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

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Message-ID: <20190521100904.GA13612@kroah.com>
Date:   Tue, 21 May 2019 12:09:04 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Esben Haabendal <esben@...bendal.dk>
Cc:     Lee Jones <lee.jones@...aro.org>, linux-serial@...r.kernel.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

On Tue, May 14, 2019 at 02:41:35PM +0200, Esben Haabendal wrote:
> Greg Kroah-Hartman <gregkh@...uxfoundation.org> writes:
> 
> > On Tue, May 14, 2019 at 11:47:41AM +0100, Lee Jones wrote:
> >> On Tue, 14 May 2019, Esben Haabendal wrote:
> >> 
> >> > Lee Jones <lee.jones@...aro.org> writes:
> >> > 
> >> > > On Tue, 07 May 2019, Esben Haabendal wrote:
> >> > >
> >> > >> 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
> >> > >
> >> > > I assume you mean "shouldn't"?
> >> > 
> >> > Of-course.
> >> > 
> >> > >> 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.
> >> > >
> >> > > Me too.
> >> > 
> >> > Unfortunately, I don't seem to be able to convince Andy to accept
> >> > something like that.
> >> 
> >> Andy is not he Maintainer.
> >> 
> >> What are Greg and Jiri's opinions?
> >
> > I've been ignoring all of this at the moment because of the 5.2-rc merge
> > window.  I'll look at it after -rc1 is out.
> >
> > thanks,
> > greg k-h
> 
> Great, thanks!
> 
> I will try ad hold back with this thread until you get back to it.

Ok, I have no idea what is going on here, sorry.  This is a really long
and meandering thread, and I can't even find the original patches in my
queue.

So can you resend things and we can start over?  :)

But note, using a mfd for a uart seems VERY odd to me...

thanks,

greg k-h