[Intel-gfx] [PATCH v4 1/2] drm/i915/mtl: limit second scaler vertical scaling in ver >= 14

[Luca Coelho]

In newer hardware versions (i.e. display version >= 14), the second
scaler doesn't support vertical scaling.

The current implementation of the scaling limits is simplified and
only occurs when the planes are created, so we don't know which scaler
is being used.

In order to handle separate scaling limits for horizontal and vertical
scaling, and different limits per scaler, split the checks in two
phases.  We first do a simple check during plane creation and use the
best-case scenario (because we don't know the scaler that may be used
at a later point) and then do a more specific check when the scalers
are actually being set up.

Signed-off-by: Luca Coelho <luciano.coelho at intel.com>
---
 drivers/gpu/drm/i915/display/intel_atomic.c | 83 ++++++++++++++++++---
 1 file changed, 73 insertions(+), 10 deletions(-)

In v2:
   * fix DRM_PLANE_NO_SCALING renamed macros;

In v3:
   * No changes.

In v4:
   * Got rid of the changes in the general planes max scale code;
   * Added a couple of FIXMEs;
   * Made intel_atomic_setup_scaler() return an int with errors;
   

diff --git a/drivers/gpu/drm/i915/display/intel_atomic.c b/drivers/gpu/drm/i915/display/intel_atomic.c
index 6621aa245caf..8373be283d8b 100644
--- a/drivers/gpu/drm/i915/display/intel_atomic.c
+++ b/drivers/gpu/drm/i915/display/intel_atomic.c
@@ -41,6 +41,7 @@
 #include "intel_global_state.h"
 #include "intel_hdcp.h"
 #include "intel_psr.h"
+#include "intel_fb.h"
 #include "skl_universal_plane.h"
 
 /**
@@ -310,11 +311,11 @@ intel_crtc_destroy_state(struct drm_crtc *crtc,
 	kfree(crtc_state);
 }
 
-static void intel_atomic_setup_scaler(struct intel_crtc_scaler_state *scaler_state,
-				      int num_scalers_need, struct intel_crtc *intel_crtc,
-				      const char *name, int idx,
-				      struct intel_plane_state *plane_state,
-				      int *scaler_id)
+static int intel_atomic_setup_scaler(struct intel_crtc_scaler_state *scaler_state,
+				     int num_scalers_need, struct intel_crtc *intel_crtc,
+				     const char *name, int idx,
+				     struct intel_plane_state *plane_state,
+				     int *scaler_id)
 {
 	struct drm_i915_private *dev_priv = to_i915(intel_crtc->base.dev);
 	int j;
@@ -334,7 +335,7 @@ static void intel_atomic_setup_scaler(struct intel_crtc_scaler_state *scaler_sta
 
 	if (drm_WARN(&dev_priv->drm, *scaler_id < 0,
 		     "Cannot find scaler for %s:%d\n", name, idx))
-		return;
+		return -EBUSY;
 
 	/* set scaler mode */
 	if (plane_state && plane_state->hw.fb &&
@@ -375,9 +376,69 @@ static void intel_atomic_setup_scaler(struct intel_crtc_scaler_state *scaler_sta
 		mode = SKL_PS_SCALER_MODE_DYN;
 	}
 
+	/*
+	 * FIXME: we should also check the scaler factors for pfit, so
+	 * this shouldn't be tied directly to planes.
+	 */
+	if (plane_state && plane_state->hw.fb) {
+		const struct drm_framebuffer *fb = plane_state->hw.fb;
+		struct drm_rect *src = &plane_state->uapi.src;
+		struct drm_rect *dst = &plane_state->uapi.dst;
+		int hscale, vscale, max_vscale, max_hscale;
+
+		/*
+		 * FIXME: When two scalers are needed, but only one of
+		 * them needs to downscale, we should make sure that
+		 * the one that needs downscaling support is assigned
+		 * as the first scaler, so we don't reject downscaling
+		 * unnecessarily.
+		 */
+
+		if (DISPLAY_VER(dev_priv) >= 14) {
+			/*
+			 * On versions 14 and up, only the first
+			 * scaler supports a vertical scaling factor
+			 * of more than 1.0, while a horizontal
+			 * scaling factor of 3.0 is supported.
+			 */
+			max_hscale = 0x30000 - 1;
+			if (*scaler_id == 0)
+				max_vscale = 0x30000 - 1;
+			else
+				max_vscale = 0x10000;
+
+		} else if (DISPLAY_VER(dev_priv) >= 10 ||
+			   !intel_format_info_is_yuv_semiplanar(fb->format, fb->modifier)) {
+			max_hscale = 0x30000 - 1;
+			max_vscale = 0x30000 - 1;
+		} else {
+			max_hscale = 0x20000 - 1;
+			max_vscale = 0x20000 - 1;
+		}
+
+		/* Check if required scaling is within limits */
+		hscale = drm_rect_calc_hscale(src, dst, 1, max_hscale);
+		vscale = drm_rect_calc_vscale(src, dst, 1, max_vscale);
+
+		if (hscale < 0 || vscale < 0) {
+			drm_dbg_kms(&dev_priv->drm,
+				    "Scaler %d doesn't support required plane scaling\n",
+				    *scaler_id);
+			drm_rect_debug_print("src: ", src, true);
+			drm_rect_debug_print("dst: ", dst, false);
+
+			scaler_state->scalers[*scaler_id].in_use = 0;
+			*scaler_id = -1;
+
+			return -EOPNOTSUPP;
+		}
+	}
+
 	drm_dbg_kms(&dev_priv->drm, "Attached scaler id %u.%u to %s:%d\n",
 		    intel_crtc->pipe, *scaler_id, name, idx);
 	scaler_state->scalers[*scaler_id].mode = mode;
+
+	return 0;
 }
 
 /**
@@ -437,7 +498,7 @@ int intel_atomic_setup_scalers(struct drm_i915_private *dev_priv,
 	for (i = 0; i < sizeof(scaler_state->scaler_users) * 8; i++) {
 		int *scaler_id;
 		const char *name;
-		int idx;
+		int idx, ret;
 
 		/* skip if scaler not required */
 		if (!(scaler_state->scaler_users & (1 << i)))
@@ -494,9 +555,11 @@ int intel_atomic_setup_scalers(struct drm_i915_private *dev_priv,
 			scaler_id = &plane_state->scaler_id;
 		}
 
-		intel_atomic_setup_scaler(scaler_state, num_scalers_need,
-					  intel_crtc, name, idx,
-					  plane_state, scaler_id);
+		ret = intel_atomic_setup_scaler(scaler_state, num_scalers_need,
+						intel_crtc, name, idx,
+						plane_state, scaler_id);
+		if (ret < 0)
+			return ret;
 	}
 
 	return 0;
-- 
2.38.1