On Fri, Sep 25, 2015 at 12:05:10AM -0700, Gregory Fong wrote:
> Hi all,
>
> On Thu, Sep 17, 2015 at 1:15 AM, Heikki Krogerus
> <heikki.krogerus@xxxxxxxxxxxxxxx> wrote:
> > On Thu, Sep 17, 2015 at 12:50:40PM +0800, Ken Xue wrote:
> >> On Wed, 2015-09-16 at 14:30 +0300, Heikki Krogerus wrote:
> >> > On Tue, Sep 15, 2015 at 04:29:45PM +0300, Andy Shevchenko wrote:
> >> > > > + id = acpi_match_device(p->dev->driver
> >> > > > ->acpi_match_table, p->dev);
> >> > > > + if ((id && strcmp(id->id, "AMD0020") &&
> >> > > > + strcmp(id->id, "APMC0D08")) || !id) {
> >> > >
> >> > > Shouldn't we ask the actual owners of such devices if they have the
> >> > > Busy Functionality enabled?
> >> >
> >> > Yes. Now this check will simply ensure that the behaviour on those
> >> > platforms is the same as before. But in any case, like you said, let's
> >> > get the confirmation.
> >> >
> >> > Ken, Feng! Could you tell us if the DW_apb_uart on your platforms has
> >> > the Busy Functionality or not (UART_16550_COMPATIBLE)?
> >>
> >> Thanks for your reminders.
> >> Currently, "AMD0020" also does not support "UART_IIR_BUSY".
> >
> > Cool! Then we can just drop that condition completely and just set the
> > uart_16550_compatible flag always if ACPI companion exists.
> >
>
> Hijacking this thread since this reminded me of a question that I had
> a while back but never followed up on: is there any particular reason
> to prefer the 8250_dw instead of the regular 8250 driver when
> UART_16550_COMPATIBLE is set? Wouldn't the regular 8250 driver then
> work fine, since the block is then supposed to behave like a NatSemi
> 16550?
UART_16550_COMPATIBLE only means the UART doesn't have busy
functionality, which is one feature out of many. For example, we still
want to use the DW_apb_uart specific UART Component Parameter register
to get the fifo size and knowing do we set UART_CAP_AFE, etc. exactly
the same way, regardless are we UART_16550_COMPATIBLE or not.
Thanks,
--
heikki
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