linux-kernel - Re: [PATCH v9 5/7] ACPI: Translate the I/O range of non-MMIO devices before scanning

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Date:   Tue, 6 Jun 2017 09:55:53 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Gabriele Paoloni <gabriele.paoloni@...wei.com>, rafael@...nel.org
Cc:     "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "frowand.list@...il.com" <frowand.list@...il.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "brian.starkey@....com" <brian.starkey@....com>,
        "olof@...om.net" <olof@...om.net>,
        "benh@...nel.crashing.org" <benh@...nel.crashing.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
        Linuxarm <linuxarm@...wei.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "minyard@....org" <minyard@....org>,
        John Garry <john.garry@...wei.com>,
        "xuwei (O)" <xuwei5@...ilicon.com>
Subject: Re: [PATCH v9 5/7] ACPI: Translate the I/O range of non-MMIO devices
 before scanning

Hi Gab, Rafael,

On Wed, May 31, 2017 at 10:24:47AM +0000, Gabriele Paoloni wrote:

[...]

> > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> > > index e39ec7b..37dd23c 100644
> > > --- a/drivers/acpi/scan.c
> > > +++ b/drivers/acpi/scan.c
> > > @@ -2035,6 +2035,7 @@ int __init acpi_scan_init(void)
> > >  	acpi_int340x_thermal_init();
> > >  	acpi_amba_init();
> > >  	acpi_watchdog_init();
> > > +	acpi_indirectio_scan_init();

Unfortunately this is becoming a pattern and we are ending up
with a static ordering of "subsystems" init (even though for this
LPC series it is just the Hisilicon driver that requires this call)
and I am not sure I see any way of avoiding it. I think that's always
been the case in x86, with fewer subsystems/kernel paths to care
about, I wanted to flag this up though to check your opinion since
I am not sure this is the right direction we are taking.

I also think that relying on _DEP to build any dependency is not
entirely a) usable (owing to legacy bindings and previous _DEP misuse)
and b) compliant with ACPI bindings given that _DEP has to be used
for operation regions only.

Thoughts ?

Thanks,
Lorenzo

> > >  	acpi_scan_add_handler(&generic_device_handler);
> > >
> > > diff --git a/include/acpi/acpi_indirect_pio.h
> > b/include/acpi/acpi_indirect_pio.h
> > > new file mode 100644
> > > index 0000000..efc5c43
> > > --- /dev/null
> > > +++ b/include/acpi/acpi_indirect_pio.h
> > > @@ -0,0 +1,24 @@
> > > +/*
> > > + * ACPI support for indirect-PIO bus.
> > > + *
> > > + * Copyright (C) 2017 Hisilicon Limited, All Rights Reserved.
> > > + * Author: Gabriele Paoloni <gabriele.paoloni@...wei.com>
> > > + * Author: Zhichang Yuan <yuanzhichang@...ilicon.com>
> > > + *
> > > + * This program is free software; you can redistribute it and/or
> > modify
> > > + * it under the terms of the GNU General Public License version 2 as
> > > + * published by the Free Software Foundation.
> > > + */
> > > +
> > > +#ifndef _ACPI_INDIRECT_PIO_H
> > > +#define _ACPI_INDIRECT_PIO_H
> > > +
> > > +struct indirect_pio_device_desc {
> > > +	void *pdata; /* device relevant info data */
> > > +	int (*pre_setup)(struct acpi_device *adev, void *pdata);
> > > +};
> > > +
> > > +int acpi_set_logic_pio_resource(struct device *child,
> > > +		struct device *hostdev);
> > > +
> > > +#endif
> > > --
> > > 2.7.4
> > >
> > >