[PATCH v7 19/36] drm/connector: hdmi: Compute bpc and format automatically

Maxime Ripard
2024-02-22T18:24:41Z

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.

Signed-off-by: Maxime Ripard <mripard@kernel.org>
---
drivers/gpu/drm/drm_atomic_state_helper.c | 184 ++++++++++++++++++++-
.../gpu/drm/tests/drm_atomic_state_helper_test.c | 25 ++-
2 files changed, 197 insertions(+), 12 deletions(-)

diff --git a/drivers/gpu/drm/drm_atomic_state_helper.c b/drivers/gpu/drm/drm_atomic_state_helper.c
index 448b4a73d1c8..9f517599f117 100644
--- a/drivers/gpu/drm/drm_atomic_state_helper.c
+++ b/drivers/gpu/drm/drm_atomic_state_helper.c
@@ -31,6 +31,7 @@
#include <drm/drm_connector.h>
#include <drm/drm_crtc.h>
#include <drm/drm_device.h>
+#include <drm/drm_edid.h>
#include <drm/drm_framebuffer.h>
#include <drm/drm_plane.h>
#include <drm/drm_print.h>
@@ -662,6 +663,96 @@ connector_state_get_mode(const struct drm_connector_state *conn_state)
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);
+
+ if (vic == 1 && bpc != 8) {
+ drm_dbg(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(dev, "DVI Monitors require an RGB output at 8 bpc\n");
+ return false;
+ }
+
+ if (!(connector->hdmi.supported_formats & BIT(format))) {
+ drm_dbg(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(dev, "RGB Format, checking the constraints.\n");
+
+ if (!(info->color_formats & DRM_COLOR_FORMAT_RGB444))
+ return false;
+
+ if (bpc == 10 && !(info->edid_hdmi_rgb444_dc_modes & DRM_EDID_HDMI_DC_30)) {
+ drm_dbg(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(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
+ return false;
+ }
+
+ drm_dbg(dev, "RGB format supported in that configuration.\n");
+
+ return true;
+
+ case HDMI_COLORSPACE_YUV422:
+ drm_dbg(dev, "YUV422 format, checking the constraints.\n");
+
+ if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR422)) {
+ drm_dbg(dev, "Sink doesn't support YUV422.\n");
+ return false;
+ }
+
+ if (bpc != 12) {
+ drm_dbg(dev, "YUV422 only supports 12 bpc.\n");
+ return false;
+ }
+
+ drm_dbg(dev, "YUV422 format supported in that configuration.\n");
+
+ return true;
+
+ case HDMI_COLORSPACE_YUV444:
+ drm_dbg(dev, "YUV444 format, checking the constraints.\n");
+
+ if (!(info->color_formats & DRM_COLOR_FORMAT_YCBCR444)) {
+ drm_dbg(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(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(dev, "12 BPC but sink doesn't support Deep Color 36.\n");
+ return false;
+ }
+
+ drm_dbg(dev, "YUV444 format supported in that configuration.\n");
+
+ return true;
+ }
+
+ return false;
+}
+
static enum drm_mode_status
hdmi_clock_valid(const struct drm_connector *connector,
const struct drm_display_mode *mode,
@@ -706,6 +797,95 @@ hdmi_compute_clock(const struct drm_connector *connector,
return 0;
}

+static bool
+hdmi_try_format_bpc(const struct drm_connector *connector,
+ struct drm_connector_state *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(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(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, state, mode, bpc, fmt);
+ if (ret) {
+ drm_dbg(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(dev, "%s output format supported with %u (TMDS char rate: %llu Hz)\n",
+ drm_hdmi_connector_get_output_format_name(fmt), bpc, state->hdmi.tmds_char_rate);
+
+ return true;
+}
+
+static int
+hdmi_compute_format(const struct drm_connector *connector,
+ struct drm_connector_state *state,
+ const struct drm_display_mode *mode,
+ unsigned int bpc)
+{
+ struct drm_device *dev = connector->dev;
+
+ if (hdmi_try_format_bpc(connector, state, mode, bpc, HDMI_COLORSPACE_RGB)) {
+ state->hdmi.output_format = HDMI_COLORSPACE_RGB;
+ return 0;
+ }
+
+ if (hdmi_try_format_bpc(connector, state, mode, bpc, HDMI_COLORSPACE_YUV422)) {
+ state->hdmi.output_format = HDMI_COLORSPACE_YUV422;
+ return 0;
+ }
+
+ drm_dbg(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 *state,
+ const struct drm_display_mode *mode)
+{
+ struct drm_device *dev = connector->dev;
+ unsigned int max_bpc = clamp_t(unsigned int,
+ state->max_bpc,
+ 8, connector->max_bpc);
+ unsigned int bpc;
+ int ret;
+
+ for (bpc = max_bpc; bpc >= 8; bpc -= 2) {
+ drm_dbg(dev, "Trying with a %d bpc output\n", bpc);
+
+ ret = hdmi_compute_format(connector, state, mode, bpc);
+ if (ret)
+ continue;
+
+ state->hdmi.output_bpc = bpc;
+
+ drm_dbg(dev,
+ "Mode %ux%u @ %uHz: Found configuration: bpc: %u, fmt: %s, clock: %llu\n",
+ mode->hdisplay, mode->vdisplay, drm_mode_vrefresh(mode),
+ state->hdmi.output_bpc,
+ drm_hdmi_connector_get_output_format_name(state->hdmi.output_format),
+ 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
@@ -729,9 +909,7 @@ int drm_atomic_helper_connector_hdmi_check(struct drm_connector *connector,
connector_state_get_mode(new_state);
int ret;

- ret = hdmi_compute_clock(connector, new_state, mode,
- new_state->hdmi.output_bpc,
- new_state->hdmi.output_format);
+ ret = hdmi_compute_config(connector, new_state, mode);
if (ret)
return ret;

diff --git a/drivers/gpu/drm/tests/drm_atomic_state_helper_test.c b/drivers/gpu/drm/tests/drm_atomic_state_helper_test.c
index 5a8750153510..f010fde0eb69 100644
--- a/drivers/gpu/drm/tests/drm_atomic_state_helper_test.c
+++ b/drivers/gpu/drm/tests/drm_atomic_state_helper_test.c
@@ -70,9 +70,6 @@ static int light_up_connector(struct kunit *test,
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);

@@ -251,10 +248,15 @@ static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
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);

@@ -272,11 +274,11 @@ static void drm_test_check_output_bpc_crtc_mode_changed(struct kunit *test)
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);
@@ -320,10 +322,15 @@ static void drm_test_check_output_bpc_crtc_mode_not_changed(struct kunit *test)
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);

@@ -670,7 +677,7 @@ static void drm_test_check_format_value(struct kunit *test)

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);
}

/*

--
2.43.2