[Intel-gfx] [PATCH 4/4] drm/i915: Do some basic sanity adjustments on the user provided mode

[ville.syrjala at linux.intel.com]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

Make sure the active, blanking and sync portions of the timings are in
the proper order. The contract with userspace basically is that we must
not increase the active portion. For the rest we're more or less free to
do as we please. A good rul IMO is that we only increase the non-active
portions of the timings.

We could do a lot more adjustment to make sure the timings meet all
the minimum requirements of the hardware. But as the mimimums may depend
on the output type and other details, we should perhaps do the adjustments
at some later point.

Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 60 ++++++++++++++++++++++++++++++++++--
 1 file changed, 58 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 7f61cfb..48cad99 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -8458,6 +8458,55 @@ static bool check_encoder_cloning(struct drm_crtc *crtc)
 	return !(num_encoders > 1 && uncloneable_encoders);
 }
 
+static void adjust_timings(struct drm_display_mode *mode,
+			   int *val, int min, int clocks_per_unit)
+{
+	if (*val >= min)
+		return;
+
+	/* maintain the same refresh rate */
+	mode->clock += (min - *val) * clocks_per_unit;
+
+	*val = min;
+}
+
+static int intel_adjust_mode(struct drm_display_mode *mode)
+{
+	if (mode->clock == 0) {
+		DRM_DEBUG_KMS("bad pixel clock\n");
+		drm_mode_debug_printmodeline(mode);
+		return -EINVAL;
+	}
+
+	if (mode->hdisplay == 0 || mode->vdisplay == 0) {
+		DRM_DEBUG_KMS("bad hdisplay or vdisplay\n");
+		drm_mode_debug_printmodeline(mode);
+		return -EINVAL;
+	}
+
+	adjust_timings(mode, &mode->hsync_start, mode->hdisplay, 0);
+	adjust_timings(mode, &mode->hsync_end, mode->hsync_start, 0);
+	adjust_timings(mode, &mode->htotal, mode->hsync_end, mode->vtotal);
+
+	adjust_timings(mode, &mode->vsync_start, mode->vdisplay, 0);
+	adjust_timings(mode, &mode->vsync_end, mode->vsync_start, 0);
+
+	/*
+	 * We must not increase the size of the active
+	 * space area for frame packing modes.
+	 */
+	if ((mode->flags & DRM_MODE_FLAG_3D_MASK) == DRM_MODE_FLAG_3D_FRAME_PACKING) {
+		if (mode->vtotal <  mode->vsync_end) {
+			DRM_DEBUG_KMS("refusing to adjust vtotal for frame packing mode\n");
+			drm_mode_debug_printmodeline(mode);
+			return -EINVAL;
+		}
+	} else
+		adjust_timings(mode, &mode->vtotal, mode->vsync_end, mode->htotal);
+
+	return 0;
+}
+
 static struct intel_crtc_config *
 intel_modeset_pipe_config(struct drm_crtc *crtc,
 			  struct drm_framebuffer *fb,
@@ -8466,7 +8515,7 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
 	struct drm_device *dev = crtc->dev;
 	struct intel_encoder *encoder;
 	struct intel_crtc_config *pipe_config;
-	int plane_bpp, ret = -EINVAL;
+	int plane_bpp, ret;
 	bool retry = true;
 
 	if (!check_encoder_cloning(crtc)) {
@@ -8498,14 +8547,20 @@ intel_modeset_pipe_config(struct drm_crtc *crtc,
 	      (DRM_MODE_FLAG_PVSYNC | DRM_MODE_FLAG_NVSYNC)))
 		pipe_config->adjusted_mode.flags |= DRM_MODE_FLAG_NVSYNC;
 
+	ret = intel_adjust_mode(&pipe_config->adjusted_mode);
+	if (ret)
+		goto fail;
+
 	/* Compute a starting value for pipe_config->pipe_bpp taking the source
 	 * plane pixel format and any sink constraints into account. Returns the
 	 * source plane bpp so that dithering can be selected on mismatches
 	 * after encoders and crtc also have had their say. */
 	plane_bpp = compute_baseline_pipe_bpp(to_intel_crtc(crtc),
 					      fb, pipe_config);
-	if (plane_bpp < 0)
+	if (plane_bpp < 0) {
+		ret = -EINVAL;
 		goto fail;
+	}
 
 	/* Determine the real pipe dimensions */
 	drm_mode_set_crtcinfo(&pipe_config->adjusted_mode, CRTC_STEREO_DOUBLE);
@@ -8532,6 +8587,7 @@ encoder_retry:
 
 		if (!(encoder->compute_config(encoder, pipe_config))) {
 			DRM_DEBUG_KMS("Encoder config failure\n");
+			ret = -EINVAL;
 			goto fail;
 		}
 	}
-- 
1.8.1.5