linux-kernel - Re: [PATCH] serial: 8250: Add support for using platform

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Message-ID: <87imunobk0.fsf@haabendal.dk>
Date:   Mon, 06 May 2019 17:19:27 +0200
From:   Esben Haabendal <esben@...bendal.dk>
To:     "Enrico Weigelt\, metux IT consult" <lkml@...ux.net>
Cc:     linux-serial@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Darwin Dingel <darwin.dingel@...iedtelesis.co.nz>,
        Jisheng Zhang <Jisheng.Zhang@...aptics.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        He Zhe <zhe.he@...driver.com>, Marek Vasut <marex@...x.de>,
        Douglas Anderson <dianders@...omium.org>,
        Paul Burton <paul.burton@...s.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] serial: 8250: Add support for using platform_device resources

"Enrico Weigelt, metux IT consult" <lkml@...ux.net> writes:

> On 30.04.19 16:04, Esben Haabendal wrote:
>> Allow getting memory resource (mapbase or iobase) as well as irq from
>> platform_device resources.
>> 
>> The UPF_DEV_RESOURCES flag must be set for devices where platform_device
>> resources are to be used.  When not set, driver behaves as before.
>> 
>> This allows use of the serial8250 driver together with devices with
>> resources added by platform_device_add_resources(), such as mfd child
>> devices added with mfd_add_devices().
>
> I like the idea (actually, quite the direction I'd like to go), but
> unfortunately it's more compilicated than that.
>
> Some drivers don't use these fields, eg. 8250 determines the mapsize
> based on several factors, at the time of the mapping is done. That's
> one of the things my patches shall clean up.

Could you take a quick look at my patch again.  The patch only changes
the probe method in the serial8250_isa_driver in 8250_core.c file.

So other drivers are not affected by this change.

And with the addition of the new UPF_DEV_RESOURCES flag, no existing
platforms should be affected either.

The patch merely makes it possible to start using plain "serial8250"
driver (serial8250_isa_driver) with standard platform resources, fx. as
implemented by mfd-core.

/Esben