Re: [PATCH 4/4] drm/bridge: dw-hdmi: Add support for RGB limited range
From: Jernej Åkrabec
Date: Mon Mar 02 2020 - 11:49:03 EST
Hi Laurent!
Dne ponedeljek, 02. marec 2020 ob 10:53:54 CET je Laurent Pinchart napisal(a):
> Hi Jernej,
>
> Thank you for the patch.
>
> On Sat, Feb 29, 2020 at 05:30:43PM +0100, Jernej Skrabec wrote:
> > CEA 861 standard request that RGB quantization range is "limited" for
>
> s/request/requests/
>
> > CEA modes. Support that by adding CSC matrix which downscales values.
>
> Interesting, that's related to what I asked in the review of 2/4 :-)
>
> > This allows to proper color reproduction on TV and PC monitor at the
> > same time. In future, override property can be added, like "Broadcast
> > RGB" in i915 driver.
> >
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@xxxxxxxx>
> > ---
> >
> > drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 36 +++++++++++++++++++++--
> > 1 file changed, 34 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index
> > 3d6021119942..101c90156fa0 100644
> > --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> > @@ -92,6 +92,12 @@ static const u16 csc_coeff_rgb_in_eitu709[3][4] = {
> >
> > { 0x6756, 0x78ab, 0x2000, 0x0200 }
> >
> > };
> >
> > +static const u16 csc_coeff_rgb_limited[3][4] = {
>
> Could you name this to make it explicit that we're converting from RGB
> to RGB ? Maybe csc_coeff_rgb_full_to_rgb_limited ?
Ok.
>
> > + { 0x1B7C, 0x0000, 0x0000, 0x0020 },
> > + { 0x0000, 0x1B7C, 0x0000, 0x0020 },
> > + { 0x0000, 0x0000, 0x1B7C, 0x0020 }
>
> Lowercase hex constants please.
Ok.
>
> > +};
> > +
> >
> > struct hdmi_vmode {
> >
> > bool mdataenablepolarity;
> >
> > @@ -109,6 +115,7 @@ struct hdmi_data_info {
> >
> > unsigned int pix_repet_factor;
> > unsigned int hdcp_enable;
> > struct hdmi_vmode video_mode;
> >
> > + bool rgb_limited_range;
> >
> > };
> >
> > struct dw_hdmi_i2c {
> >
> > @@ -960,6 +967,13 @@ static int is_color_space_conversion(struct dw_hdmi
> > *hdmi)>
> > hdmi_bus_fmt_is_rgb(hdmi-
>hdmi_data.enc_out_bus_format);
> >
> > }
> >
> > +static int is_rgb_downscale_needed(struct dw_hdmi *hdmi)
> > +{
> > + return hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_in_bus_format) &&
> > + hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_out_bus_format)
&&
> > + hdmi->hdmi_data.rgb_limited_range;
> > +}
> > +
> >
> > static int is_color_space_decimation(struct dw_hdmi *hdmi)
> > {
> >
> > if (!hdmi_bus_fmt_is_yuv422(hdmi->hdmi_data.enc_out_bus_format))
> >
> > @@ -1006,6 +1020,8 @@ static void dw_hdmi_update_csc_coeffs(struct dw_hdmi
> > *hdmi)>
> > csc_coeff =
&csc_coeff_rgb_in_eitu709;
> >
> > csc_scale = 0;
> >
> > }
> >
> > + } else if (is_rgb_downscale_needed(hdmi)) {
> > + csc_coeff = &csc_coeff_rgb_limited;
> >
> > }
> >
> > /* The CSC registers are sequential, alternating MSB then LSB */
> >
> > @@ -1615,6 +1631,18 @@ static void hdmi_config_AVI(struct dw_hdmi *hdmi,
> > struct drm_display_mode *mode)>
> > drm_hdmi_avi_infoframe_from_display_mode(&frame,
> >
> > &hdmi-
>connector, mode);
> >
> > + if (hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_out_bus_format)) {
> > + drm_hdmi_avi_infoframe_quant_range(&frame, &hdmi-
>connector,
> > + mode,
> > + hdmi-
>hdmi_data.rgb_limited_range ?
