Re: [PATCH 2/2] HISI LPC: Add ACPI UART support

[John Garry]

On 03/05/2018 17:56, Andy Shevchenko wrote:
> On Thu, 2018-05-03 at 23:08 +0800, John Garry wrote:
> > On the Huawei D03 development board the system UART is
> > the UART connected on the LPC bus.
> >
> > The profile for the device driver required for this HW
> > would be as follows:
> > - platform driver
> > - supports 16550
> > - supports ACPI
> > - supports polling mode
> > - supports IO space
> >
> > In principle we should use the PNP driver (8250_dw.c) for
> > 8250-devices with ACPI FW. However since this host driver
> > does not support PNP devices, and modifying the PNP core
> > code to support it is not worth the effort, use the generic
> > 8250 isa driver.
> >
> > For this, we need to setup the MFD cell platform data for
> > a serial 8250 Port.
> >
> > In addition to this change, we also make the following
> > changes:
> > - set child ACPI device as enumerated. This fixes a conflict
> >   in serdev setup for the UART
> > - use platform device ID auto for creating the uart child
> >   platform device to avoid conflict with platform devices
> >   created for serial8250_isa_devs from 8250_core.c

Hi Andy,

> > +	mfd_cell->platform_data = devm_kmemdup(hostdev, &ref_port,
> > +					       sizeof(ref_port),
> > GFP_KERNEL);
>
> Isn't this done by MFD core?

It does, but what we are copying from is on the stack and could be 
overwritten by the point we call the mfd_add_devices(). But this could 
be improved.

BTW, As seen in other discussion, future of MFD usage is in doubt, so 
all this may be dropped.

Thanks very much,
John

>