STM32H753 Ethernet DMAMR register fails to reset when SWR bit is set

[AJose.2]

While setting up Ethernet connectivity on STM32H753, the HAL layer exited with HAL error during initialization. I found out that the SET_BIT(heth->Instance->DMAMR, ETH_DMAMR_SWR); fails to reset the register and the initialization exits with HAL error on timeout. I am using DP83848 as Ethernet PHY. I was able to verify that the link state is 100-Mbps Full Duplex and 25MHz clock is available as TX_CLK and RX_CLK. The PHY is used in MII mode.

[Piranha]

It the clocks are physically present on the respective MCU pins, then check the GPIO configuration for MII pins, MII/RMII configuration for the MAC and simple things like whether all 3 of the ETH MAC related clocks are enabled in RCC.

[Pavel A.]

@AJose.2​ Is the ETH driver the latest ST "reworked" version (HAL 1.10) or "pre-reworked", or anything custom?

If not the latest, could it be this issue?

Also, see this thread.

[Piranha]

Good point, but, as MII is the reset value and doesn't change anyway, it should not matter in this particular case.

[AJose.2]

The HAL version I'm using is V1.2.0. I tried (void)SYSCFG->PMCR; as suggested in https://github.com/STMicroelectronics/STM32CubeH7/issues/121 but didnt work. I also verified the clock configuration in RCC.

[Piranha]

On H7 only the latest version included in a CubeH7 v1.10 package is somewhat working. Previous versions, especially such an ancient one, are almost hopeless. Although the SWR bit depends on a simple things mentioned in previous comments and the issue should be simple.