[Intel-gfx] [PATCH] drm/i915/ehl: Check VBT before updating the transcoder for pipe

[Vivek Kasireddy]

Since the pipe->transcoder mapping is not expected to change unless
there is either eDP or DSI connectors present, check the VBT to confirm
their presence in addition to checking TRANS_DDI_FUNC_CTL(transcoder).
This additional check is needed on platforms like Elkhart Lake because
we cannot just rely on GOP/Firmware programmed values in
TRANS_DDI_FUNC_CTL(transcoder) before updating the transcoder mapping.

This patch is only relevant to EHL -- and a no-op on others --
because some of the PHYs are shared between the different DDIs and
we rely on the VBT to present the most accurate information to the
driver.

Cc: Matt Roper <matthew.d.roper at intel.com>
Cc: José Roberto de Souza <jose.souza at intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index c0e5002ce64c..4b38f293bd88 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -10805,6 +10805,18 @@ static void hsw_get_ddi_pll(struct drm_i915_private *dev_priv, enum port port,
 	pipe_config->shared_dpll = intel_get_shared_dpll_by_id(dev_priv, id);
 }
 
+static bool ehl_vbt_edp_dsi_present(struct drm_i915_private *dev_priv,
+				    enum transcoder transcoder)
+{
+	bool edp_present = intel_bios_is_port_present(dev_priv, PORT_A);
+	bool dsi_present = intel_bios_is_dsi_present(dev_priv, NULL);
+
+	if (IS_ELKHARTLAKE(dev_priv))
+		return transcoder == TRANSCODER_EDP ? edp_present : dsi_present;
+
+	return true;
+}
+
 static bool hsw_get_transcoder_state(struct intel_crtc *crtc,
 				     struct intel_crtc_state *pipe_config,
 				     u64 *power_domain_mask,
@@ -10844,7 +10856,8 @@ static bool hsw_get_transcoder_state(struct intel_crtc *crtc,
 
 		tmp = intel_de_read(dev_priv,
 				    TRANS_DDI_FUNC_CTL(panel_transcoder));
-		if (!(tmp & TRANS_DDI_FUNC_ENABLE))
+		if (!(tmp & TRANS_DDI_FUNC_ENABLE) ||
+		    !ehl_vbt_edp_dsi_present(dev_priv, panel_transcoder))
 			continue;
 
 		/*
-- 
2.21.1