drm/i915/ltphy: Provide protection against unsupported modes

We need to make sure we return some port clock in case we have
unsupported LT PHY modes or if we were not able to read the LT PHY state
for whatever reason and the mode ends up being 0.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20260105055937.136522-3-suraj.kandpal@intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_lt_phy.c b/drivers/gpu/drm/i915/display/intel_lt_phy.c
index 9addb7661b6b629cf4d8a2523921763973df99ef..6cdae03ee172c0516e690d49e98bd4ca3d937621 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_lt_phy.c
+++ b/drivers/gpu/drm/i915/display/intel_lt_phy.c
@@ -31,6 +31,7 @@
 #define INTEL_LT_PHY_BOTH_LANES                (INTEL_LT_PHY_LANE1 |\
                                         INTEL_LT_PHY_LANE0)
 #define MODE_DP                                3
+#define MODE_HDMI_20                   4
 #define Q32_TO_INT(x)  ((x) >> 32)
 #define Q32_TO_FRAC(x) ((x) & 0xFFFFFFFF)
 #define DCO_MIN_FREQ_MHZ       11850
@@ -1751,6 +1752,7 @@ int
 intel_lt_phy_calc_port_clock(struct intel_encoder *encoder,
                             const struct intel_crtc_state *crtc_state)
 {
+       struct intel_display *display = to_intel_display(encoder);
        int clk;
        const struct intel_lt_phy_pll_state *lt_state =
                &crtc_state->dpll_hw_state.ltpll;
@@ -1768,8 +1770,11 @@ intel_lt_phy_calc_port_clock(struct intel_encoder *encoder,
                rate = REG_FIELD_GET8(LT_PHY_VDR_RATE_ENCODING_MASK,
                                      lt_state->config[0]);
                clk = intel_lt_phy_get_dp_clock(rate);
-       } else {
+       } else if (mode == MODE_HDMI_20) {
                clk = intel_lt_phy_calc_hdmi_port_clock(crtc_state);
+       } else {
+               drm_WARN_ON(display->drm, "Unsupported LT PHY Mode!\n");
+               clk = xe3plpd_lt_hdmi_252.clock;
        }
 
        return clk;