Re: [PATCH v2 0/3] HISI LPC ACPI UART support

From: Andy Shevchenko
Date: Tue May 08 2018 - 07:17:52 EST


On Tue, 2018-05-08 at 18:27 +0800, John Garry wrote:
> This patchset adds ACPI FW support for the UART on
> the LPC bus on the Huawei D03 development board.
>
> It also drops MFD API usage. It's not right to use MFD
> APIs outside drivers/mfd. As the alternate solution, we
> use platform device APIs directly.
>
> The UART is 8250-compatible, and has the following
> profile:
> - IO space iotype
> - no interrupt, so polling mode required
> - 16550 type
>
> Currently no platform driver exists for the UART. Indeed,
> for PNP-compatible devices - like this UART - it would be
> better to create a PNP device so that we may use the
> existing PNP driver. Thus, we should use the 8250 PNP
> driver.
>
> However this host driver does not support PNP devices.
> An RFC was sent for PNP support in [1]. However it was
> deemed impractical to follow this path.
>
> So to provide this UART support we use the 8250 generic
> isa driver. For this, we need to set the UART platform
> device name to match the 8250 isa driver. This means
> passing the 8250 serial config in the child pdev platform
> data.
>
> 1. https://lkml.org/lkml/2018/4/20/278
>

I'm fine with this least invasive approach. It seems it has minimum
duplication of code, which is anyway unavoidable when we are speaking of
instantiating platform devices.

FWIW,
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>

> Differences:
> v1 -> v2:
> - drop MFD API usage and use platform device APIs
> directly for ACPI support
>
> RFC -> v1:
> - drop PNP support
> - use static MFD cells
> - add 8250 setup
>
> John Garry (3):
> HISI LPC: Stop using MFD APIs
> HISI LPC: Re-Add ACPI child enumeration support
> HISI LPC: Add ACPI UART support
>
> drivers/bus/Kconfig | 1 -
> drivers/bus/hisi_lpc.c | 159 ++++++++++++++++++++++++++++++--------
> -----------
> 2 files changed, 97 insertions(+), 63 deletions(-)
>

--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy