On Tue, May 21, 2024 at 12:13:48PM +0200, Maxime Ripard wrote:
> Now that we have all the infrastructure needed, we can add some code
> that will, for a given connector state and mode, compute the best output
> format and bpc.
>
> The algorithm is equivalent to the one already found in i915 and vc4.
>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
> ---
> drivers/gpu/drm/display/drm_hdmi_state_helper.c | 205 ++++++++++++++++++++-
> drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c | 25 ++-
> 2 files changed, 218 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> index 063421835dba..93cb30dba86e 100644
> --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c
> @@ -1,9 +1,11 @@
> // SPDX-License-Identifier: MIT
>
> #include <drm/drm_atomic.h>
> #include <drm/drm_connector.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_print.h>
>
> #include <drm/display/drm_hdmi_helper.h>
> #include <drm/display/drm_hdmi_state_helper.h>
>
> /**
> @@ -46,10 +48,118 @@ connector_state_get_mode(const struct drm_connector_state *conn_state)
> return NULL;
>
> return &crtc_state->mode;
> }
>
> +static bool
> +sink_supports_format_bpc(const struct drm_connector *connector,
> + const struct drm_display_info *info,
> + const struct drm_display_mode *mode,
> + unsigned int format, unsigned int bpc)
> +{
> + struct drm_device *dev = connector->dev;
> + u8 vic = drm_match_cea_mode(mode);
> +
> + /*
> + * CTA-861-F, section 5.4 - Color Coding & Quantization states
> + * that the bpc must be 8, 10, 12 or 16 except for the default
> + * 640x480 VIC1 where the value must be 8.
> + *
> + * The definition of default here is ambiguous but the spec
> + * refers to VIC1 being the default timing in several occasions
> + * so our understanding is that for the default timing (ie,
> + * VIC1), the bpc must be 8.
> + */
> + if (vic == 1 && bpc != 8) {
> + drm_dbg_kms(dev, "VIC1 requires a bpc of 8, got %u\n", bpc);
> + return false;
> + }
> +
> + if (!info->is_hdmi &&
> + (format != HDMI_COLORSPACE_RGB || bpc != 8)) {
> + drm_dbg_kms(dev, "DVI Monitors require an RGB output at 8 bpc\n");
> + return false;
> + }
> +
> + if (!(connector->hdmi.supported_formats & BIT(format))) {
> + drm_dbg_kms(dev, "%s format unsupported by the connector.\n",
> + drm_hdmi_connector_get_output_format_name(format));
> + return false;
> + }
> +
> + switch (format) {
> + case HDMI_COLORSPACE_RGB:
> + drm_dbg_kms(dev, "RGB Format, checking the constraints.\n");
> +
> + /*
> + * In some cases, like when the EDID readout fails, or
> + * is not an HDMI compliant EDID for some reason, the
> + * color_formats field will be blank and not report any
> + * format supported. In such a case, assume that RGB is
> + * supported so we can keep things going and light up
> + * the display.
> + */
> + if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
> + drm_warn(dev, "HDMI Sink doesn't support RGB, something's wrong.\n");
> +
> + if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
> + drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
> + return false;
> + }
> +
> + if (bpc == 12 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_36)) {
> + drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
> + return false;
> + }
> +
> + drm_dbg_kms(dev, "RGB format supported in that configuration.\n");
> +
> + return true;
> +
> + case HDMI_COLORSPACE_YUV422:
> + drm_dbg_kms(dev, "YUV422 format, checking the constraints.\n");
> +
> + if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR422)) {
> + drm_dbg_kms(dev, "Sink doesn't support YUV422.\n");
> + return false;
> + }
> +
> + if (bpc != 12) {
> + drm_dbg_kms(dev, "YUV422 only supports 12 bpc.\n");
> + return false;
> + }
Maybe I'm misunderstanding the spec for YUV 4:2:2
> +
> + drm_dbg_kms(dev, "YUV422 format supported in that configuration.\n");
> +
> + return true;
> +
> + case HDMI_COLORSPACE_YUV444:
> + drm_dbg_kms(dev, "YUV444 format, checking the constraints.\n");
> +
> + if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR444)) {
> + drm_dbg_kms(dev, "Sink doesn't support YUV444.\n");
> + return false;
> + }
> +
> + if (bpc == 10 && !(info->edid_hdmi_ycbcr444_dc_modes & DRM_EDID_HDMI_DC_30)) {
> + drm_dbg_kms(dev, "10 BPC but sink doesn't support Deep Color 30.\n");
> + return false;
> + }
> +
> + if (bpc == 12 && !(info->edid_hdmi_ycbcr444_dc_modes & DRM_EDID_HDMI_DC_36)) {
> + drm_dbg_kms(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
> + return false;
> + }
> +
> + drm_dbg_kms(dev, "YUV444 format supported in that configuration.\n");
> +
> + return true;
So for 4:2:0 this code will always return false? I think a dev_dbg /
todo / comment would be nice. There is a todo later on, but it is in a
different code block.
