Re: [PATCH v2 0/6] v4l2-subdev: Introduce get_mbus_format pad op

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Hi Jacopo,

Thank you for the patches.

On Wed, Apr 15, 2020 at 12:49:57PM +0200, Jacopo Mondi wrote:
> v2 introduces two new patches that could be likely squashed in later to
> deprecate the g_mbus_config() operation in documentation and expand the newly
> introduced function documentation by popular demand.
> 
> Will report again the use cases I'm trying to address here:
> ------------------------------------------------------------------------------
> Quoting:
> https://patchwork.kernel.org/cover/10855919/
> "The use case this series cover is the following one:
> the Gen-3 R-Car boards include an ADV748x HDMI/CVBS to CSI-2 converter
> connected to its CSI-2 receivers. The ADV748x chip has recently gained support
> for routing both HDMI and analogue video streams through its 4 lanes TXA
> transmitter, specifically to support the Ebisu board that has a single CSI-2
> receiver, compared to all other Gen-3 board where the ADV748x TXes are connected
> to different CSI-2 receivers, and where analogue video is streamed out from the
> ADV748x single lane TXB transmitter.
> To properly support transmission of analogue video through TXA, the number of
> data lanes shall be dynamically reduced to 1, in order to comply with the MIPI
> CSI-2 minimum clock frequency requirements"
> 
> During the discussion of the RFC, Dave reported another use case for media
> bus parameter negotiation on his platform:
> https://patchwork.kernel.org/patch/10855923/#22569149
> 
> Another possible use case is for parallel bus multiplexing, where multiple image
> sensor share the parallel bus lines and they get activated alternatively through
> an enable signal. While this might not be most clever design, it's often seen
> in the wild, and this operation allow receivers to re-configure their bus
> parameter in between streaming session.

Isn't this already supported today, with the bus configuration for each
source specified in the corresponding endpoint (on the receiver side) in
DT ?

> Hyun is now using this series to configure GMSL devices.
> ------------------------------------------------------------------------------
> 
> v1->v2:
> - Address Sakari's comment to use unsigned int in place of bools
> - Add two new patches to address documentation
> - Adjust rcar-csi2 patch as much as possible according to Niklas comments
> - Add Niklas's tags
> 
> Jacopo Mondi (6):
>   media: v4l2-subdv: Introduce get_mbus_config pad op
>   media: v4l2-subdev: Deprecate g_mbus_config video op
>   media: v4l2-subdev: Expand get_mbus_config doc
>   media: i2c: adv748x: Adjust TXA data lanes number
>   media: i2c: adv748x: Implement get_mbus_config
>   media: rcar-csi2: Negotiate data lanes number
> 
>  drivers/media/i2c/adv748x/adv748x-core.c    | 31 ++++++--
>  drivers/media/i2c/adv748x/adv748x-csi2.c    | 15 ++++
>  drivers/media/i2c/adv748x/adv748x.h         |  1 +
>  drivers/media/platform/rcar-vin/rcar-csi2.c | 53 ++++++++++++-
>  include/media/v4l2-subdev.h                 | 82 ++++++++++++++++++++-
>  5 files changed, 171 insertions(+), 11 deletions(-)
> 

-- 
Regards,

Laurent Pinchart



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