drm/i915/psr: fix pipe to vblank conversion

First, we can't assume pipe == crtc index. If a pipe is fused off in
between, it no longer holds. intel_crtc_for_pipe() is the only proper
way to get from a pipe to the corresponding crtc.

Second, drivers aren't supposed to access or index drm->vblank[]
directly. There's drm_crtc_vblank_crtc() for this.

Use both functions to fix the pipe to vblank conversion.

Fixes: f02658c ("drm/i915/psr: Add mechanism to notify PSR of pipe enable/disable")
Cc: Jouni Högander <jouni.hogander@intel.com>
Cc: stable@vger.kernel.org # v6.16+
Reviewed-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patch.msgid.link/20251106200000.1455164-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
(cherry picked from commit 2750f67)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Author: jnikula

drivers/gpu/drm/i915/display/intel_psr.c

@@ -888,7 +888,8 @@ static bool is_dc5_dc6_blocked(struct intel_dp *intel_dp)
 {
 	struct intel_display *display = to_intel_display(intel_dp);
 	u32 current_dc_state = intel_display_power_get_current_dc_state(display);
-	struct drm_vblank_crtc *vblank = &display->drm->vblank[intel_dp->psr.pipe];
+	struct intel_crtc *crtc = intel_crtc_for_pipe(display, intel_dp->psr.pipe);
+	struct drm_vblank_crtc *vblank = drm_crtc_vblank_crtc(&crtc->base);
 
 	return (current_dc_state != DC_STATE_EN_UPTO_DC5 &&
 		current_dc_state != DC_STATE_EN_UPTO_DC6) ||