linux-kernel - Re: [PATCH v5 11/16] drm/vkms: Add YUV support

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Date: Mon, 8 Apr 2024 09:50:19 +0200
From: Louis Chauvet <louis.chauvet@...tlin.com>
To: Philipp Zabel <p.zabel@...gutronix.de>
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@...il.com>,
	Melissa Wen <melissa.srw@...il.com>,
	Maíra Canal <mairacanal@...eup.net>,
	Haneen Mohammed <hamohammed.sa@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, arthurgrillo@...eup.net,
	Jonathan Corbet <corbet@....net>, pekka.paalanen@...oniitty.fi,
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
	jeremie.dautheribes@...tlin.com, miquel.raynal@...tlin.com,
	thomas.petazzoni@...tlin.com, seanpaul@...gle.com,
	marcheu@...gle.com, nicolejadeyee@...gle.com
Subject: Re: [PATCH v5 11/16] drm/vkms: Add YUV support

Le 27/03/24 - 13:11, Philipp Zabel a écrit :
> Hi Louis,
> 
> On Mi, 2024-03-13 at 18:45 +0100, Louis Chauvet wrote:
> > From: Arthur Grillo <arthurgrillo@...eup.net>
> > 
> > Add support to the YUV formats bellow:
> > 
> > - NV12/NV16/NV24
> > - NV21/NV61/NV42
> > - YUV420/YUV422/YUV444
> > - YVU420/YVU422/YVU444
> > 
> > The conversion from yuv to rgb is done with fixed-point arithmetic, using
> > 32.32 floats and the drm_fixed helpers.
> 
> s/floats/fixed-point numbers/
> 
> Nothing floating here, the point is fixed.
> 
> [...]
> > diff --git a/drivers/gpu/drm/vkms/vkms_drv.h b/drivers/gpu/drm/vkms/vkms_drv.h
> > index 23e1d247468d..f3116084de5a 100644
> > --- a/drivers/gpu/drm/vkms/vkms_drv.h
> > +++ b/drivers/gpu/drm/vkms/vkms_drv.h
> > @@ -99,6 +99,27 @@ typedef void (*pixel_read_line_t)(const struct vkms_plane_state *plane, int x_st
> >  				  int y_start, enum pixel_read_direction direction, int count,
> >  				  struct pixel_argb_u16 out_pixel[]);
> >  
> > +/**
> > + * CONVERSION_MATRIX_FLOAT_DEPTH - Number of digits after the point for conversion matrix values
> 
> s/CONVERSION_MATRIX_FLOAT_DEPTH/CONVERSION_MATRIX_FRACTIONAL_BITS/
> 
> Just a suggestion, maybe there are better terms, but using "FLOAT" here
> is confusing.
> 
> > + */
> > +#define CONVERSION_MATRIX_FLOAT_DEPTH 32
> > +
> > +/**
> > + * struct conversion_matrix - Matrix to use for a specific encoding and range
> > + *
> > + * @matrix: Conversion matrix from yuv to rgb. The matrix is stored in a row-major manner and is
> > + * used to compute rgb values from yuv values:
> > + *     [[r],[g],[b]] = @matrix * [[y],[u],[v]]
> > + *   OR for yvu formats:
> > + *     [[r],[g],[b]] = @matrix * [[y],[v],[u]]
> > + *  The values of the matrix are fixed floats, 32.CONVERSION_MATRIX_FLOAT_DEPTH
> 
> s/fixed floats/fixed-point numbers/

Thanks for those precision, I will change the wording in v6.

Louis Chauvet
 
> regards
> Philipp

-- 
Louis Chauvet, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com