linux-kernel - Re: [PATCH 2/2] serial: 8250: Add support for 8250/16550 as MFD function

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Date:   Tue, 07 May 2019 14:04:34 +0200
From:   Esben Haabendal <esben@...bendal.dk>
To:     Lee Jones <lee.jones@...aro.org>
Cc:     linux-serial@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Nishanth Menon <nm@...com>,
        Vignesh R <vigneshr@...com>, Tony Lindgren <tony@...mide.com>,
        Lokesh Vutla <lokeshvutla@...com>,
        Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] serial: 8250: Add support for 8250/16550 as MFD function

Lee Jones <lee.jones@...aro.org> writes:

> On Fri, 26 Apr 2019, Esben Haabendal wrote:
>
>> The serial8250-mfd driver is for adding 8250/16550 UART ports as functions
>> to an MFD driver.
>> 
>> When calling mfd_add_device(), platform_data should be a pointer to a
>> struct plat_serial8250_port, with proper settings like .flags, .type,
>> .iotype, .regshift and .uartclk.  Memory (or ioport) and IRQ should be
>> passed as cell resources.
>
> What?  No, please!
>
> If you *must* create a whole driver just to be able to use
> platform_*() helpers (which I don't think you should), then please
> call it something else.  This doesn't have anything to do with MFD.

True.

I really don't think it is a good idea to create a whole driver just to
be able to use platform_get_*() helpers.  And if I am forced to do this,
because I am unable to convince Andy to improve the standard serial8250
driver to support that, it should be called MFD.  The driver would be
generally usable for all usecases where platform_get_*() works.

I don't have any idea what to call such a driver.  It really would just
be a fork of the current serial8250 driver, just allowing use of
platform_get_*(), supporting exactly the same hardware.

I am still hoping that we can find a way to improve serial8250 to be
usable in these cases.

/Esben