[PATCH] ns16550: Fix DM serial operation with non-DM SPL

[Tom Rini]

On Tue, Jan 17, 2023 at 12:09:38PM +0000, Andre Przywara wrote:

> Commit 9591b63531fa ("Convert CONFIG_SYS_NS16550_MEM32 et al to Kconfig")
> moved some NS16550 configuration variables into Kconfig.
> Among those there is CONFIG_SYS_NS16550_REG_SIZE, which used to be only
> defined for SPL build runs, but now is always set (thanks for Kconfig).
> However this breaks the gating logic in ns16550.h, where we *override*
> this variable for DM build, as we learn this setting from the DT instead.
> 
> As a consequence, we did the register shift twice: once when building
> the register struct (as required for non-DM SPL builds), but then also
> again in the driver after we parsed the reg-shift DT property.
> 
> Change the logic to match what the comment says: only observe
> CONFIG_SYS_NS16550_REG_SIZE when not using DM, and ignore it otherwise.
> 
> This fixes U-Boot proper for all sunxi boards, since they are relying
> on this driver being build non-DM for the SPL, but DM for U-Boot proper.
> 
> Fixes: 9591b63531fa ("Convert CONFIG_SYS_NS16550_MEM32 et al to Kconfig")
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
> Hi,
> 
> this is admittedly a quick fix, to get sunxi booting again. This whole
> code around the register access looks somewhat bonkers, to be honest,
> but at the moment I don't have time to rework this.
> Another possible "quicker fix" would be use a separate variable for the
> register shift, so that we don't have to redefine a Kconfig variable.
> Another idea would be to get rid of the struct for the registers
> altogether, to remove the hacks about when to shift.
> 
> Cheers,
> Andre
> 
>  include/ns16550.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/include/ns16550.h b/include/ns16550.h
> index 243226fc3d9..e9e2aeedd16 100644
> --- a/include/ns16550.h
> +++ b/include/ns16550.h
> @@ -26,11 +26,12 @@
>  
>  #include <linux/types.h>
>  
> -#if CONFIG_IS_ENABLED(DM_SERIAL) && !defined(CONFIG_SYS_NS16550_REG_SIZE)
> +#if CONFIG_IS_ENABLED(DM_SERIAL)
>  /*
>   * For driver model we always use one byte per register, and sort out the
>   * differences in the driver
>   */
> +#undef CONFIG_SYS_NS16550_REG_SIZE
>  #define CONFIG_SYS_NS16550_REG_SIZE (-1)
>  #endif

Does:
https://patchwork.ozlabs.org/project/uboot/patch/20230110161946.3816866-5-trini@konsulko.com/
work for you as well?

-- 
Tom
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