drm: atmel-hlcdc: fix atmel_xlcdc_plane_setup_scaler()

drm: atmel-hlcdc: fix atmel_xlcdc_plane_setup_scaler()

[ Upstream commit a312acdcec57b3955fbf1f3057c13a6d38e4aa2a ]

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@microchip.com>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Link: https://lore.kernel.org/r/20241014094942.325211-1-manikandan.m@microchip.com
Signed-off-by: Manikandan Muralidharan <manikandan.m@microchip.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>