stm32/eth: Restore CLK_SLEEP_ENABLE for packet reception during CPU sleep.

The CLK_SLEEP_ENABLE calls were removed during the restructure (commit
90297bc), leaving the driver dependent on the HAL default state.
While the default enables clocks during sleep, explicit configuration
is more robust and documents the requirement.

ETH clocks must remain enabled during CPU sleep (WFI) to allow the
peripheral to receive packets and generate interrupts, which is
necessary for DHCP and other network traffic.

Tested on NUCLEO_F429ZI: DHCP acquisition successful.

Signed-off-by: Andrew Leech <[email protected]>

Author: pi-anl

ports/stm32/eth.c

@@ -277,12 +277,26 @@ static int eth_mac_init(eth_t *self) {
     SYSCFG->PMC |= SYSCFG_PMC_MII_RMII_SEL;
     #endif
 
+    // Release ETH peripheral from reset and enable clocks during CPU sleep.
+    // Note: CLK_SLEEP_ENABLE means clocks stay ON during sleep (not OFF).
+    // Clocks must continue during sleep to allow the ETH peripheral to receive
+    // packets and generate interrupts when the CPU enters sleep mode (WFI),
+    // which is necessary for DHCP and other network traffic.
     #if defined(STM32H5)
     __HAL_RCC_ETH_RELEASE_RESET();
+    __HAL_RCC_ETH_CLK_SLEEP_ENABLE();
+    __HAL_RCC_ETHTX_CLK_SLEEP_ENABLE();
+    __HAL_RCC_ETHRX_CLK_SLEEP_ENABLE();
     #elif defined(STM32H7)
     __HAL_RCC_ETH1MAC_RELEASE_RESET();
+    __HAL_RCC_ETH1MAC_CLK_SLEEP_ENABLE();
+    __HAL_RCC_ETH1TX_CLK_SLEEP_ENABLE();
+    __HAL_RCC_ETH1RX_CLK_SLEEP_ENABLE();
     #else
     __HAL_RCC_ETHMAC_RELEASE_RESET();
+    __HAL_RCC_ETHMAC_CLK_SLEEP_ENABLE();
+    __HAL_RCC_ETHMACTX_CLK_SLEEP_ENABLE();
+    __HAL_RCC_ETHMACRX_CLK_SLEEP_ENABLE();
     #endif
 
     // Do a soft reset of the MAC core