linux-kernel - Re: [PATCH v7 2/4] PCI: dwc: rockchip: add legacy interrupt support

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Message-ID: <87r15ta469.wl-maz@kernel.org>
Date:   Tue, 19 Apr 2022 09:05:50 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Peter Geis <pgwipeout@...il.com>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Heiko Stuebner <heiko@...ech.de>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        PCI <linux-pci@...r.kernel.org>,
        devicetree <devicetree@...r.kernel.org>,
        arm-mail-list <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v7 2/4] PCI: dwc: rockchip: add legacy interrupt support

On Tue, 19 Apr 2022 01:23:23 +0100,
Peter Geis <pgwipeout@...il.com> wrote:
> 
> > My only ask is that you properly initialise the HW. This will save
> > countless amount of head-scratching once you have a decent firmware or
> > kexec.
> 
> The only way to ensure that in a sane way is to trigger the resets at
> driver probe.

If that can be done, that'd be great.

> Can that be safely done without causing other issues with an already
> configured card or should I power cycle it as well?

Well, you are already renegotiating the link anyway, so that's a very
moot point.

> This is starting to feature creep from the original intention of this
> series, since a pre-configured controller would affect more than just
> interrupts.

Configuring the HW is not exactly a feature creep. If your intention
is to keep everything as it was left, then you don't have much of a
driver, but instead a time bomb. And we can do without another one in
the tree.

> If you wish, as a compromise I can ensure all INTx interrupts are
> masked at probe (which would hilariously be the opposite of
> downstream).

As far as I'm concerned, downstream doesn't exist. If someone wants
the downstream code, they can use it directly and we don't need to
merge this code.

If, on the other hand, you want this driver to be useful and to be
maintained upstream, initialising the interrupt mask is the absolute
bare minimum.

	M.

-- 
Without deviation from the norm, progress is not possible.