Re: [PATCH v5 1/9] drivers/char: separate dbgp=xhci to dbc=xhci option

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.08.2022 13:46, Marek Marczykowski-Górecki wrote:
> On Thu, Aug 25, 2022 at 05:44:54PM +0200, Jan Beulich wrote:
>> On 22.08.2022 17:27, Marek Marczykowski-Górecki wrote:
>>> This allows configuring EHCI and XHCI consoles separately,
>>> simultaneously.
>>>
>>> Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
>>
>> But was I maybe confused, and much less of a change would suffice? After
>> all ...
>>
>>> --- a/xen/drivers/char/xhci-dbc.c
>>> +++ b/xen/drivers/char/xhci-dbc.c
>>> @@ -1058,9 +1058,9 @@ static struct xhci_dbc_ctx ctx __aligned(16);
>>>  static uint8_t out_wrk_buf[DBC_WORK_RING_CAP];
>>>  static struct xhci_string_descriptor str_buf[DBC_STRINGS_COUNT];
>>>  
>>> -static char __initdata opt_dbgp[30];
>>> +static char __initdata opt_dbc[30];
>>>  
>>> -string_param("dbgp", opt_dbgp);
>>> +string_param("dbc", opt_dbc);
>>>  
>>>  void __init xhci_dbc_uart_init(void)
>>>  {
>>> @@ -1068,25 +1068,25 @@ void __init xhci_dbc_uart_init(void)
>>>      struct dbc *dbc = &uart->dbc;
>>>      const char *e;
>>>  
>>> -    if ( strncmp(opt_dbgp, "xhci", 4) )
>>> +    if ( strncmp(opt_dbc, "xhci", 4) )
>>>          return;
>>
>> ... this already avoids mixing up who's going to parse what. So right
>> now I think that ...
>>
>>> @@ -1102,7 +1102,7 @@ void __init xhci_dbc_uart_init(void)
>>>      dbc->dbc_str = str_buf;
>>>  
>>>      if ( dbc_open(dbc) )
>>> -        serial_register_uart(SERHND_DBGP, &dbc_uart_driver, &dbc_uart);
>>> +        serial_register_uart(SERHND_DBC, &dbc_uart_driver, &dbc_uart);
>>>  }
>>
>> ... this and other SERHND_* related changes are enough, and there's no
>> need for a separate "dbc=" option.
> 
> But then you wouldn't be able to configure "dbgp=ehci dbgp=xhci" as
> one would override the other, no?

Not as long as both use string_param(), true. They'd need to both become
custom_param(), doing at least some basic parsing right away.

But using two such options at the same time isn't of interest anyway
without your multiple-serial-consoles change, so possibly not of
immediate need (unless someone comes forward expressing interest and
actually approving that change of yours).

Jan