[PATCH] arm: am33xx: Fix early debug UART initialization

[Simon Glass]

Hi Felix,

On Thu, 24 Feb 2022 at 03:01, Felix Brack <fb at ltec.ch> wrote:
>
> Hello Simon,
>
> On 23.02.22 23:58, Simon Glass wrote:
> > Hi Felix,
> >
> > On Mon, 14 Feb 2022 at 09:57, Felix Brack <fb at ltec.ch> wrote:
> >>
> >> The changes from commit 0dba45864b2a ("arm: Init the debug UART")
> >> prevent the early debug UART from being initialized correctly.
> >> By adding a new SoC specific early UART initialization function this
> >
> > SoC-specific
> >
> > You need the hyphen for this to make sense, since you are creating an adjective.
> >
> >> patch provides a generic location to add the required code. This code
> >> has to be SoC and not board specific.
> >
> > board-specific
> >
> >> For the am33xx SoCs the fix consist of configuring early clocks.
> >>
> >> Signed-off-by: Felix Brack <fb at ltec.ch>
> >> ---
> >>
> >>  arch/arm/mach-omap2/am33xx/board.c |  7 +++++++
> >>  drivers/serial/Kconfig             | 13 +++++++++++++
> >>  include/debug_uart.h               | 15 +++++++++++++++
> >>  3 files changed, 35 insertions(+)
> >
> > More nits below.
> >
> > Reviewed-by: Simon Glass <sjg at chromium.org>
> >
> >>
> >> diff --git a/arch/arm/mach-omap2/am33xx/board.c b/arch/arm/mach-omap2/am33xx/board.c
> >> index c44667668e..a7f0445b93 100644
> >> --- a/arch/arm/mach-omap2/am33xx/board.c
> >> +++ b/arch/arm/mach-omap2/am33xx/board.c
> >> @@ -604,3 +604,10 @@ int arch_cpu_init_dm(void)
> >>  #endif
> >>         return 0;
> >>  }
> >> +
> >> +#if IS_ENABLED(CONFIG_DEBUG_UART_SOC_INIT)
> >> +void soc_debug_uart_init(void)
> >> +{
> >> +       setup_early_clocks();
> >> +}
> >> +#endif
> >> diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
> >> index 345d1881f5..3da4064d35 100644
> >> --- a/drivers/serial/Kconfig
> >> +++ b/drivers/serial/Kconfig
> >> @@ -490,6 +490,19 @@ config DEBUG_UART_SHIFT
> >>           value. Use this value to specify the shift to use, where 0=byte
> >>           registers, 2=32-bit word registers, etc.
> >>
> >> +config DEBUG_UART_SOC_INIT
> >> +       bool "Enable SoC-specific debug UART init"
> >> +       depends on DEBUG_UART
> >> +       help
> >> +         Boards using the same SoC might require some common settings before
> >> +         the debug UART can be used. The board specific board_debug_uart_init()
> >> +         is not the right place for such common settings as they would apply
> >> +         to a specific board only instead of all boards using the same SoC.
> >> +         When this option is enabled, the SoC specific function
> >> +         soc_debug_uart_init() will be called when debug_uart_init() is called.
> >> +         You can put any code here that is needed to set up the UART ready for
> >> +         use.
> >
> > Please mention the order in which the board and SoC functions are called.
> >
> >> +
> >>  config DEBUG_UART_BOARD_INIT
> >>         bool "Enable board-specific debug UART init"
> >>         depends on DEBUG_UART
> >> diff --git a/include/debug_uart.h b/include/debug_uart.h
> >> index 714b369e6f..ebc84c44cd 100644
> >> --- a/include/debug_uart.h
> >> +++ b/include/debug_uart.h
> >> @@ -42,6 +42,12 @@
> >>   * - Immediately afterwards, add DEBUG_UART_FUNCS to define the rest of the
> >>   *     functionality (printch(), etc.)
> >>   *
> >> + * If your SoC needs additional init for the UART to work, enable
> >> + * CONFIG_DEBUG_UART_SOC_INIT and write a function called
> >> + * soc_debug_uart_init() to perform that init. When debug_uart_init() is
> >> + * called, the init will happen automatically. Board specific code does not
> >> + * go here, see board_debug_uart_init() below.
> >
> > Again please fix your specifics.
> >
> >
> >> + *
> >>   * If your board needs additional init for the UART to work, enable
> >>   * CONFIG_DEBUG_UART_BOARD_INIT and write a function called
> >>   * board_debug_uart_init() to perform that init. When debug_uart_init() is
> >> @@ -61,6 +67,14 @@
> >>   */
> >>  void debug_uart_init(void);
> >>
> >> +#ifdef CONFIG_DEBUG_UART_SOC_INIT
> >> +void soc_debug_uart_init(void);
> >> +#else
> >> +static inline void soc_debug_uart_init(void)
> >> +{
> >> +}
> >> +#endif
> >> +
> >>  #ifdef CONFIG_DEBUG_UART_BOARD_INIT
> >>  void board_debug_uart_init(void);
> >>  #else
> >> @@ -192,6 +206,7 @@ void printdec(unsigned int value);
> >>  \
> >>         void debug_uart_init(void) \
> >>         { \
> >> +               soc_debug_uart_init(); \
> >>                 board_debug_uart_init(); \
> >>                 _debug_uart_init(); \
> >>                 _DEBUG_UART_ANNOUNCE \
> >> --
> >> 2.25.1
> >>
> Thanks for the review! However it looks like this patch will never get
> applied. If I'm wrong please let me know and I'll be happy to send a
> fixed version.

OK, I suppose it can wait until another board comes along that needs it.

Regards,
Simon