Re: [RFC PATCH 0/2] serial: 8250_dw: IO space + polling mode support

[John Garry]

On 26/02/2018 12:21, Andy Shevchenko wrote:
> On Mon, 2018-02-26 at 11:56 +0000, John Garry wrote:
> > > > > > > Why you can't do properly in ACPI?
> > > > >
> > > > > No answer here either.
> > > > >
> > > > > Sorry, but with this level of communication it's no go for the
> > > > > series.
> > > >
> > > > Sorry if my answers did not tell you want you want to know.
> > > >
> > > > My point was that the 8250_pnp driver would be used for a
> > > > pnp_device,
> > > > but we are creating a platform device for this UART slave so would
> > > > require a platform device driver, that which 8250_dw.c is. But I
> > > > will
> > > > check on pnp device support.
> >
> > Hi Andy,
> >
> > > Perhaps it's not visible, though below is a description of the
> > > drivers
> > > we have:
> > >
> > > 8250_dw - OF/ACPI driver for Synopsys DW (+ DW DMA)
> > > 8250_lpss - PCI driver for Synopsys DW (+ DW DMA)
> > > 8250_of -  generic 8250 compatible driver for OF
> > > 8250_pci - generic 8250 compatible driver for PCI
> > > 8250_pnp - generic 8250 compatible driver for ACPI
> > >
> > > 8250_* (except core parts) - custom glue drivers per some IPs
> > >
> > > By description you gave your driver fits 8250_pnp if ACPI tables
> > > crafted
> > > properly.
> > >
> > > Share the ACPI excerpt and we can discuss further how to improve
> > > them.

Hi Andy,

> > For a bit of background, MFD support was discussed here initially:
> > https://lkml.org/lkml/2017/6/13/796
> >
> > Here is the ACPI table:
> > Scope(_SB) {
> >    Device (LPC0) {
> >      Name (_HID, "HISI0191")  // HiSi LPC
> >      Name (_CRS, ResourceTemplate () {
> >        Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
> >      })
> >    }
> >
> >    Device (LPC0.CON0) {
> >      Name (_HID, "HISI1031")
> >      // Name (_CID, "PNP0501") // cannot support PNP
> >      Name (LORS, ResourceTemplate() {
> >        QWordIO (
> >          ResourceConsumer,
> >      MinNotFixed,     // _MIF
> >      MaxNotFixed,     // _MAF
> >      PosDecode,
> >      EntireRange,
> >      0x0,             // _GRA
> >      0x2F8,           // _MIN
>
> >      0x3fff,          // _MAX
>
> Shouldn't be 0x2ff ?

Yes, something like this. I have asked for it to be fixed.

> >      0x0,             // _TRA
> >      0x08,            // _LEN
> >      , ,
> >      IO02
> >
> >
> > The latest framework changes and host driver patchset are here:
> > https://lkml.org/lkml/2018/2/19/465
>
> It still doesn't explain impediments you have.
>
> Just few approaches comes to my mind:
>  - move UART outside of parent device

In this case the UART would not be a child and would not be enumerated 
to have the correct iobase.

>  - register PNP driver manually for that cell instead of MFD

Maybe it could work.

>  - use serial8250 platform driver (I totally forgot that we have a
> generic platform driver, so, it might be what you need to use at the
> end)

Let me check this also. I am not fimilar.

>

Thanks for the support!
John