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

[Oleksandr Andrushchenko <andr2000@xxxxxxxxx>]

On 20.08.21 15:07, Jan Beulich wrote:
> 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 ...
Ok, the full story is that I am building this with PCI passthrough support on 
Arm,

so yes, you are obviously correct here and "Fixes" tag does not apply.

I will remove it.

> > --- 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>
I can put the following description:

    ns16550: Properly gate Exar PCIe UART cards support

    Arm is about to get PCI passthrough support which means CONFIG_HAS_PCI
    will be enabled, so this code will fail as Arm 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);
          |     ^~~~~~~~~~~~~~~~~~~~~~~~~

    Fix this by gating Exar PCIe UART cards support with the above in mind.

Will this be ok?

Can I keep your rb tag with this description?

> As an aside - please follow patch submission guidelines: Patches go
> To the list, with maintainers (and perhaps other relevant folks) on Cc.
Sure, sorry about that
> Jan
Thank you,

Oleksandr