Re: [PATCH v6 11/14] media: uapi: Add a control for DW100 driver

From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: Xavier Roumegue <xavier.roumegue@oss.nxp.com>
Cc: mchehab@kernel.org, hverkuil-cisco@xs4all.nl,
	stanimir.varbanov@linaro.org, tomi.valkeinen@ideasonboard.com,
	robh+dt@kernel.org, nicolas@ndufresne.ca,
	alexander.stein@ew.tq-group.com, linux-media@vger.kernel.org,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v6 11/14] media: uapi: Add a control for DW100 driver
Date: Fri, 8 Jul 2022 13:50:36 +0300	[thread overview]
Message-ID: <YsgL/E58FfgeKzmb@pendragon.ideasonboard.com> (raw)
In-Reply-To: <20220623143115.3185297-12-xavier.roumegue@oss.nxp.com>

Hi Xavier,

Thank you for the patch.

On Thu, Jun 23, 2022 at 04:31:12PM +0200, Xavier Roumegue wrote:
> The DW100 driver gets the dewarping mapping as a binary blob from the
> userspace application through a custom control.
> The blob format is hardware specific so create a dedicated control for
> this purpose.
> 
> Signed-off-by: Xavier Roumegue <xavier.roumegue@oss.nxp.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> ---
>  .../userspace-api/media/drivers/dw100.rst          | 13 +++++++++++++
>  include/uapi/linux/dw100.h                         | 14 ++++++++++++++
>  2 files changed, 27 insertions(+)
>  create mode 100644 include/uapi/linux/dw100.h
> 
> diff --git a/Documentation/userspace-api/media/drivers/dw100.rst b/Documentation/userspace-api/media/drivers/dw100.rst
> index 1ca6fa55f539..d8a6e10b4395 100644
> --- a/Documentation/userspace-api/media/drivers/dw100.rst
> +++ b/Documentation/userspace-api/media/drivers/dw100.rst
> @@ -66,4 +66,17 @@ map.
>  More details on the DW100 hardware operations can be found in
>  *chapter 13.15 DeWarp* of IMX8MP_ reference manual.
>  
> +The Vivante DW100 m2m driver implements the following driver-specific control:
> +
> +``V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP (__u32 array)``
> +    Specifies to DW100 driver its dewarping map (aka LUT) blob as described in
> +    *chapter 13.15.2.3 Dewarping Remap* of IMX8MP_ reference manual as an U32
> +    dynamic array. The image is divided into many small 16x16 blocks. If the
> +    width/height of the image is not divisible by 16, the size of the
> +    rightmost/bottommost block is the remainder. The dewarping map only saves
> +    the vertex coordinates of the block. The dewarping grid map is comprised of
> +    vertex coordinates for x and y. Each x, y coordinate register uses 16 bits
> +    (UQ12.4) to record the coordinate address, with the Y coordinate in the
> +    upper bits and X in the lower bits.

I would add "The driver modifies the dimensions of this control when the
sink format is changed, to reflect the new input resolution." or
something similar.

> +
>  .. _IMX8MP: https://www.nxp.com/webapp/Download?colCode=IMX8MPRM
> diff --git a/include/uapi/linux/dw100.h b/include/uapi/linux/dw100.h
> new file mode 100644
> index 000000000000..3356496edd6b
> --- /dev/null
> +++ b/include/uapi/linux/dw100.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
> +/* Copyright 2022 NXP */
> +
> +#ifndef __UAPI_DW100_H__
> +#define __UAPI_DW100_H__
> +
> +#include <linux/v4l2-controls.h>
> +
> +/*
> + * Check Documentation/userspace-api/media/drivers/dw100.rst for control details.
> + */
> +#define V4L2_CID_DW100_DEWARPING_16x16_VERTEX_MAP (V4L2_CID_USER_DW100_BASE + 1)
> +
> +#endif

-- 
Regards,

Laurent Pinchart