[PATCH] board: atmel: sama5d2_wlsom1_ek: Fix spurious serial output

[PATCH] board: atmel: sama5d2_wlsom1_ek: Fix spurious serial output

[Fabio Estevam]

From: Fabio Estevam <festevam@denx.de>

Currently, there are always some spurious characters showing up
right before SPL banner is shown:

RomBOOT
���=������
U-Boot SPL 2025.04-rc5-00023-g9ed4e2c45f25 (Apr 03 2025 - 23:23:17 -0300)
Trying to boot from MMC1

<debug_uart>
...

Fix this problem by removing the redundant UART iomux and clock
initialization from the board code, as they are handled by DM code.

Signed-off-by: Fabio Estevam <festevam@denx.de>
---
 board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c b/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c
index 04de1257eca0..a0ecc4f42a90 100644
--- a/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c
+++ b/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c
@@ -41,17 +41,8 @@ int board_late_init(void)
 #endif
 
 #ifdef CONFIG_DEBUG_UART_BOARD_INIT
-static void board_uart0_hw_init(void)
-{
-	atmel_pio4_set_c_periph(AT91_PIO_PORTB, 26, ATMEL_PIO_PUEN_MASK);	/* URXD0 */
-	atmel_pio4_set_c_periph(AT91_PIO_PORTB, 27, 0);				/* UTXD0 */
-
-	at91_periph_clk_enable(ATMEL_ID_UART0);
-}
-
 void board_debug_uart_init(void)
 {
-	board_uart0_hw_init();
 }
 #endif
 
-- 
2.34.1

Re: [PATCH] board: atmel: sama5d2_wlsom1_ek: Fix spurious serial output

[Eugen Hristev]

On 4/4/25 05:36, Fabio Estevam wrote:
> From: Fabio Estevam <festevam@denx.de>
> 
> Currently, there are always some spurious characters showing up
> right before SPL banner is shown:
> 
> RomBOOT
> ���=������
> U-Boot SPL 2025.04-rc5-00023-g9ed4e2c45f25 (Apr 03 2025 - 23:23:17 -0300)
> Trying to boot from MMC1
> 
> <debug_uart>
> ...
> 
> Fix this problem by removing the redundant UART iomux and clock
> initialization from the board code, as they are handled by DM code.

If it's a redundant initialization, how does that lead to spurious
characters ?
My take on this is that the UART is initialized too late, and the lines
are floating for some time.
... or wrongly initialized vs baud, etc, for a certain amount of time.

> 
> Signed-off-by: Fabio Estevam <festevam@denx.de>
> ---
>  board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c b/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c
> index 04de1257eca0..a0ecc4f42a90 100644
> --- a/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c
> +++ b/board/atmel/sama5d27_wlsom1_ek/sama5d27_wlsom1_ek.c
> @@ -41,17 +41,8 @@ int board_late_init(void)
>  #endif
>  
>  #ifdef CONFIG_DEBUG_UART_BOARD_INIT
> -static void board_uart0_hw_init(void)
> -{
> -	atmel_pio4_set_c_periph(AT91_PIO_PORTB, 26, ATMEL_PIO_PUEN_MASK);	/* URXD0 */
> -	atmel_pio4_set_c_periph(AT91_PIO_PORTB, 27, 0);				/* UTXD0 */
> -
> -	at91_periph_clk_enable(ATMEL_ID_UART0);
> -}
> -
>  void board_debug_uart_init(void)
>  {
> -	board_uart0_hw_init();
>  }
>  #endif
>