[alsa-devel] [PATCH 0/2] ASoC: davinci: ping-pong buffers for mcasp on da850evm

Liam Girdwood lrg at ti.com
Thu May 19 13:08:09 CEST 2011

On 18/05/11 14:27, Ben Gardiner wrote:
> davinci-i2s enables the use of ping-pong buffers by copying the sram sizes
> specified by platform data into the dma params used by davinci-pcm.
> This patch series first implements that same behaviour in davinic-mcasp
> and then specified sram sizes and eventq's for da850evm.
> To achieve the use of ping-pong buffers at runtime this patch depends also
> on the conversion of da850's SRAM allocator to the "Share RAM" region from 
> the "ARM Local RAM" region -- originally proposed by Subhasish Ghosh[1] and
> recently reposted by myself [2].
> This is because the "ARM Local RAM" region currently used by the da850 SRAM
> allocator is not addressable by the EDMA. The resulting behaviour, when
> ping-pong buffers are used by davinci-pcm, is that playback produces silence
> and capture acquires silence.
> However, there is no change in behaviour for da850evm build with the in-tree
> defconfig since suspend allocates SRAM which prevents a successful allocation
> of 8K by davinci-pcm and thus the behaviour falls back to the usual scheme.
> In the case of da850evm builds where CONFIG_SUSPEND is not set, playback 
> will produce silence and capture will acquire silence until such time as the
> patches to change the da850 SRAM allocator to the "Shared RAM" region are 
> merged.
> [1] http://article.gmane.org/gmane.linux.kernel/1098928
> [2] http://article.gmane.org/gmane.linux.ports.arm.kernel/117261
> Ben Gardiner (2):
>   ASoC: davinci-mcasp: enable ping-pong SRAM buffers
>   davinci: da850evm: enable mcasp ping-pong buffers and eventq's
>  arch/arm/mach-davinci/board-da850-evm.c |    5 ++++-
>  sound/soc/davinci/davinci-mcasp.c       |    2 ++
>  2 files changed, 6 insertions(+), 1 deletions(-)


Acked-by: Liam Girdwood <lrg at ti.com>

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