Linux-PCI Archive on lore.kernel.org
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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	linux-pci <linux-pci@vger.kernel.org>,
	Sinan Kaya <okaya@kernel.org>,
	linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>
Subject: Re: [RFC PATCH v2] arm64: acpi/pci: invoke _DSM whether to preserve firmware PCI setup
Date: Fri, 14 Jun 2019 23:48:18 +1000
Message-ID: <fdedfe23250f0dcb49619ed9da1d53ff7e7403d8.camel@kernel.crashing.org> (raw)
In-Reply-To: <20190614131253.GR13533@google.com>

On Fri, 2019-06-14 at 08:12 -0500, Bjorn Helgaas wrote:
> On Fri, Jun 14, 2019 at 08:43:19PM +1000, Benjamin Herrenschmidt
> wrote:
> 
> > This least to another conversation we hinted at earlier.. we should
> > probably have a way to do the same at least for BARs on ACPI
> > systems so
> > we don't have to temporarily disable access to a device to size
> > them.
> 
> The PCI Enhanced Allocation capability provides a way to do this.  I
> don't know how widely used it is, but it's theoretically possible.

Ok, I have to read about this. I haven't seen a device with that on
yet, it looks messy at a quick glance.

Can ACPI convey the information ? On powerpc and sparc64 we have ways
to read the BAR values from the device-tree created by OF when it
assigned them.

Cheers,
Ben.



  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-13  7:54 Benjamin Herrenschmidt
2019-06-13 19:02 ` Bjorn Helgaas
2019-06-13 21:59   ` Benjamin Herrenschmidt
2019-06-13 23:07   ` Benjamin Herrenschmidt
2019-06-14  7:42     ` Ard Biesheuvel
2019-06-14  8:36       ` Benjamin Herrenschmidt
2019-06-14  9:57         ` Lorenzo Pieralisi
2019-06-14 10:36           ` Benjamin Herrenschmidt
2019-06-14 10:43             ` Benjamin Herrenschmidt
2019-06-14 13:12               ` Bjorn Helgaas
2019-06-14 13:48                 ` Benjamin Herrenschmidt [this message]
2019-06-14 20:13                   ` Bjorn Helgaas
2019-06-15  1:18                     ` Benjamin Herrenschmidt
2019-06-14 13:09         ` Bjorn Helgaas
2019-06-14 13:46           ` Benjamin Herrenschmidt

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