drm/i915: Add support for half float framebuffers for ivb+ sprites

ivb+ supports fp16 pixel formats on the sprite planes planes. Expose
that capability.

On ivb/hsw fp16 scanout is slightly busted. The output from the plane
will have 1/4 the expected value. For the sprite plane we can fix that
up with the plane gamma unit. This was fixed on bdw.

v2: Rebase on top of icl fp16
    Split the ivb+ sprite birs into a separate patch
v3: Move ivb_need_sprite_gamma() check one level up so that
    we don't waste time programming garbage into he gamma registers

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/20191015193035.25982-10-ville.syrjala@linux.intel.com

diff --git a/drivers/gpu/drm/i915/display/intel_sprite.c b/drivers/gpu/drm/i915/display/intel_sprite.c
index e844229..db1e2dc 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_sprite.c
+++ b/drivers/gpu/drm/i915/display/intel_sprite.c
@@ -1316,6 +1316,16 @@ static u32 ivb_sprite_ctl_crtc(const struct intel_crtc_state *crtc_state)
        return sprctl;
 }
 
+static bool ivb_need_sprite_gamma(const struct intel_plane_state *plane_state)
+{
+       struct drm_i915_private *dev_priv =
+               to_i915(plane_state->base.plane->dev);
+       const struct drm_framebuffer *fb = plane_state->base.fb;
+
+       return fb->format->cpp[0] == 8 &&
+               (IS_IVYBRIDGE(dev_priv) || IS_HASWELL(dev_priv));
+}
+
 static u32 ivb_sprite_ctl(const struct intel_crtc_state *crtc_state,
                          const struct intel_plane_state *plane_state)
 {
@@ -1338,6 +1348,12 @@ static u32 ivb_sprite_ctl(const struct intel_crtc_state *crtc_state,
        case DRM_FORMAT_XRGB8888:
                sprctl |= SPRITE_FORMAT_RGBX888;
                break;
+       case DRM_FORMAT_XBGR16161616F:
+               sprctl |= SPRITE_FORMAT_RGBX161616 | SPRITE_RGB_ORDER_RGBX;
+               break;
+       case DRM_FORMAT_XRGB16161616F:
+               sprctl |= SPRITE_FORMAT_RGBX161616;
+               break;
        case DRM_FORMAT_YUYV:
                sprctl |= SPRITE_FORMAT_YUV422 | SPRITE_YUV_ORDER_YUYV;
                break;
@@ -1355,7 +1371,8 @@ static u32 ivb_sprite_ctl(const struct intel_crtc_state *crtc_state,
                return 0;
        }
 
-       sprctl |= SPRITE_INT_GAMMA_DISABLE;
+       if (!ivb_need_sprite_gamma(plane_state))
+               sprctl |= SPRITE_INT_GAMMA_DISABLE;
 
        if (plane_state->base.color_encoding == DRM_COLOR_YCBCR_BT709)
                sprctl |= SPRITE_YUV_TO_RGB_CSC_FORMAT_BT709;
@@ -1377,12 +1394,26 @@ static u32 ivb_sprite_ctl(const struct intel_crtc_state *crtc_state,
        return sprctl;
 }
 
-static void ivb_sprite_linear_gamma(u16 gamma[18])
+static void ivb_sprite_linear_gamma(const struct intel_plane_state *plane_state,
+                                   u16 gamma[18])
 {
-       int i;
+       int scale, i;
 
-       for (i = 0; i < 17; i++)
-               gamma[i] = (i << 10) / 16;
+       /*
+        * WaFP16GammaEnabling:ivb,hsw
+        * "Workaround : When using the 64-bit format, the sprite output
+        *  on each color channel has one quarter amplitude. It can be
+        *  brought up to full amplitude by using sprite internal gamma
+        *  correction, pipe gamma correction, or pipe color space
+        *  conversion to multiply the sprite output by four."
+        */
+       scale = 4;
+
+       for (i = 0; i < 16; i++)
+               gamma[i] = min((scale * i << 10) / 16, (1 << 10) - 1);
+
+       gamma[i] = min((scale * i << 10) / 16, 1 << 10);
+       i++;
 
        gamma[i] = 3 << 10;
        i++;
@@ -1396,7 +1427,10 @@ static void ivb_update_gamma(const struct intel_plane_state *plane_state)
        u16 gamma[18];
        int i;
 
-       ivb_sprite_linear_gamma(gamma);
+       if (!ivb_need_sprite_gamma(plane_state))
+               return;
+
+       ivb_sprite_linear_gamma(plane_state, gamma);
 
        /* FIXME these register are single buffered :( */
        for (i = 0; i < 16; i++)
@@ -2551,6 +2585,8 @@ static bool snb_sprite_format_mod_supported(struct drm_plane *_plane,
        switch (format) {
        case DRM_FORMAT_XRGB8888:
        case DRM_FORMAT_XBGR8888:
+       case DRM_FORMAT_XRGB16161616F:
+       case DRM_FORMAT_XBGR16161616F:
        case DRM_FORMAT_YUYV:
        case DRM_FORMAT_YVYU:
        case DRM_FORMAT_UYVY: