linux-kernel - Re: [PATCH v4 1/5] PCI: Add pci_bus_fixup

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Message-ID: <20151007194426.GF27633@localhost>
Date:	Wed, 7 Oct 2015 14:44:26 -0500
From:	Bjorn Helgaas <helgaas@...nel.org>
To:	David Daney <ddaney.cavm@...il.com>
Cc:	linux-kernel@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
	linux-pci@...r.kernel.org, Will Deacon <will.deacon@....com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	Marc Zyngier <marc.zyngier@....com>,
	David Daney <david.daney@...ium.com>
Subject: Re: [PATCH v4 1/5] PCI: Add pci_bus_fixup_irqs().

Hi David,

On Fri, Oct 02, 2015 at 11:43:59AM -0700, David Daney wrote:
> From: David Daney <david.daney@...ium.com>
> 
> pci_bus_fixup_irqs() works like pci_fixup_irqs(), except it only does
> the fixups for devices on the specified bus.
> 
> Follow-on patch will use the new function.
> 
> Signed-off-by: David Daney <david.daney@...ium.com>
> ---
> No change from v2.
> 
>  drivers/pci/setup-irq.c | 30 ++++++++++++++++++++++++++++++
>  include/linux/pci.h     |  4 ++++
>  2 files changed, 34 insertions(+)
> 
> diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c
> index 95c225b..189ad17 100644
> --- a/drivers/pci/setup-irq.c
> +++ b/drivers/pci/setup-irq.c
> @@ -66,3 +66,33 @@ void pci_fixup_irqs(u8 (*swizzle)(struct pci_dev *, u8 *),
>  		pdev_fixup_irq(dev, swizzle, map_irq);
>  }
>  EXPORT_SYMBOL_GPL(pci_fixup_irqs);
> +
> +struct pci_bus_fixup_cb_info {
> +	u8 (*swizzle)(struct pci_dev *, u8 *);
> +	int (*map_irq)(const struct pci_dev *, u8, u8);
> +};
> +
> +static int pci_bus_fixup_irq_cb(struct pci_dev *dev, void *arg)
> +{
> +	struct pci_bus_fixup_cb_info *info = arg;
> +
> +	pdev_fixup_irq(dev, info->swizzle, info->map_irq);
> +	return 0;
> +}
> +
> +/*
> + * Fixup the irqs only for devices on the given bus using supplied
> + * swizzle and map_irq function pointers
> + */
> +void pci_bus_fixup_irqs(struct pci_bus *bus,
> +			u8 (*swizzle)(struct pci_dev *, u8 *),
> +			int (*map_irq)(const struct pci_dev *, u8, u8))
> +{
> +	struct pci_bus_fixup_cb_info info;
> +
> +	info.swizzle = swizzle;
> +	info.map_irq = map_irq;
> +	pci_walk_bus(bus, pci_bus_fixup_irq_cb, &info);

I don't like the existing pci_fixup_irqs(), so by transitivity, I
don't like pci_bus_fixup_irqs() either.  The problem is that in both
cases this is a one-time pass over the tree, so we don't handle
hot-added devices correctly.

I think we need to get rid of pci_fixup_irqs() and somehow integrate
it into the pci_device_add() path, where it would be done once for
every device we enumerate.  If we did that, I don't think you would
need to add pci_bus_fixup_irqs(), would you?

Bjorn

> +
> +}
> +EXPORT_SYMBOL_GPL(pci_bus_fixup_irqs);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index e90eb22..b505b50 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1120,6 +1120,10 @@ void pdev_enable_device(struct pci_dev *);
>  int pci_enable_resources(struct pci_dev *, int mask);
>  void pci_fixup_irqs(u8 (*)(struct pci_dev *, u8 *),
>  		    int (*)(const struct pci_dev *, u8, u8));
> +void pci_bus_fixup_irqs(struct pci_bus *,
> +			u8 (*)(struct pci_dev *, u8 *),
> +			int (*)(const struct pci_dev *, u8, u8));
> +
>  #define HAVE_PCI_REQ_REGIONS	2
>  int __must_check pci_request_regions(struct pci_dev *, const char *);
>  int __must_check pci_request_regions_exclusive(struct pci_dev *, const char *);
> -- 
> 1.9.1
> 
> --
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