backends/native: Read CRTC Gamma state from legacy and property APIs

If the device supports the atomic API the property based API is used to
write gamma updates and the legacy API is used in the non-atomic case.
The current state is read from the legacy API always though which can be
different from the property API. This commit always uses the correct API
to update the state.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2861>

src/backends/meta-crtc.c

@@ -194,6 +194,22 @@ meta_gamma_lut_new (int             size,
   return gamma;
 }
 
+MetaGammaLut *
+meta_gamma_lut_new_sized (int size)
+{
+  MetaGammaLut *gamma;
+
+  gamma = g_new0 (MetaGammaLut, 1);
+  *gamma = (MetaGammaLut) {
+    .size = size,
+    .red = g_new0 (uint16_t, size),
+    .green = g_new0 (uint16_t, size),
+    .blue = g_new0 (uint16_t, size),
+  };
+
+  return gamma;
+}
+
 MetaGammaLut *
 meta_gamma_lut_copy (const MetaGammaLut *gamma)
 {

src/backends/meta-crtc.h

@@ -99,6 +99,8 @@ MetaGammaLut * meta_gamma_lut_new (int             size,
                                    const uint16_t *green,
                                    const uint16_t *blue);
 
+MetaGammaLut * meta_gamma_lut_new_sized (int size);
+
 META_EXPORT_TEST
 MetaGammaLut * meta_gamma_lut_copy (const MetaGammaLut *gamma);
 

src/backends/native/meta-kms-crtc-private.h

@@ -30,6 +30,7 @@ typedef enum _MetaKmsCrtcProp
   META_KMS_CRTC_PROP_MODE_ID = 0,
   META_KMS_CRTC_PROP_ACTIVE,
   META_KMS_CRTC_PROP_GAMMA_LUT,
+  META_KMS_CRTC_PROP_GAMMA_LUT_SIZE,
   META_KMS_CRTC_N_PROPS
 } MetaKmsCrtcProp;
 

src/backends/native/meta-kms-crtc.c

@@ -24,6 +24,8 @@
 
 #include "backends/native/meta-kms-device-private.h"
 #include "backends/native/meta-kms-impl-device.h"
+#include "backends/native/meta-kms-impl-device-atomic.h"
+#include "backends/native/meta-kms-impl-device-simple.h"
 #include "backends/native/meta-kms-mode.h"
 #include "backends/native/meta-kms-update-private.h"
 
@@ -102,13 +104,69 @@ meta_kms_crtc_is_active (MetaKmsCrtc *crtc)
 }
 
 static void
-read_gamma_state (MetaKmsCrtc       *crtc,
-                  MetaKmsCrtcState  *crtc_state,
-                  MetaKmsImplDevice *impl_device,
-                  drmModeCrtc       *drm_crtc)
+read_crtc_gamma (MetaKmsCrtc       *crtc,
+                 MetaKmsCrtcState  *crtc_state,
+                 MetaKmsImplDevice *impl_device,
+                 drmModeCrtc       *drm_crtc)
 {
-  g_assert (crtc_state->gamma.value == NULL);
+  MetaKmsProp *prop_lut;
+  MetaKmsProp *prop_size;
+  uint64_t blob_id;
+  uint64_t lut_size;
+  int fd;
+  drmModePropertyBlobPtr blob;
+  int drm_lut_size;
+  struct drm_color_lut *drm_lut;
+  int i;
 
+  prop_lut = &crtc->prop_table.props[META_KMS_CRTC_PROP_GAMMA_LUT];
+  prop_size = &crtc->prop_table.props[META_KMS_CRTC_PROP_GAMMA_LUT_SIZE];
+
+  if (!prop_lut->prop_id || !prop_size->prop_id)
+    return;
+
+  blob_id = prop_lut->value;
+  if (blob_id == 0)
+    return;
+
+  lut_size = prop_size->value;
+  if (lut_size <= 0)
+    return;
+
+  fd = meta_kms_impl_device_get_fd (impl_device);
+  blob = drmModeGetPropertyBlob (fd, blob_id);
+  if (!blob)
+    return;
+
+  drm_lut_size = blob->length / sizeof (struct drm_color_lut);
+  if (drm_lut_size == 0)
+    {
+      drmModeFreePropertyBlob (blob);
+      return;
+    }
+
+  drm_lut = blob->data;
+
+  crtc_state->gamma.size = lut_size;
+  crtc_state->gamma.supported = TRUE;
+  crtc_state->gamma.value = meta_gamma_lut_new_sized (drm_lut_size);
+
+  for (i = 0; i < drm_lut_size; i++)
+    {
+      crtc_state->gamma.value->red[i] = drm_lut[i].red;
+      crtc_state->gamma.value->green[i] = drm_lut[i].green;
+      crtc_state->gamma.value->blue[i] = drm_lut[i].blue;
+    }
+
+  drmModeFreePropertyBlob (blob);
+}
+
+static void
+read_crtc_legacy_gamma (MetaKmsCrtc       *crtc,
+                        MetaKmsCrtcState  *crtc_state,
+                        MetaKmsImplDevice *impl_device,
+                        drmModeCrtc       *drm_crtc)
+{
   crtc_state->gamma.size = drm_crtc->gamma_size;
   crtc_state->gamma.supported = drm_crtc->gamma_size != 0;
   crtc_state->gamma.value = meta_gamma_lut_new (drm_crtc->gamma_size,
@@ -126,6 +184,23 @@ read_gamma_state (MetaKmsCrtc       *crtc,
                        crtc_state->gamma.value->blue);
 }
 
+static void
+read_gamma_state (MetaKmsCrtc       *crtc,
+                  MetaKmsCrtcState  *crtc_state,
+                  MetaKmsImplDevice *impl_device,
+                  drmModeCrtc       *drm_crtc)
+{
+  g_assert_null (crtc_state->gamma.value);
+
+  crtc_state->gamma.size = 0;
+  crtc_state->gamma.supported = FALSE;
+
+  if (META_IS_KMS_IMPL_DEVICE_ATOMIC (impl_device))
+    read_crtc_gamma (crtc, crtc_state, impl_device, drm_crtc);
+  else if (META_IS_KMS_IMPL_DEVICE_SIMPLE (impl_device))
+    read_crtc_legacy_gamma (crtc, crtc_state, impl_device, drm_crtc);
+}
+
 static gboolean
 gamma_equal (MetaKmsCrtcState *state,
              MetaKmsCrtcState *other_state)
@@ -349,6 +424,11 @@ init_properties (MetaKmsCrtc       *crtc,
           .name = "GAMMA_LUT",
           .type = DRM_MODE_PROP_BLOB,
         },
+      [META_KMS_CRTC_PROP_GAMMA_LUT_SIZE] =
+        {
+          .name = "GAMMA_LUT_SIZE",
+          .type = DRM_MODE_PROP_RANGE,
+        },
     }
   };
 }