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

[Konrad Rzeszutek Wilk <konrad@xxxxxxxxxx>]

On Wed, Mar 09, 2016 at 10:01:08AM -0700, Jan Beulich wrote:
> >>> 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

Wouldn't your patch cause a regression compared to how it used
to work in earlier version of Xen?

Let me take a peek at the card in question and see if I can hook
up an extra RS232 connector.
> patch adding them to the list.
> 
> Jan
> 
> 
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