drm/tilcdc: adding some more devicetree config

Adding support for max-pixelclock and max-width device tree
entries. As some devices that use the tilcdc hardware module
have restrictions on the allowed/tested values.  Also update DT
bindings document to reflect new parameters.

Signed-off-by: Darren Etheridge <detheridge@ti.com>
Acked-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

3 files changed, 57 insertions, 3 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 5b68fe59e437..b5b865f4f92b 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -443,10 +443,29 @@ int tilcdc_crtc_mode_valid(struct drm_crtc *crtc, struct drm_display_mode *mode)
         if (mode->vdisplay > 2048)
                 return MODE_VIRTUAL_Y;
 
+        /*
+         * some devices have a maximum allowed pixel clock
+         * configured from the DT
+         */
+        if (mode->clock > priv->max_pixelclock) {
+                DBG("Pruning mode, pixel clock too high");
+                return MODE_CLOCK_HIGH;
+        }
+
+        /*
+         * some devices further limit the max horizontal resolution
+         * configured from the DT
+         */
+        if (mode->hdisplay > priv->max_width)
+                return MODE_BAD_WIDTH;
+
         /* filter out modes that would require too much memory bandwidth: */
-        bandwidth = mode->hdisplay * mode->vdisplay * drm_mode_vrefresh(mode);
-        if (bandwidth > priv->max_bandwidth)
+        bandwidth = mode->hdisplay * mode->vdisplay *
+                drm_mode_vrefresh(mode);
+        if (bandwidth > priv->max_bandwidth) {
+                DBG("Pruning mode, exceeds defined bandwidth limit");
                 return MODE_BAD;
+        }
 
         return MODE_OK;
 }
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index f2a6528ddef0..1e8f273f7c8b 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -212,7 +212,20 @@ static int tilcdc_load(struct drm_device *dev, unsigned long flags)
 #endif
 
         if (of_property_read_u32(node, "max-bandwidth", &priv->max_bandwidth))
-                priv->max_bandwidth = 1280 * 1024 * 60;
+                priv->max_bandwidth = TILCDC_DEFAULT_MAX_BANDWIDTH;
+
+        DBG("Maximum Bandwidth Value %d", priv->max_bandwidth);
+
+        if (of_property_read_u32(node, "ti,max-width", &priv->max_width))
+                priv->max_width = TILCDC_DEFAULT_MAX_WIDTH;
+
+        DBG("Maximum Horizontal Pixel Width Value %dpixels", priv->max_width);
+
+        if (of_property_read_u32(node, "ti,max-pixelclock",
+                                        &priv->max_pixelclock))
+                priv->max_pixelclock = TILCDC_DEFAULT_MAX_PIXELCLOCK;
+
+        DBG("Maximum Pixel Clock Value %dKHz", priv->max_pixelclock);
 
         pm_runtime_enable(dev->dev);
 
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
index 090684341fdb..66df316ca434 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
@@ -34,6 +34,18 @@
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_fb_cma_helper.h>
 
+/* Defaulting to pixel clock defined on AM335x */
+#define TILCDC_DEFAULT_MAX_PIXELCLOCK  126000
+/* Defaulting to max width as defined on AM335x */
+#define TILCDC_DEFAULT_MAX_WIDTH  2048
+/*
+ * This may need some tweaking, but want to allow at least 1280x1024@60
+ * with optimized DDR & EMIF settings tweaked 1920x1080@24 appears to
+ * be supportable
+ */
+#define TILCDC_DEFAULT_MAX_BANDWIDTH  (1280*1024*60)
+
+
 struct tilcdc_drm_private {
         void __iomem *mmio;
 
@@ -43,6 +55,16 @@ struct tilcdc_drm_private {
 
         /* don't attempt resolutions w/ higher W * H * Hz: */
         uint32_t max_bandwidth;
+        /*
+         * Pixel Clock will be restricted to some value as
+         * defined in the device datasheet measured in KHz
+         */
+        uint32_t max_pixelclock;
+        /*
+         * Max allowable width is limited on a per device basis
+         * measured in pixels
+         */
+        uint32_t max_width;
 
         /* register contents saved across suspend/resume: */
         u32 saved_register[12];