Re: [PATCH 0/2] PCI: fix pci-mvebu after conversion to common bridge emul code

From: Bjorn Helgaas <helgaas@kernel.org>
To: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: "Lorenzo Pieralisi" <lorenzo.pieralisi@arm.com>,
	linux-pci@vger.kernel.org, "Andrew Lunn" <andrew@lunn.ch>,
	"Russell King" <linux@arm.linux.org.uk>,
	"Jason Cooper" <jason@lakedaemon.net>,
	"Gregory Clement" <gregory.clement@bootlin.com>,
	"Leigh Brown" <leigh@solinno.co.uk>,
	"Luís Mendes" <luis.p.mendes@gmail.com>,
	linux-arm-kernel@lists.infradead.org,
	"Sebastian Hesselbarth" <sebastian.hesselbarth@gmail.com>
Subject: Re: [PATCH 0/2] PCI: fix pci-mvebu after conversion to common bridge emul code
Date: Thu, 21 Feb 2019 17:23:17 -0600	[thread overview]
Message-ID: <20190221232317.GB219879@google.com> (raw)
In-Reply-To: <20190220094841.11129-1-thomas.petazzoni@bootlin.com>

On Wed, Feb 20, 2019 at 10:48:39AM +0100, Thomas Petazzoni wrote:
> Hello,
> 
> This set of two patches aim at fixing some regression reported by two
> users (Luis and Leigh), that were introduced by the conversion of the
> pci-mvebu driver to the common PCI bridge emulation code shared
> between pci-aardvark and pci-mvebu.
> 
> Due to this conversion, some registers of the PCI configuration that
> used to be read-only are now read-write, making the Linux PCI core
> believe that some features are implemented by the PCI bridge. Namely
> in the case of pci-mvebu, the prefetchable memory base/limit registers
> were read-only, while they are now read-write. Due to this, the Linux
> PCI core now believes it can configure a prefetchable memory area, but
> this is not supported by pci-mvebu, which does not have the logic to
> create the appropriate MBUs windows.
> 
> This set of two commits allow PCI controller code to tell the PCI
> bridge emulation logic about their capabilities. Because we envision
> that other capabilities than prefetchable memory support might need to
> be communicated from the PCI controller code to the PCI bridge
> emulation code in the future, we introduce a "flags" argument, even if
> for now only one flag is supported.
> 
> Lorenzo, let me know what you think about this approach. I am open to
> suggestions if the proposed approach is not satisfying.
> 
> Both patches have been confirmed by Luis and Leigh to fix the
> regression, but I'll let them give a formal Tested-by.
> 
> Best regards,
> 
> Thomas Petazzoni
> 
> Thomas Petazzoni (2):
>   PCI: pci-bridge-emul: Create per-bridge copy of register behavior
>   PCI: pci-bridge-emul: Extend pci_bridge_emul_init() with flags
> 
>  drivers/pci/controller/pci-aardvark.c |  2 +-
>  drivers/pci/controller/pci-mvebu.c    |  2 +-
>  drivers/pci/pci-bridge-emul.c         | 86 ++++++++++++++++++---------
>  drivers/pci/pci-bridge-emul.h         | 13 +++-
>  4 files changed, 73 insertions(+), 30 deletions(-)

Lorenzo, I assume you'll take both of these, so for both patches,

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

Maybe we should add a stable tag (v4.20+)?