> > +
HDMI_QUANTIZATION_RANGE_LIMITED :
> > +
HDMI_QUANTIZATION_RANGE_FULL);
> > + } else {
> > + frame.quantization_range =
HDMI_QUANTIZATION_RANGE_DEFAULT;
> > + frame.ycc_quantization_range =
> > + HDMI_YCC_QUANTIZATION_RANGE_LIMITED;
> > + }
> > +
> >
> > if (hdmi_bus_fmt_is_yuv444(hdmi->hdmi_data.enc_out_bus_format))
> >
> > frame.colorspace = HDMI_COLORSPACE_YUV444;
> >
> > else if (hdmi_bus_fmt_is_yuv422(hdmi-
>hdmi_data.enc_out_bus_format))
> >
> > @@ -1990,13 +2018,13 @@ static void dw_hdmi_enable_video_path(struct
> > dw_hdmi *hdmi)>
> > hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
> >
> > /* Enable csc path */
> >
> > - if (is_color_space_conversion(hdmi)) {
> > + if (is_color_space_conversion(hdmi) ||
is_rgb_downscale_needed(hdmi)) {
>
> I would fold this change in is_color_space_conversion(), and modify
> dw_hdmi_update_csc_coeffs() accordingly with something like
>
> if (!hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_in_bus_format) &&
> hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_out_bus_format)) {
> if (hdmi->hdmi_data.enc_out_encoding ==
V4L2_YCBCR_ENC_601)
> csc_coeff = &csc_coeff_rgb_out_eitu601;
> else
> csc_coeff = &csc_coeff_rgb_out_eitu709;
> } else if (hdmi_bus_fmt_is_rgb(hdmi->hdmi_data.enc_in_bus_format)
&&
> !hdmi_bus_fmt_is_rgb(hdmi-
>hdmi_data.enc_out_bus_format)) {
> if (hdmi->hdmi_data.enc_out_encoding ==
V4L2_YCBCR_ENC_601)
> csc_coeff = &csc_coeff_rgb_in_eitu601;
> else
> csc_coeff = &csc_coeff_rgb_in_eitu709;
> csc_scale = 0;
> } else if (is_rgb_downscale_needed(hdmi)) {
> csc_coeff = &csc_coeff_rgb_limited;
> }
Right, but for clarity reasons I'll introduce is_input_rgb and is_output_rgb
variables.
Thanks for review.
Best regards,
Jernej
>
> > hdmi->mc_clkdis &= ~HDMI_MC_CLKDIS_CSCCLK_DISABLE;
> > hdmi_writeb(hdmi, hdmi->mc_clkdis, HDMI_MC_CLKDIS);
> >
> > }
> >
> > /* Enable color space conversion if needed */
> >
> > - if (is_color_space_conversion(hdmi))
> > + if (is_color_space_conversion(hdmi) ||
is_rgb_downscale_needed(hdmi))
> >
> > hdmi_writeb(hdmi,
HDMI_MC_FLOWCTRL_FEED_THROUGH_OFF_CSC_IN_PATH,
> >
> > HDMI_MC_FLOWCTRL);
> >
> > else
> >
> > @@ -2100,6 +2128,10 @@ static int dw_hdmi_setup(struct dw_hdmi *hdmi,
> > struct drm_display_mode *mode)>
> > /* TOFIX: Default to RGB888 output format */
> > hdmi->hdmi_data.enc_out_bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> >
> > + hdmi->hdmi_data.rgb_limited_range = hdmi->sink_is_hdmi &&
> > + drm_default_rgb_quant_range(mode) ==
> > + HDMI_QUANTIZATION_RANGE_LIMITED;
> > +
> >
> > hdmi->hdmi_data.pix_repet_factor = 0;
> > hdmi->hdmi_data.hdcp_enable = 0;
> > hdmi->hdmi_data.video_mode.mdataenablepolarity = true;