[PATCH] drm/i915/display: Add upper limit check for pixel clock

[Chaitanya Kumar Borah]

Add upper limit check for pixel clock by platform. Limits don't apply
when DSC is enabled.

For the currently supported versions of HDMI, pixel clock is already
limited to 600Mhz so nothing needs to be done there as of now.

BSpec: 49199, 68912

Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 12 ++++++++++++
 drivers/gpu/drm/i915/display/intel_display.h |  1 +
 drivers/gpu/drm/i915/display/intel_dp.c      |  3 +++
 3 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 456fc4b04cda..bf0faff50c2e 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -7902,6 +7902,18 @@ void intel_setup_outputs(struct intel_display *display)
 	drm_helper_move_panel_connectors_to_head(display->drm);
 }
 
+int intel_dotclock_limit(struct intel_display *display)
+{
+	if (DISPLAY_VERx100(display) == 3002)
+		return 937500;
+	else if (DISPLAY_VER(display) >= 30)
+		return 1350000;
+	else if (DISPLAY_VER(display) >= 13)
+		return 1200000;
+	else
+		return 1100000;
+}
+
 static int max_dotclock(struct intel_display *display)
 {
 	int max_dotclock = display->cdclk.max_dotclk_freq;
diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
index 37e2ab301a80..9ad896a15ba7 100644
--- a/drivers/gpu/drm/i915/display/intel_display.h
+++ b/drivers/gpu/drm/i915/display/intel_display.h
@@ -486,6 +486,7 @@ void intel_cpu_transcoder_get_m2_n2(struct intel_crtc *crtc,
 				    struct intel_link_m_n *m_n);
 int intel_dotclock_calculate(int link_freq, const struct intel_link_m_n *m_n);
 int intel_crtc_dotclock(const struct intel_crtc_state *pipe_config);
+int intel_dotclock_limit(struct intel_display *display);
 enum intel_display_power_domain intel_port_to_power_domain(struct intel_digital_port *dig_port);
 enum intel_display_power_domain
 intel_aux_power_domain(struct intel_digital_port *dig_port);
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index f48912f308df..3ff2beeed801 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1507,6 +1507,9 @@ intel_dp_mode_valid(struct drm_connector *_connector,
 		dsc = dsc_max_compressed_bpp && dsc_slice_count;
 	}
 
+	if (target_clock > (intel_dotclock_limit(display) * num_joined_pipes) && !dsc)
+		return MODE_CLOCK_HIGH;
+
 	if (intel_dp_joiner_needs_dsc(display, num_joined_pipes) && !dsc)
 		return MODE_CLOCK_HIGH;
 
-- 
2.25.1