drm/i915: Allow downscale factor of <3.0 on glk+ for all formats

Bspec says that glk+ max downscale factor is <3.0 for all pixel formats.
Older platforms had a max of <2.0 for NV12. Update the code to deal with
this.

Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190913193157.9556-3-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 276adc3..1a72706 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -14556,7 +14556,7 @@ skl_max_scale(const struct intel_crtc_state *crtc_state,
 {
        struct intel_crtc *crtc = to_intel_crtc(crtc_state->base.crtc);
        struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-       int max_scale, mult;
+       int max_scale;
        int crtc_clock, max_dotclk, tmpclk1, tmpclk2;
 
        if (!crtc_state->base.enable)
@@ -14577,8 +14577,11 @@ skl_max_scale(const struct intel_crtc_state *crtc_state,
         *            or
         *    cdclk/crtc_clock
         */
-       mult = drm_format_info_is_yuv_semiplanar(format) ? 2 : 3;
-       tmpclk1 = (1 << 16) * mult - 1;
+       if (INTEL_GEN(dev_priv) >= 10 || IS_GEMINILAKE(dev_priv) ||
+           !drm_format_info_is_yuv_semiplanar(format))
+               tmpclk1 = 0x30000 - 1;
+       else
+               tmpclk1 = 0x20000 - 1;
        tmpclk2 = (1 << 8) * ((max_dotclk << 8) / crtc_clock);
        max_scale = min(tmpclk1, tmpclk2);