feat: add per output max-bpc config and ipc action

List current max-bpc values in outputs.

fix: remove 16 bpc and change default behaviour

feat(ipc): add max_bpc and format to output

fix: bpc on output config change

docs: add bpc to Outputs

feat: use atomic commits for connector properties

fix: drm `value_type` breaking change

fix: minor changes based on PR review

Rename bpc to max-bpc.

Add max-bpc output action.

refactor: add set_connector_properties

Fix niri-config parse test.

fix: bail when outside valid max bpc range

niri-ipc/src/lib.rs

@@ -1097,6 +1097,12 @@ pub enum OutputAction {
         #[cfg_attr(feature = "clap", command(flatten))]
         vrr: VrrToSet,
     },
+    /// Set the maximum bits per channel (bit depth).
+    MaxBpc {
+        /// Maximum bits per channel to set.
+        #[cfg_attr(feature = "clap", arg())]
+        max_bpc: MaxBpc,
+    },
 }
 
 /// Output mode to set.
@@ -1228,6 +1234,8 @@ pub struct Output {
     ///
     /// `None` if the output is not mapped to any logical output (for example, if it is disabled).
     pub logical: Option<LogicalOutput>,
+    /// Maximum bits per channel (bit depth), if known.
+    pub max_bpc: Option<u8>,
 }
 
 /// Output mode.
@@ -1291,6 +1299,32 @@ pub enum Transform {
     Flipped270,
 }
 
+/// Output maximum bits per channel.
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, Default)]
+#[cfg_attr(feature = "clap", derive(clap::ValueEnum))]
+#[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
+pub enum MaxBpc {
+    /// 6-bit.
+    #[serde(rename = "6")]
+    _6 = 6,
+    /// 8-bit.
+    #[default]
+    #[serde(rename = "8")]
+    _8 = 8,
+    /// 10-bit.
+    #[serde(rename = "10")]
+    _10 = 10,
+    /// 12-bit.
+    #[serde(rename = "12")]
+    _12 = 12,
+    /// 14-bit.
+    #[serde(rename = "14")]
+    _14 = 14,
+    /// 16-bit.
+    #[serde(rename = "16")]
+    _16 = 16,
+}
+
 /// Toplevel window.
 #[derive(Serialize, Deserialize, Debug, Clone)]
 #[cfg_attr(feature = "json-schema", derive(schemars::JsonSchema))]
@@ -1868,6 +1902,30 @@ impl FromStr for Transform {
     }
 }
 
+impl TryFrom<u8> for MaxBpc {
+    type Error = &'static str;
+
+    fn try_from(value: u8) -> Result<Self, Self::Error> {
+        match value {
+            6 => Ok(MaxBpc::_6),
+            8 => Ok(MaxBpc::_8),
+            10 => Ok(MaxBpc::_10),
+            12 => Ok(MaxBpc::_12),
+            14 => Ok(MaxBpc::_14),
+            16 => Ok(MaxBpc::_16),
+            _ => Err("invalid max-bpc, can be 6, 8, 10, 12, 14, 16"),
+        }
+    }
+}
+
+impl FromStr for MaxBpc {
+    type Err = &'static str;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        Self::try_from(s.parse::<u8>().unwrap_or_default())
+    }
+}
+
 impl FromStr for Layer {
     type Err = &'static str;