linux-kernel - Re: PXA25x: GPIO driver fails probe due to resource conflict with pinctrl driver

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Message-ID: <Y5CxBzy47Gjn/V5a@lunn.ch>
Date:   Wed, 7 Dec 2022 16:28:07 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Jonathan Neuschäfer <j.neuschaefer@....net>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Daniel Mack <daniel@...que.org>, linux-kernel@...r.kernel.org
Subject: Re: PXA25x: GPIO driver fails probe due to resource conflict with
 pinctrl driver

On Wed, Dec 07, 2022 at 12:25:53PM +0100, Jonathan Neuschäfer wrote:
> Hello,
> 
> I am currently trying to bring up Linux 6.1-rcX on a PXA255 board, using a
> devicetree. One problem I encountered is that the PXA GPIO driver fails to
> probe because it uses the same MMIO register range as the pinctrl driver:
> 
> [    0.666169] pxa25x-pinctrl 40e00054.pinctrl: initialized pxa2xx pinctrl driver
> [    0.694407] pxa-gpio 40e00000.gpio: can't request region for resource [mem 0x40e00000-0x40e0ffff]
> [    0.695050] pxa-gpio: probe of 40e00000.gpio failed with error -16
> 
> Before I try to fix this myself: Is GPIO on PXA25x currently expected to
> work and when has it last been seen working?
> 
> What would be a good way to fix this?

How are the registers arranged? Is 0x40e00000-0x40e0ffff simply too
large, and making it smaller would fix the issue? Or are the registers
interleaved? It is possible to request a region in a non-exclusive
manor. Or is it more than interleaving, individual registers need to
be shared between the two drivers? If so, you have the locking issues
you mentioned.

    Andrew