> + }
> +
> + return false;
> +}
> +
> static enum drm_mode_status
> hdmi_clock_valid(const struct drm_connector *connector,
> const struct drm_display_mode *mode,
> unsigned long long clock)
> {
> @@ -90,10 +200,101 @@ hdmi_compute_clock(const struct drm_connector *connector,
> conn_state->hdmi.tmds_char_rate = clock;
>
> return 0;
> }
>
> +static bool
> +hdmi_try_format_bpc(const struct drm_connector *connector,
> + struct drm_connector_state *conn_state,
> + const struct drm_display_mode *mode,
> + unsigned int bpc, enum hdmi_colorspace fmt)
> +{
> + const struct drm_display_info *info = &connector->display_info;
> + struct drm_device *dev = connector->dev;
> + int ret;
> +
> + drm_dbg_kms(dev, "Trying %s output format\n",
> + drm_hdmi_connector_get_output_format_name(fmt));
> +
> + if (!sink_supports_format_bpc(connector, info, mode, fmt, bpc)) {
> + drm_dbg_kms(dev, "%s output format not supported with %u bpc\n",
> + drm_hdmi_connector_get_output_format_name(fmt),
> + bpc);
> + return false;
> + }
> +
> + ret = hdmi_compute_clock(connector, conn_state, mode, bpc, fmt);
> + if (ret) {
> + drm_dbg_kms(dev, "Couldn't compute clock for %s output format and %u bpc\n",
> + drm_hdmi_connector_get_output_format_name(fmt),
> + bpc);
> + return false;
> + }
> +
> + drm_dbg_kms(dev, "%s output format supported with %u (TMDS char rate: %llu Hz)\n",
> + drm_hdmi_connector_get_output_format_name(fmt),
> + bpc, conn_state->hdmi.tmds_char_rate);
> +
> + return true;
> +}
> +
> +static int
> +hdmi_compute_format(const struct drm_connector *connector,
> + struct drm_connector_state *conn_state,
> + const struct drm_display_mode *mode,
> + unsigned int bpc)
> +{
> + struct drm_device *dev = connector->dev;
> +
> + /*
> + * TODO: Add support for YCbCr420 output for HDMI 2.0 capable
> + * devices, for modes that only support YCbCr420.
> + */
> + if (hdmi_try_format_bpc(connector, conn_state, mode, bpc, HDMI_COLORSPACE_RGB)) {
> + conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
> + return 0;
> + }
> +
> + drm_dbg_kms(dev, "Failed. No Format Supported for that bpc count.\n");
> +
> + return -EINVAL;
> +}
> +
> +static int
> +hdmi_compute_config(const struct drm_connector *connector,
> + struct drm_connector_state *conn_state,
> + const struct drm_display_mode *mode)
> +{
> + struct drm_device *dev = connector->dev;
> + unsigned int max_bpc = clamp_t(unsigned int,
> + conn_state->max_bpc,
> + 8, connector->max_bpc);
> + unsigned int bpc;
> + int ret;
> +
> + for (bpc = max_bpc; bpc >= 8; bpc -= 2) {
> + drm_dbg_kms(dev, "Trying with a %d bpc output\n", bpc);
> +
> + ret = hdmi_compute_format(connector, conn_state, mode, bpc);
> + if (ret)
> + continue;
> +
> + conn_state->hdmi.output_bpc = bpc;
> +
> + drm_dbg_kms(dev,
> + "Mode %ux%u @ %uHz: Found configuration: bpc: %u, fmt: %s, clock: %llu\n",
> + mode->hdisplay, mode->vdisplay, drm_mode_vrefresh(mode),
> + conn_state->hdmi.output_bpc,
> + drm_hdmi_connector_get_output_format_name(conn_state->hdmi.output_format),
> + conn_state->hdmi.tmds_char_rate);
> +
> + return 0;
> + }
> +
> + return -EINVAL;
> +}
> +
> /**
> * drm_atomic_helper_connector_hdmi_check() - Helper to check HDMI connector atomic state
> * @connector: DRM Connector
> * @state: the DRM State object
> *
> @@ -113,13 +314,11 @@ int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
> drm_atomic_get_new_connector_state(state, connector);
> const struct drm_display_mode *mode =
> connector_state_get_mode(new_conn_state);
> int ret;
>
> - ret = hdmi_compute_clock(connector, new_conn_state, mode,
> - new_conn_state->hdmi.output_bpc,
> - new_conn_state->hdmi.output_format);
