Introduce intel_dp_check_m_n_ratio() to validate the computed link
M/N ratio against the maximum allowed value. If the ratio exceeds the
limit, a warning is issued via drm_WARN().
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
drivers/gpu/drm/i915/display/intel_dp.c | 21 +++++++++++++++++++++
drivers/gpu/drm/i915/display/intel_dp.h | 3 +++
drivers/gpu/drm/i915/display/intel_dp_mst.c | 2 ++
drivers/gpu/drm/i915/display/intel_fdi.c | 2 ++
4 files changed, 28 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 39226c420917..83163b2913e2 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2995,6 +2995,23 @@ static bool can_enable_drrs(struct intel_connector *connector,
intel_panel_drrs_type(connector) == DRRS_TYPE_SEAMLESS;
}
+void intel_dp_check_m_n_ratio(struct intel_crtc_state *crtc_state,
+ struct intel_link_m_n *m_n)
+{
+ struct intel_display *display = to_intel_display(crtc_state);
+ int m_n_ratio;
+
+ if (!m_n || !m_n->link_n)
+ return;
+
+ m_n_ratio = DIV_ROUND_UP(m_n->link_m, m_n->link_n);
+
+ if (m_n_ratio > intel_dp_get_max_m_n_ratio())
+ drm_WARN(display->drm, 1,
+ "Link M/N ratio (%d) exceeds max allowed (%d)\n",
+ m_n_ratio, intel_dp_get_max_m_n_ratio());
+}
+
static void
intel_dp_drrs_compute_config(struct intel_connector *connector,
struct intel_crtc_state *pipe_config,
@@ -3033,6 +3050,8 @@ intel_dp_drrs_compute_config(struct intel_connector *connector,
intel_dp_bw_fec_overhead(pipe_config->fec_enable),
&pipe_config->dp_m2_n2);
+ intel_dp_check_m_n_ratio(pipe_config, &pipe_config->dp_m2_n2);
+
/* FIXME: abstract this better */
if (pipe_config->splitter.enable)
pipe_config->dp_m2_n2.data_m *= pipe_config->splitter.link_count;
@@ -3310,6 +3329,8 @@ intel_dp_compute_config(struct intel_encoder *encoder,
pipe_config->port_clock,
intel_dp_bw_fec_overhead(pipe_config->fec_enable),
&pipe_config->dp_m_n);
+
+ intel_dp_check_m_n_ratio(pipe_config, &pipe_config->dp_m_n);
}
ret = intel_dp_compute_min_hblank(pipe_config, conn_state);
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 16555a9c53c4..a197eb0a7fc6 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -22,6 +22,7 @@ struct intel_digital_port;
struct intel_display;
struct intel_dp;
struct intel_encoder;
+struct intel_link_m_n;
struct link_config_limits {
int min_rate, max_rate;
@@ -215,5 +216,7 @@ int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
int intel_dp_dsc_bpp_step_x16(const struct intel_connector *connector);
void intel_dp_dpcd_set_probe(struct intel_dp *intel_dp, bool force_on_external);
bool intel_dp_can_support_m_n(int pixel_clock, int link_rate);
+void intel_dp_check_m_n_ratio(struct intel_crtc_state *crtc_state,
+ struct intel_link_m_n *m_n);
#endif /* __INTEL_DP_H__ */
diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 62da0cb70607..45b72a2c8588 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -347,6 +347,8 @@ int intel_dp_mtp_tu_compute_config(struct intel_dp *intel_dp,
link_bpp_x16,
&crtc_state->dp_m_n);
+ intel_dp_check_m_n_ratio(crtc_state, &crtc_state->dp_m_n);
+
if (is_mst) {
int remote_bw_overhead;
int remote_tu;
diff --git a/drivers/gpu/drm/i915/display/intel_fdi.c b/drivers/gpu/drm/i915/display/intel_fdi.c
index 8039a84671cc..d8e9d6e108e8 100644
--- a/drivers/gpu/drm/i915/display/intel_fdi.c
+++ b/drivers/gpu/drm/i915/display/intel_fdi.c
@@ -349,6 +349,8 @@ int ilk_fdi_compute_config(struct intel_crtc *crtc,
intel_dp_bw_fec_overhead(false),
&pipe_config->fdi_m_n);
+ intel_dp_check_m_n_ratio(pipe_config, &pipe_config->dp_m_n);
+
return 0;
}
--
2.45.2