3 files changed, 45 insertions, 0 deletions

diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index cc85c16cbc2a..ae2e16ed3874 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -23,6 +23,7 @@
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_mode.h>
 #include <drm/drm_plane_helper.h>
+#include <linux/math64.h>
 
 #include "omap_drv.h"
 
@@ -400,6 +401,41 @@ static void omap_crtc_atomic_disable(struct drm_crtc *crtc,
         drm_crtc_vblank_off(crtc);
 }
 
+static enum drm_mode_status omap_crtc_mode_valid(struct drm_crtc *crtc,
+                                        const struct drm_display_mode *mode)
+{
+        struct omap_drm_private *priv = crtc->dev->dev_private;
+
+        /* Check for bandwidth limit */
+        if (priv->max_bandwidth) {
+                /*
+                 * Estimation for the bandwidth need of a given mode with one
+                 * full screen plane:
+                 * bandwidth = resolution * 32bpp * (pclk / (vtotal * htotal))
+                 *                                      ^^ Refresh rate ^^
+                 *
+                 * The interlaced mode is taken into account by using the
+                 * pixelclock in the calculation.
+                 *
+                 * The equation is rearranged for 64bit arithmetic.
+                 */
+                uint64_t bandwidth = mode->clock * 1000;
+                unsigned int bpp = 4;
+
+                bandwidth = bandwidth * mode->hdisplay * mode->vdisplay * bpp;
+                bandwidth = div_u64(bandwidth, mode->htotal * mode->vtotal);
+
+                /*
+                 * Reject modes which would need more bandwidth if used with one
+                 * full resolution plane (most common use case).
+                 */
+                if (priv->max_bandwidth < bandwidth)
+                        return MODE_BAD;
+        }
+
+        return MODE_OK;
+}
+
 static void omap_crtc_mode_set_nofb(struct drm_crtc *crtc)
 {
         struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
@@ -621,6 +657,7 @@ static const struct drm_crtc_helper_funcs omap_crtc_helper_funcs = {
         .atomic_flush = omap_crtc_atomic_flush,
         .atomic_enable = omap_crtc_atomic_enable,
         .atomic_disable = omap_crtc_atomic_disable,
+        .mode_valid = omap_crtc_mode_valid,
 };
 
 /* -----------------------------------------------------------------------------
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index 96857c508ee0..c4bb261dfcd9 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -563,6 +563,11 @@ static int pdev_probe(struct platform_device *pdev)
         ddev->dev_private = priv;
         platform_set_drvdata(pdev, ddev);
 
+        /* Get memory bandwidth limits */
+        if (priv->dispc_ops->get_memory_bandwidth_limit)
+                priv->max_bandwidth =
+                                priv->dispc_ops->get_memory_bandwidth_limit();
+
         omap_gem_init(ddev);
 
         ret = omap_modeset_init(ddev);
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.h b/drivers/gpu/drm/omapdrm/omap_drv.h
index 4bd1e9070b31..d404e8c56b61 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.h
+++ b/drivers/gpu/drm/omapdrm/omap_drv.h
@@ -83,6 +83,9 @@ struct omap_drm_private {
         spinlock_t wait_lock;           /* protects the wait_list */
         struct list_head wait_list;     /* list of omap_irq_wait */
         uint32_t irq_mask;              /* enabled irqs in addition to wait_list */
+
+        /* memory bandwidth limit if it is needed on the platform */
+        unsigned int max_bandwidth;
 };