> + ret = hdmi_compute_config(connector, new_conn_state, mode);
> if (ret)
> return ret;
>
> if (old_conn_state->hdmi.output_bpc != new_conn_state->hdmi.output_bpc ||
> old_conn_state->hdmi.output_format != new_conn_state->hdmi.output_format) {
> diff --git a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
> index ead998a691e7..a49a544d7b49 100644
> --- a/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
> +++ b/drivers/gpu/drm/tests/drm_hdmi_state_helper_test.c
> @@ -70,13 +70,10 @@ static int light_up_connector(struct kunit *test,
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, state);
>
> conn_state = drm_atomic_get_connector_state(state, connector);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, conn_state);
>
> - conn_state->hdmi.output_bpc = connector->max_bpc;
> - conn_state->hdmi.output_format = HDMI_COLORSPACE_RGB;
> -
> ret = drm_atomic_set_crtc_for_connector(conn_state, crtc);
> KUNIT_EXPECT_EQ(test, ret, 0);
>
> crtc_state = drm_atomic_get_crtc_state(state, crtc);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, crtc_state);
> @@ -251,14 +248,19 @@ static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
> priv = drm_atomic_helper_connector_hdmi_init(test,
> BIT(HDMI_COLORSPACE_RGB),
> 10);
> KUNIT_ASSERT_NOT_NULL(test, priv);
>
> + conn = &priv->connector;
> + ret = set_connector_edid(test, conn,
> + test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz,
> + ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz));
> + KUNIT_ASSERT_EQ(test, ret, 0);
> +
> ctx = drm_kunit_helper_acquire_ctx_alloc(test);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
>
> - conn = &priv->connector;
> preferred = find_preferred_mode(conn);
> KUNIT_ASSERT_NOT_NULL(test, preferred);
>
> drm = &priv->drm;
> crtc = priv->crtc;
> @@ -272,15 +274,15 @@ static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, new_conn_state);
>
> old_conn_state = drm_atomic_get_old_connector_state(state, conn);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, old_conn_state);
>
> - new_conn_state->hdmi.output_bpc = 8;
> + new_conn_state->max_requested_bpc = 8;
>
> KUNIT_ASSERT_NE(test,
> - old_conn_state->hdmi.output_bpc,
> - new_conn_state->hdmi.output_bpc);
> + old_conn_state->max_requested_bpc,
> + new_conn_state->max_requested_bpc);
>
> ret = drm_atomic_check_only(state);
> KUNIT_ASSERT_EQ(test, ret, 0);
>
> old_conn_state = drm_atomic_get_old_connector_state(state, conn);
> @@ -320,14 +322,19 @@ static void drm_test_check_output_bpc_crtc_mode_not_changed(struct kunit *test)
> priv = drm_atomic_helper_connector_hdmi_init(test,
> BIT(HDMI_COLORSPACE_RGB),
> 10);
> KUNIT_ASSERT_NOT_NULL(test, priv);
>
> + conn = &priv->connector;
> + ret = set_connector_edid(test, conn,
> + test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz,
> + ARRAY_SIZE(test_edid_hdmi_1080p_rgb_yuv_dc_max_200mhz));
> + KUNIT_ASSERT_EQ(test, ret, 0);
> +
> ctx = drm_kunit_helper_acquire_ctx_alloc(test);
> KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ctx);
>
> - conn = &priv->connector;
> preferred = find_preferred_mode(conn);
> KUNIT_ASSERT_NOT_NULL(test, preferred);
>
> drm = &priv->drm;
> crtc = priv->crtc;
> @@ -670,11 +677,11 @@ static void drm_test_check_format_value(struct kunit *test)
> 8);
> KUNIT_ASSERT_NOT_NULL(test, priv);
>
> conn = &priv->connector;
> conn_state = conn->state;
> - KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, HDMI_COLORSPACE_RGB);
> + KUNIT_EXPECT_EQ(test, conn_state->hdmi.output_format, 0);
> }
>
> /*
> * Test that the value of the output format property out of reset is set
> * to 0, and will be computed at atomic_check time.
>
> --
> 2.45.0
>
--
With best wishes
Dmitry
