DMA writes to. However, in Tegra30, the DMA FIFOs were split out AHUB HW module, which then routes the data through a cross-bar, and into the DAI HW modules. However, the current ASoC driver structure does not expose this detail, and acts as if the FIFOs are still part of the DAI HW modules. Consequently, the "PCM" driver is registered with the DAI HW module, yet the DMA channels must be looked up in the AHUB HW module's device tree node. This new config field allows that to happen. Eventually, the Tegra drivers will be reworked to fully expose the AHUB, and this config field can be removed.
Cc: treding@nvidia.com Cc: linux-tegra@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: Liam Girdwood lgirdwood@gmail.com Cc: Mark Brown broonie@kernel.org Cc: alsa-devel@alsa-project.org Signed-off-by: Stephen Warren swarren@nvidia.com
Acked-by: Lars-Peter Clausen lars@metafoo.de