Remove ESP_HAL_CONFIG_XTAL_FREQUENCY

Author: bugadani

esp-hal/CHANGELOG.md

@@ -34,6 +34,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Removed
 
+- The `ESP_HAL_CONFIG_XTAL_FREQUENCY` configuration option has been removed (#4517)
 
 ## [v1.0.0] - 2025-10-30
 

esp-hal/esp_config.yml

@@ -27,41 +27,6 @@ options:
   default:
     - value: false
 
-# Ideally, we should be able to set any clock frequency for any chip. However,
-# currently only the 32 and C2 implements any sort of configurability, and
-# the rest have a fixed clock frequency.
-- name: xtal-frequency
-  description: "The frequency of the crystal oscillator, in MHz. Set to `auto` to
-               automatically detect the frequency. `auto` may not be able to identify the clock
-               frequency in some cases. Also, configuring a specific frequency may increase
-               performance slightly."
-  default:
-    - if: 'chip == "esp32" || chip == "esp32c2"'
-      value: '"auto"'
-    - if: 'chip == "esp32c3" || chip == "esp32c6" || chip == "esp32s2" || chip == "esp32s3"'
-      value: '"40"'
-    - if: 'chip == "esp32h2"'
-      value: '"32"'
-  constraints:
-    - if: 'chip == "esp32" || chip == "esp32c2"'
-      type:
-        validator: enumeration
-        value:
-        - 'auto'
-        - '26'
-        - '40'
-    - if: 'chip == "esp32c3" || chip == "esp32c6" || chip == "esp32s2" || chip == "esp32s3"'
-      type:
-        validator: enumeration
-        value:
-        - '40'
-    - if: 'chip == "esp32h2"'
-      type:
-        validator: enumeration
-        value:
-        - '32'
-  active: 'chip == "esp32" || chip == "esp32c2"'
-
 - name: spi-address-workaround
   description: "Enables a workaround for the issue where SPI in
                half-duplex mode incorrectly transmits the address on a single line if the

esp-hal/src/clock/mod.rs

@@ -1116,51 +1116,30 @@ impl Clocks {
     #[cfg(systimer)]
     #[inline]
     pub(crate) fn xtal_freq() -> Rate {
-        if esp_config::esp_config_str!("ESP_HAL_CONFIG_XTAL_FREQUENCY") == "auto"
-            && let Some(clocks) = Self::try_get()
-        {
+        if let Some(clocks) = Self::try_get() {
             return clocks.xtal_clock;
         }
 
         Self::measure_xtal_frequency().frequency()
     }
 
-    #[cfg(not(esp32))] // unused
-    const fn xtal_frequency_from_config() -> Option<XtalClock> {
-        let frequency_conf = esp_config::esp_config_str!("ESP_HAL_CONFIG_XTAL_FREQUENCY");
-
-        for_each_soc_xtal_options!(
-            (all $( ($freq:literal) ),*) => {
-                paste::paste! {
-                    return match frequency_conf.as_bytes() {
-                        b"auto" => None,
+    #[cfg(not(esp32))]
+    fn measure_xtal_frequency() -> XtalClock {
+        cfg_if::cfg_if! {
+            if #[cfg(esp32h2)] {
+                XtalClock::_32M
+            } else if #[cfg(not(esp32c2))] {
+                XtalClock::_40M
+            } else {
+                // TODO: we should be able to read from a retention register, but probe-rs flashes a
+                // bootloader that assumes a frequency, instead of choosing a matching one.
+                let mhz = RtcClock::estimate_xtal_frequency();
 
-                        // If the frequency is a pre-set value for the chip, return the associated enum variant.
-                        $( _ if esp_config::esp_config_int_parse!(u32, frequency_conf) == $freq => Some(XtalClock::[<_ $freq M>]), )*
+                debug!("Working with a {}MHz crystal", mhz);
 
-                        _ => None,
-                    };
-                }
-            };
-        );
-    }
-
-    #[cfg(not(esp32))] // unused - the build-time config can be removed in favour of explicit configuration via esp_hal::init
-    fn measure_xtal_frequency() -> XtalClock {
-        if let Some(clock) = const { Self::xtal_frequency_from_config() } {
-            // Use the configured frequency
-            clock
-        } else if esp_config::esp_config_str!("ESP_HAL_CONFIG_XTAL_FREQUENCY") == "auto" {
-            // TODO: we should be able to read from a retention register, but probe-rs flashes a
-            // bootloader that assumes a frequency, instead of choosing a matching one.
-            let mhz = RtcClock::estimate_xtal_frequency();
-
-            debug!("Working with a {}MHz crystal", mhz);
-
-            // Try to guess the closest possible crystal value.
-            XtalClock::closest_from_mhz(mhz)
-        } else {
-            unreachable!("Invalid crystal frequency configured, this should not be possible.")
+                // Try to guess the closest possible crystal value.
+                XtalClock::closest_from_mhz(mhz)
+            }
         }
     }
 }