From: Andrew Murray <andrew.murray@arm.com>
To: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Florian Fainelli <f.fainelli@gmail.com>,
mbrugger@suse.com, maz@kernel.org, phil@raspberrypi.org,
linux-kernel@vger.kernel.org, jeremy.linton@arm.com,
Eric Anholt <eric@anholt.net>,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
bcm-kernel-feedback-list@broadcom.com,
Stefan Wahren <wahrenst@gmx.net>,
james.quinlan@broadcom.com, linux-pci@vger.kernel.org,
Bjorn Helgaas <bhelgaas@google.com>,
linux-arm-kernel@lists.infradead.org,
linux-rpi-kernel@lists.infradead.org
Subject: Re: [PATCH v2 4/6] PCI: brcmstb: add Broadcom STB PCIe host controller driver
Date: Thu, 21 Nov 2019 15:46:55 +0000 [thread overview]
Message-ID: <20191121154655.GB43905@e119886-lin.cambridge.arm.com> (raw)
In-Reply-To: <18109ee4f8d8c5ce0dc714217eef53ee42d5305f.camel@suse.de>
On Thu, Nov 21, 2019 at 02:26:15PM +0100, Nicolas Saenz Julienne wrote:
> On Thu, 2019-11-21 at 12:03 +0000, Andrew Murray wrote:
> > On Wed, Nov 20, 2019 at 08:53:30PM +0100, Nicolas Saenz Julienne wrote:
> > One purpose of this function is to validate that the information given in the
> > device tree is valid - I've seen other feedback on these lists where the view
> > is taken that 'it's not the job of the kernel to validate the DT'. Subscribing
> > to this view would be a justification for removing this validation -
> > especially
> > given that the bindings you include have only one dma-range (in any case if
> > there are constraints you ought to include them in the binding document).
> >
> > Though the problem with this point of view is that if the DT is wrong, it may
> > be possible for the driver to work well enough to do some function but with
> > some horrible side effects that are difficult to track down to a bad DT.
>
> As for the validation, I think in this specific case it's still worthwhile. As
> you might know, there is a bug on the first revision of RPI4's PCIe integration
> which blocks any access higher than 3GB. Further revisions fix this and allow
> full memory addressing.
>
> I've been working with Phil Elwell (from the RPi foundation) to solve this in a
> way that plays well with upstream and this driver (I'll be able to test the new
> revision before this gets in). The solution is, unsurprisingly, for the
> firmware to edit the DTB passed to the kernel based on the board revision.
> Given that there is some live manipulation of the dma-ranges I'd rather leave
> the validation check.
>
> If you don't disagree with the above I'll add an extra code comment explaining
> why we feel the need to verify the device-tree contents.
I'll be interested in seeing it.
Thanks,
Andrew Murray
>
> Regards,
> Nicolas
>
next prev parent reply other threads:[~2019-11-21 15:46 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-12 15:59 [PATCH v2 0/6] Raspberry Pi 4 PCIe support Nicolas Saenz Julienne
2019-11-12 15:59 ` [PATCH v2 1/6] linux/log2.h: Add roundup/rounddown_pow_two64() family of functions Nicolas Saenz Julienne
2019-11-19 11:13 ` Andrew Murray
2019-11-19 11:30 ` Nicolas Saenz Julienne
2019-11-19 12:43 ` Nicolas Saenz Julienne
2019-11-19 16:28 ` Andrew Murray
2019-11-19 16:55 ` Jason Gunthorpe
2019-11-19 17:00 ` Andrew Murray
2019-11-12 15:59 ` [PATCH v2 2/6] dt-bindings: PCI: Add bindings for brcmstb's PCIe device Nicolas Saenz Julienne
2019-11-18 21:23 ` Rob Herring
2019-11-19 9:35 ` Nicolas Saenz Julienne
2019-11-19 11:17 ` Andrew Murray
2019-11-19 11:28 ` Nicolas Saenz Julienne
2019-11-12 15:59 ` [PATCH v2 3/6] ARM: dts: bcm2711: Enable PCIe controller Nicolas Saenz Julienne
2019-11-12 15:59 ` [PATCH v2 4/6] PCI: brcmstb: add Broadcom STB PCIe host controller driver Nicolas Saenz Julienne
2019-11-19 16:25 ` Andrew Murray
2019-11-19 18:20 ` Jeremy Linton
2019-11-20 20:24 ` Nicolas Saenz Julienne
2019-11-19 18:34 ` Florian Fainelli
2019-11-21 12:16 ` Andrew Murray
2019-11-20 19:53 ` Nicolas Saenz Julienne
2019-11-21 12:03 ` Andrew Murray
2019-11-21 12:59 ` Nicolas Saenz Julienne
2019-11-21 15:44 ` Andrew Murray
2019-11-21 21:07 ` Jim Quinlan
2019-11-22 14:59 ` Robin Murphy
2019-11-21 13:26 ` Nicolas Saenz Julienne
2019-11-21 15:46 ` Andrew Murray [this message]
2019-11-12 15:59 ` [PATCH v2 5/6] PCI: brcmstb: add MSI capability Nicolas Saenz Julienne
2019-11-13 13:49 ` Marc Zyngier
2019-11-21 15:38 ` Andrew Murray
2019-11-21 17:19 ` Nicolas Saenz Julienne
2019-11-12 15:59 ` [PATCH v2 6/6] MAINTAINERS: Add brcmstb PCIe controller Nicolas Saenz Julienne
2019-11-19 11:18 ` [PATCH v2 0/6] Raspberry Pi 4 PCIe support Andrew Murray
2019-11-19 11:49 ` Nicolas Saenz Julienne
2019-11-21 12:18 ` Andrew Murray
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