[Intel-gfx] [PATCH 2/4] drm/i915/dsi: Enable dithering for 6 bpc panels
Ville Syrjälä
ville.syrjala at linux.intel.com
Tue Jan 15 14:55:10 UTC 2019
On Sat, Dec 01, 2018 at 12:31:46PM +0100, Hans de Goede wrote:
> The display engine has 2 dithering enable bits which both need to be set
> for dithering to happen, 1 in the PIPECONF register which is taken care of
> by i9xx_set_pipeconf() and a second bit at the encoder level.
>
> The dsi code was not setting the encoder level dithering enable bit causing
> dithering to be disabled, this commit fixes this.
>
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> ---
> drivers/gpu/drm/i915/vlv_dsi.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/vlv_dsi.c b/drivers/gpu/drm/i915/vlv_dsi.c
> index c10def5efa22..c21cbfa9653c 100644
> --- a/drivers/gpu/drm/i915/vlv_dsi.c
> +++ b/drivers/gpu/drm/i915/vlv_dsi.c
> @@ -711,6 +711,10 @@ static void intel_dsi_port_enable(struct intel_encoder *encoder,
> LANE_CONFIGURATION_DUAL_LINK_B :
> LANE_CONFIGURATION_DUAL_LINK_A;
> }
> +
> + if (intel_dsi->pixel_format != MIPI_DSI_FMT_RGB888)
> + temp |= DITHERING_ENABLE;
The docs say this was only made to work in C0 stepping. Not sure any
BYT-Ts were ever shipped with B2/3, nor am I sure if setting the bit
would have any effect there. IMO let's just set the bit and hope for
the best.
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> +
> /* assert ip_tg_enable signal */
> I915_WRITE(port_ctrl, temp | DPI_ENABLE);
> POSTING_READ(port_ctrl);
> --
> 2.19.1
--
Ville Syrjälä
Intel
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