drm/i915: No panel fitter on 830M or non-mobile gen2/3 platforms

PFIT_CONTROL doesn't exist on 830M, so avoid reading it in
i9xx_get_pfit_config().

Also assume that only mobile gen2/3 chipsets have a panel fitter. This
matches the documentation, but I didn't have real hardware to verify.

Gen4 docmentation is a bit inconsistent, but experimenetation on my
LPT machine suggests that the panel fitter is available on non-mobile
gen4 platforms. At least on this machine panel fitter appears works
just fine even on VGA output.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

2 files changed, 4 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index fe2d71a1c39e..db1e0a4eb359 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -5439,6 +5439,9 @@ static void i9xx_get_pfit_config(struct intel_crtc *crtc,
         struct drm_i915_private *dev_priv = dev->dev_private;
         uint32_t tmp;
 
+        if (INTEL_INFO(dev)->gen <= 3 && (IS_I830(dev) || !IS_MOBILE(dev)))
+                return;
+
         tmp = I915_READ(PFIT_CONTROL);
         if (!(tmp & PFIT_ENABLE))
                 return;
diff --git a/drivers/gpu/drm/i915/intel_overlay.c b/drivers/gpu/drm/i915/intel_overlay.c
index a98a990fbab3..a759ecdb7a6e 100644
--- a/drivers/gpu/drm/i915/intel_overlay.c
+++ b/drivers/gpu/drm/i915/intel_overlay.c
@@ -1005,7 +1005,7 @@ static int intel_panel_fitter_pipe(struct drm_device *dev)
         u32  pfit_control;
 
         /* i830 doesn't have a panel fitter */
-        if (IS_I830(dev))
+        if (INTEL_INFO(dev)->gen <= 3 && (IS_I830(dev) || !IS_MOBILE(dev)))
                 return -1;
 
         pfit_control = I915_READ(PFIT_CONTROL);