drm/i915: reject modes the LPT FDI receiver can't handle
More specifically, the LPT FDI RX only supports 8bpc and a maximum of
2 lanes, so anything above that won't work and should be rejected.
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index 5c77743..3084d01 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -198,6 +198,11 @@
if (mode->clock > max_clock)
return MODE_CLOCK_HIGH;
+ /* The FDI receiver on LPT only supports 8bpc and only has 2 lanes. */
+ if (HAS_PCH_LPT(dev) &&
+ (ironlake_get_lanes_required(mode->clock, 270000, 24) > 2))
+ return MODE_CLOCK_HIGH;
+
return MODE_OK;
}
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f8ee3d1..41e2d95 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5228,6 +5228,17 @@
}
}
+int ironlake_get_lanes_required(int target_clock, int link_bw, int bpp)
+{
+ /*
+ * Account for spread spectrum to avoid
+ * oversubscribing the link. Max center spread
+ * is 2.5%; use 5% for safety's sake.
+ */
+ u32 bps = target_clock * bpp * 21 / 20;
+ return bps / (link_bw * 8) + 1;
+}
+
static void ironlake_set_m_n(struct drm_crtc *crtc,
struct drm_display_mode *mode,
struct drm_display_mode *adjusted_mode)
@@ -5281,15 +5292,9 @@
else
target_clock = adjusted_mode->clock;
- if (!lane) {
- /*
- * Account for spread spectrum to avoid
- * oversubscribing the link. Max center spread
- * is 2.5%; use 5% for safety's sake.
- */
- u32 bps = target_clock * intel_crtc->bpp * 21 / 20;
- lane = bps / (link_bw * 8) + 1;
- }
+ if (!lane)
+ lane = ironlake_get_lanes_required(target_clock, link_bw,
+ intel_crtc->bpp);
intel_crtc->fdi_lanes = lane;
diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 3915ca9..8a1bd4a 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -559,6 +559,7 @@
enum pipe pipe);
extern void intel_wait_for_vblank(struct drm_device *dev, int pipe);
extern void intel_wait_for_pipe_off(struct drm_device *dev, int pipe);
+extern int ironlake_get_lanes_required(int target_clock, int link_bw, int bpp);
struct intel_load_detect_pipe {
struct drm_framebuffer *release_fb;