On 10/09/2013 04:29 PM, Archit Taneja wrote:
> VPE is a block which consists of a single memory to memory path which can
> perform chrominance up/down sampling, de-interlacing, scaling, and color space
> conversion of raster or tiled YUV420 coplanar, YUV422 coplanar or YUV422
> interleaved video formats.
>
> We create a mem2mem driver based primarily on the mem2mem-testdev example.
> The de-interlacer, scaler and color space converter are all bypassed for now
> to keep the driver simple. Chroma up/down sampler blocks are implemented, so
> conversion beteen different YUV formats is possible.
>
> Each mem2mem context allocates a buffer for VPE MMR values which it will use
> when it gets access to the VPE HW via the mem2mem queue, it also allocates
> a VPDMA descriptor list to which configuration and data descriptors are added.
>
> Based on the information received via v4l2 ioctls for the source and
> destination queues, the driver configures the values for the MMRs, and stores
> them in the buffer. There are also some VPDMA parameters like frame start and
> line mode which needs to be configured, these are configured by direct
> register
> writes via the VPDMA helper functions.
>
> The driver's device_run() mem2mem op will add each descriptor based on how the
> source and destination queues are set up for the given ctx, once the list is
> prepared, it's submitted to VPDMA, these descriptors when parsed by VPDMA will
> upload MMR registers, start DMA of video buffers on the various input and
> output
> clients/ports.
>
> When the list is parsed completely(and the DMAs on all the output ports done),
> an interrupt is generated which we use to notify that the source and
> destination
> buffers are done.
>
> The rest of the driver is quite similar to other mem2mem drivers, we use the
> multiplane v4l2 ioctls as the HW support coplanar formats.
>
> Signed-off-by: Archit Taneja <arc...@ti.com>
Acked-by: Hans Verkuil <hans.verk...@cisco.com>
Regards,
Hans
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