Re: [PATCH] ns16550: Properly gate Exar PCIe UART cards support

[Jan Beulich <jbeulich@xxxxxxxx>]

On 20.08.2021 13:54, Oleksandr Andrushchenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> 
> This fixes Arm build which doesn't have ns16550 PCI support.
> 
> ns16550.c:313:5: error: implicit declaration of function 
> 'enable_exar_enhanced_bits' [-Werror=implicit-function-declaration]
>   313 |     enable_exar_enhanced_bits(uart);
>       |     ^~~~~~~~~~~~~~~~~~~~~~~~~

This can't be the full story - both Arm32 and Arm64 build fine for me.
In fact I can't find any "select HAS_PCI" outside of x86'es subtree.

> Fixes: 5ffd37db2ff6 ("ns16550: add Exar PCIe UART cards support")

IOW this tag is wrong, no matter that I agree that ...

> --- a/xen/drivers/char/ns16550.c
> +++ b/xen/drivers/char/ns16550.c
> @@ -308,7 +308,7 @@ static void ns16550_setup_preirq(struct ns16550 *uart)
>      /* Handle the DesignWare 8250 'busy-detect' quirk. */
>      handle_dw_usr_busy_quirk(uart);
>  
> -#ifdef CONFIG_HAS_PCI
> +#ifdef NS16550_PCI
>      /* Enable Exar "Enhanced function bits" */
>      enable_exar_enhanced_bits(uart);
>  #endif

... this change is wanted, but just for consistency for now. If you
can supply an improved / accurate description, I'll be happy to commit
this with
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

As an aside - please follow patch submission guidelines: Patches go
To the list, with maintainers (and perhaps other relevant folks) on Cc.

Jan