drm/nouveau: determine timing crystal freq from straps

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

1 files changed, 18 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_state.c b/drivers/gpu/drm/nouveau/nouveau_state.c
index f1047254e820..baaecf10a585 100644
--- a/drivers/gpu/drm/nouveau/nouveau_state.c
+++ b/drivers/gpu/drm/nouveau/nouveau_state.c
@@ -984,7 +984,7 @@ static int nouveau_remove_conflicting_drivers(struct drm_device *dev)
 int nouveau_load(struct drm_device *dev, unsigned long flags)
 {
         struct drm_nouveau_private *dev_priv;
-        uint32_t reg0;
+        uint32_t reg0, strap;
         resource_size_t mmio_start_offs;
         int ret;
 
@@ -1074,6 +1074,23 @@ int nouveau_load(struct drm_device *dev, unsigned long flags)
         NV_INFO(dev, "Detected an NV%2x generation card (0x%08x)\n",
                 dev_priv->card_type, reg0);
 
+        /* determine frequency of timing crystal */
+        strap = nv_rd32(dev, 0x101000);
+        if ( dev_priv->chipset < 0x17 ||
+            (dev_priv->chipset >= 0x20 && dev_priv->chipset <= 0x25))
+                strap &= 0x00000040;
+        else
+                strap &= 0x00400040;
+
+        switch (strap) {
+        case 0x00000000: dev_priv->crystal = 13500; break;
+        case 0x00000040: dev_priv->crystal = 14318; break;
+        case 0x00400000: dev_priv->crystal = 27000; break;
+        case 0x00400040: dev_priv->crystal = 25000; break;
+        }
+
+        NV_DEBUG(dev, "crystal freq: %dKHz\n", dev_priv->crystal);
+
         /* Determine whether we'll attempt acceleration or not, some
          * cards are disabled by default here due to them being known
          * non-functional, or never been tested due to lack of hw.