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Date: Mon, 8 Apr 2024 09:50:19 +0200
From: Louis Chauvet <louis.chauvet@bootlin.com>
To: Philipp Zabel <p.zabel@pengutronix.de>
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Subject: Re: [PATCH v5 11/16] drm/vkms: Add YUV support
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References: <20240313-yuv-v5-0-e610cbd03f52@bootlin.com>
 <20240313-yuv-v5-11-e610cbd03f52@bootlin.com>
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Le 27/03/24 - 13:11, Philipp Zabel a ?crit :
> Hi Louis,
> 
> On Mi, 2024-03-13 at 18:45 +0100, Louis Chauvet wrote:
> > From: Arthur Grillo <arthurgrillo@riseup.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