linux-kernel - Re: [PATCH] drm: atmel-hlcdc: fix atmel_xlcdc_plane_setup

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Message-ID: <7106870f-6452-47b1-9251-ce2a69366fe7@microchip.com>
Date: Mon, 21 Oct 2024 09:56:31 +0200
From: Nicolas Ferre <nicolas.ferre@...rochip.com>
To: Manikandan Muralidharan <manikandan.m@...rochip.com>, <sam@...nborg.org>,
	<bbrezillon@...nel.org>, <maarten.lankhorst@...ux.intel.com>,
	<mripard@...nel.org>, <tzimmermann@...e.de>, <airlied@...il.com>,
	<simona@...ll.ch>, <alexandre.belloni@...tlin.com>,
	<claudiu.beznea@...on.dev>, <Hari.PrasathGE@...rochip.com>,
	<durai.manickamkr@...rochip.com>, <dri-devel@...ts.freedesktop.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC: Cyrille Pitchen <cyrille.pitchen@...rochip.com>
Subject: Re: [PATCH] drm: atmel-hlcdc: fix atmel_xlcdc_plane_setup_scaler()

On 14/10/2024 at 11:49, Manikandan Muralidharan wrote:
> From: Cyrille Pitchen <cyrille.pitchen@...rochip.com>
> 
> On SoCs, like the SAM9X75, which embed the XLCDC ip, the registers that
> configure the unified scaling engine were not filled with proper values.
> 
> Indeed, for YCbCr formats, the VXSCFACT bitfield of the HEOCFG25
> register and the HXSCFACT bitfield of the HEOCFG27 register were
> incorrect.
> 
> For 4:2:0 formats, both vertical and horizontal factors for
> chroma chanels should be divided by 2 from the factors for the luma
> channel. Hence:
> 
> HEOCFG24.VXSYFACT = VFACTOR
> HEOCFG25.VSXCFACT = VFACTOR / 2
> HEOCFG26.HXSYFACT = HFACTOR
> HEOCFG27.HXSCFACT = HFACTOR / 2
> 
> However, for 4:2:2 formats, only the horizontal factor for chroma
> chanels should be divided by 2 from the factor for the luma channel;
> the vertical factor is the same for all the luma and chroma channels.
> Hence:
> 
> HEOCFG24.VXSYFACT = VFACTOR
> HEOCFG25.VXSCFACT = VFACTOR
> HEOCFG26.HXSYFACT = HFACTOR
> HEOCFG27.HXSCFACT = HFACTOR / 2
> 
> Fixes: d498771b0b83 ("drm: atmel_hlcdc: Add support for XLCDC using IP specific driver ops")
> Signed-off-by: Cyrille Pitchen <cyrille.pitchen@...rochip.com>

Thanks Mani and Cyrille:
Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>

Best regards,
  Nicolas

> ---
>   .../gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c   | 27 ++++++++++++++++---
>   1 file changed, 24 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
> index 4bcaf2cd7672..41c7351ae811 100644
> --- a/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
> +++ b/drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_plane.c
> @@ -365,13 +365,34 @@ void atmel_xlcdc_plane_setup_scaler(struct atmel_hlcdc_plane *plane,
>   				    xfactor);
>   
>   	/*
> -	 * With YCbCr 4:2:2 and YCbYcr 4:2:0 window resampling, configuration
> -	 * register LCDC_HEOCFG25.VXSCFACT and LCDC_HEOCFG27.HXSCFACT is half
> +	 * With YCbCr 4:2:0 window resampling, configuration register
> +	 * LCDC_HEOCFG25.VXSCFACT and LCDC_HEOCFG27.HXSCFACT values are half
>   	 * the value of yfactor and xfactor.
> +	 *
> +	 * On the other hand, with YCbCr 4:2:2 window resampling, only the
> +	 * configuration register LCDC_HEOCFG27.HXSCFACT value is half the value
> +	 * of the xfactor; the value of LCDC_HEOCFG25.VXSCFACT is yfactor (no
> +	 * division by 2).
>   	 */
> -	if (state->base.fb->format->format == DRM_FORMAT_YUV420) {
> +	switch (state->base.fb->format->format) {
> +	/* YCbCr 4:2:2 */
> +	case DRM_FORMAT_YUYV:
> +	case DRM_FORMAT_UYVY:
> +	case DRM_FORMAT_YVYU:
> +	case DRM_FORMAT_VYUY:
> +	case DRM_FORMAT_YUV422:
> +	case DRM_FORMAT_NV61:
> +		xfactor /= 2;
> +		break;
> +
> +	/* YCbCr 4:2:0 */
> +	case DRM_FORMAT_YUV420:
> +	case DRM_FORMAT_NV21:
>   		yfactor /= 2;
>   		xfactor /= 2;
> +		break;
> +	default:
> +		break;
>   	}
>   
>   	atmel_hlcdc_layer_write_cfg(&plane->layer, desc->layout.scaler_config + 2,