linux-kernel - Re: [PATCH] staging: bcm2835-camera: Add TODO for removing overlay support

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Date:   Fri, 11 May 2018 10:21:18 +0100
From:   Dave Stevenson <dave.stevenson@...pberrypi.org>
To:     Stefan Schake <stschake@...il.com>
Cc:     Eric Anholt <eric@...olt.net>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Greg KH <gregkh@...uxfoundation.org>,
        "moderated list:BROADCOM BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@...ts.infradead.org>, devel@...verdev.osuosl.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] staging: bcm2835-camera: Add TODO for removing overlay support

On 11 May 2018 at 00:12, Stefan Schake <stschake@...il.com> wrote:
> The overlay code is non-functional since it relies on firmware control
> of the HVS.
>
> Signed-off-by: Stefan Schake <stschake@...il.com>
> ---
> Dave, does this match your understanding?

Yes, the overlay only works if you are not running the vc4 driver,
therefore dropping it is sensible for the mainline kernel.

>  drivers/staging/vc04_services/bcm2835-camera/TODO | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/staging/vc04_services/bcm2835-camera/TODO b/drivers/staging/vc04_services/bcm2835-camera/TODO
> index 0ab9e88..770fea6 100644
> --- a/drivers/staging/vc04_services/bcm2835-camera/TODO
> +++ b/drivers/staging/vc04_services/bcm2835-camera/TODO
> @@ -32,3 +32,11 @@ We should have VCHI create a platform device once it's initialized,
>  and have this driver bind to it, so that we automatically load the
>  v4l2 module after VCHI loads.
>
> +5) Remove overlay support.
> +
> +We advertise support for a V4L2 overlay implemented through the
> +ril.video_render component. This component is non-functional with an
> +upstream kernel since the VC4 DRM driver controls the HVS, not the
> +firmware. Once we have dma-buf support, the same functionality with
> +improved control can be achieved through the DRM interface. We should
> +therefore remove all V4L2 overlay functionality from the driver.
> --
> 2.7.4
>