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

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Date:   Wed, 7 Dec 2022 17:40:29 +0100
From:   Jonathan Neuschäfer <j.neuschaefer@....net>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     Jonathan Neuschäfer <j.neuschaefer@....net>,
        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 04:28:07PM +0100, Andrew Lunn wrote:
> 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

(I wrote this before I saw the other reply, so there are probably
 duplicate information)

They overlap. pxa25x.dtsi declares:

	pinctrl: pinctrl@...00000 {
		reg = <0x40e00054 0x20>,  // base_af[0]
		      <0x40e0000c 0xc>,   // base_dir[0]
		      <0x40e0010c 4>,     // base_dir[3]
		      <0x40f00020 0x10>;  // base_sleep[0]
		compatible = "marvell,pxa25x-pinctrl";
	};

(comments mine, based on pinctrl-pxxa25x.c)


The GPIO driver mentions these registers (for PXA25x):

	          GPLR    GPDR    GPSR    GPCR    GRER    GFER    GEDR
	BANK 0 - 0x0000  0x000C  0x0018  0x0024  0x0030  0x003C  0x0048
	BANK 1 - 0x0004  0x0010  0x001C  0x0028  0x0034  0x0040  0x004C
	BANK 2 - 0x0008  0x0014  0x0020  0x002C  0x0038  0x0044  0x0050

So, there are overlaps in GPDR (0x0c-0x14, GPIO pin direction register).

The register at 0x10c seems bogus for PXA25x: gpio-pxa.c mentions it as
part of bank 3, which only exists in PXA27x or later.


Jonathan

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