linux-kernel - Re: [PATCH 00/04] PCI: rcar: Driver model and physical address space update

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Message-ID: <20140213043750.GA11908@verge.net.au>
Date:	Thu, 13 Feb 2014 13:37:50 +0900
From:	Simon Horman <horms@...ge.net.au>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
Cc:	Magnus Damm <magnus.damm@...il.com>, linux-pci@...r.kernel.org,
	linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org,
	valentine.barshak@...entembedded.com, ben.dooks@...ethink.co.uk
Subject: Re: [PATCH 00/04] PCI: rcar: Driver model and physical address space
 update

On Wed, Feb 12, 2014 at 01:59:11PM -0700, Bjorn Helgaas wrote:
> On Wed, Feb 05, 2014 at 03:52:43PM +0900, Magnus Damm wrote:
> > PCI: rcar: Driver model and physical address space update
> > 
> > [PATCH 01/04] PCI: rcar: Register each instance independently
> > [PATCH 02/04] PCI: rcar: Break out window size handling
> > [PATCH 03/04] PCI: rcar: Add DMABOUNCE support
> > [PATCH 04/04] PCI: rcar: Enable BOUNCE in case of HIGHMEM
> > 
> > These patches update the pci-rcar-gen2.c driver in various ways
> > including cleanups for driver model interface (1/4), readability
> > update (2/4) and also bounce buffer support (3/4, 4/4). Basically
> > the first two are just cleanups and the rest are fixes.
> > 
> > As it is today without these patches the system memory start address
> > is hard coded at 0x4000000 and the window is fixed at 1GiB. So we
> > have board specific code hidden in the driver which is good to avoid.
> > 
> > With these hard coded board specific constants there are some error cases
> > that are not handled, in particular the issue that only maximum 1GiB of
> > physical address space can be used for bus mastering with a single window.
> > The common case of using ARM CONFIG_VMSPLIT_3G results in no visible issues
> > as long as CONFIG_BOUNCE is used, but other CONFIG_VMSPLIT settings will
> > break due to the hard coded 1GiB window not being enough. It has been
> > verified that reducing the window size to 256MB makes the driver behave
> > the same with VMSPLIT_3G as 1GiB window size and other VMSPLIT settings.
> > 
> > To handle the maximum 1GiB physical address space limitation two types
> > of bounce buffers are added. The ARM specific DMABOUNCE code is in 3/4
> > hooked up to a chunk of local memory that is also handed of as coherent
> > memory to the pci devices hanging off the PCI bridge. The driver makes
> > sure to set the window so the local memory is always included. When the
> > PCI devices are operating and in case memory is used outside the window
> > then the DMABOUNCE buffers kicks in. This makes the driver support all
> > kinds of VMSPLIT settings and window sizes. The BOUNCE code in 4/4 is
> > selected to make sure bounce buffers are used for HIGHMEM.
> > 
> > With these patches this driver can be used with or without CMA and
> > with or without DMA zone. Basically the system wide memory setup is
> > left to the user. If a DMA zone is used then the PCI window will
> > be setup to cover that. Same thing with CMA.
> > 
> > Tested with USB storage using LPAE and various VMSPLIT settings together
> > with renesas git tag renesas-devel-v3.14-rc1-20140204 from kernel.org
> > 
> > Signed-off-by: Magnus Damm <damm@...nsource.se>
> > ---
> > 
> >  Written against renesas.git tag renesas-devel-v3.14-rc1-20140204
> > 
> >  drivers/pci/host/Kconfig         |    3 
> >  drivers/pci/host/pci-rcar-gen2.c |  367 +++++++++++++++++++++++++++++++-------
> >  2 files changed, 306 insertions(+), 64 deletions(-)
> 
> Simon, if you want to ack these, I'll be happy to merge them for v3.15.
> I'm not really qualified to review them myself.

Hi Bjorn,

Magnus has reposted these patches as part of a larger series
which includes some patches of his own. That series is
"[PATCH 00/08] PCI: rcar: Recent driver patches from Ben Dooks and me".
I am happy with it and will Ack it. Could you consider merging it?
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