drm/i915: fix panel fitting filter coefficient select for Ironlake

Must set filter selection as hardcoded coefficients for medium 3x3
filtering, which matches vbios setting for Ironlake.

This fixes display corrupt issue on HP arrandale with new vbios.

Cc: Stable Team <stable@kernel.org>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Eric Anholt <eric@anholt.net>

2 files changed, 6 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index cd0ffa015c27..78f336e00836 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -2039,6 +2039,11 @@
 #define PFA_CTL_1               0x68080
 #define PFB_CTL_1               0x68880
 #define  PF_ENABLE              (1<<31)
+#define  PF_FILTER_MASK         (3<<23)
+#define  PF_FILTER_PROGRAMMED   (0<<23)
+#define  PF_FILTER_MED_3x3      (1<<23)
+#define  PF_FILTER_EDGE_ENHANCE (2<<23)
+#define  PF_FILTER_EDGE_SOFTEN  (3<<23)
 #define PFA_WIN_SZ              0x68074
 #define PFB_WIN_SZ              0x68874
 #define PFA_WIN_POS             0x68070
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index db4c38700951..e189fd6dedcf 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1515,7 +1515,7 @@ static void igdng_crtc_dpms(struct drm_crtc *crtc, int mode)
                 /* Enable panel fitting for LVDS */
                 if (intel_pipe_has_type(crtc, INTEL_OUTPUT_LVDS)) {
                         temp = I915_READ(pf_ctl_reg);
-                        I915_WRITE(pf_ctl_reg, temp | PF_ENABLE);
+                        I915_WRITE(pf_ctl_reg, temp | PF_ENABLE | PF_FILTER_MED_3x3);
 
                         /* currently full aspect */
                         I915_WRITE(pf_win_pos, 0);