Re: [Xen-devel] [PATCH 2/4] ns16550: enable Pericom controller support

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.03.16 at 17:52, <konrad.wilk@xxxxxxxxxx> wrote:
> On Tue, Mar 08, 2016 at 01:48:05AM -0700, Jan Beulich wrote:
>> >>> On 07.03.16 at 23:04, <konrad.wilk@xxxxxxxxxx> wrote:
>> > Hmm, if it was some other PCI based serial card like:
>> > 
>> > 01:05.0 Serial controller: NetMos Technology PCI 9835 Multi-I/O
>> > Controller (rev 01) (prog-if 02 [16550])
>> >         Subsystem: LSI Logic / Symbios Logic Device 0001
>> >         Flags: medium devsel, IRQ 20
>> >         I/O ports at e050 [size=8]
>> >         I/O ports at e040 [size=8]
>> >         I/O ports at e030 [size=8]
>> >         I/O ports at e020 [size=8]
>> >         I/O ports at e010 [size=8]
>> >         I/O ports at e000 [size=16]
>> > 
>> > With 'com1=115200,8n1,pci' and 'com2=115200,8n1,pci' then the first loop
>> > would find the device. The second loop would decrement idx (1) by 1 and
>> > continue.. which would make it go search for another device.
>> > 
>> > I hadn't tested this patch on the above device but I believe it used
>> > to work with the com1 and com2 going throught it - while with the new code
>> > it won't?
>> 
>> That's the !bar0 case, and hence the code in the loop over
> 
> You mean:
> 
>                                param += uart_config[i].param;
> +                        if ( !param->bar0 )
> +                        {
> +                            bar_idx = idx;
> +                            port_idx = 0;
> +                        }
> ?
> 
> The device in question (NetMos) is not on the uart_config list at all
> so we won't get inside this loop.

Well, for devices not on the list it's undetermined anyway whether
they would happen to work - we just can't get it right for all possible
cases. Someone truly caring about them working should submit a
patch adding them to the list.

Jan


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