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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 20.08.2021 14:18, Oleksandr Andrushchenko wrote:
> 
> 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?

No need to resubmit - I've replaced the original description and
committed the result.

Jan