From: Kalle Valo <kvalo@codeaurora.org>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Amitkumar Karwar <amitkarwar@gmail.com>,
Enric Balletbo i Serra <enric.balletbo@collabora.com>,
Ganapathi Bhat <gbhat@marvell.com>,
Heiko Stuebner <heiko@sntech.de>,
Nishant Sarmukadam <nishants@marvell.com>,
Rob Herring <robh+dt@kernel.org>,
Xinming Hu <huxinming820@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org,
linux-wireless@vger.kernel.org, netdev@vger.kernel.org
Subject: Re: [PATCH 0/4] mwifiex PCI/wake-up interrupt fixes
Date: Fri, 08 Mar 2019 10:26:57 +0200 [thread overview]
Message-ID: <87ef7hai0e.fsf@codeaurora.org> (raw)
In-Reply-To: <20190224140426.3267-1-marc.zyngier@arm.com> (Marc Zyngier's message of "Sun, 24 Feb 2019 14:04:22 +0000")
Marc Zyngier <marc.zyngier@arm.com> writes:
> For quite some time, I wondered why the PCI mwifiex device built in my
> Chromebook was unable to use the good old legacy interrupts. But as MSIs
> were working fine, I never really bothered investigating. I finally had a
> look, and the result isn't very pretty.
>
> On this machine (rk3399-based kevin), the wake-up interrupt is described as
> such:
>
> &pci_rootport {
> mvl_wifi: wifi@0,0 {
> compatible = "pci1b4b,2b42";
> reg = <0x83010000 0x0 0x00000000 0x0 0x00100000
> 0x83010000 0x0 0x00100000 0x0 0x00100000>;
> interrupt-parent = <&gpio0>;
> interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
> pinctrl-names = "default";
> pinctrl-0 = <&wlan_host_wake_l>;
> wakeup-source;
> };
> };
>
> Note how the interrupt is part of the properties directly attached to the
> PCI node. And yet, this interrupt has nothing to do with a PCI legacy
> interrupt, as it is attached to the wake-up widget that bypasses the PCIe RC
> altogether (Yay for the broken design!). This is in total violation of the
> IEEE Std 1275-1994 spec[1], which clearly documents that such interrupt
> specifiers describe the PCI device interrupts, and must obey the
> INT-{A,B,C,D} mapping. Oops!
>
> The net effect of the above is that Linux tries to do something vaguely
> sensible, and uses the same interrupt for both the wake-up widget and the
> PCI device. This doesn't work for two reasons: (1) the wake-up widget grabs
> the interrupt in exclusive mode, and (2) the PCI interrupt is still routed
> to the RC, leading to a screaming interrupt. This simply cannot work.
>
> To sort out this mess, we need to lift the confusion between the two
> interrupts. This is done by extending the DT binding to allow the wake-up
> interrupt to be described in a 'wake-up' subnode, sidestepping the issue
> completely. On my Chromebook, it now looks like this:
>
> &pci_rootport {
> mvl_wifi: wifi@0,0 {
> compatible = "pci1b4b,2b42";
> reg = <0x83010000 0x0 0x00000000 0x0 0x00100000
> 0x83010000 0x0 0x00100000 0x0 0x00100000>;
> pinctrl-names = "default";
> pinctrl-0 = <&wlan_host_wake_l>;
> wake-up {
> interrupt-parent = <&gpio0>;
> interrupts = <8 IRQ_TYPE_LEVEL_LOW>;
> wakeup-source;
> };
> };
> };
>
> The driver is then updated to look for this subnode first, and fallback to
> the original, broken behaviour (spitting out a warning in the offending
> configuration).
>
> For good measure, there are two additional patches:
>
> - The wake-up interrupt requesting is horribly racy, and could lead to
> unpredictable behaviours. Let's fix that properly.
>
> - A final patch implementing the above transformation for the whole
> RK3399-based Chromebook range, which all use the same broken
> configuration.
>
> With all that, I finally have PCI legacy interrupts working with the mwifiex
> driver on my Chromebook.
>
> [1] http://www.devicetree.org/open-firmware/bindings/pci/pci2_1.pdf
>
> Marc Zyngier (4):
> dt-bindings/marvell-8xxx: Allow wake-up interrupt to be placed in a
> separate node
> mwifiex: Fetch wake-up interrupt from 'wake-up' subnode when it exists
> mwifiex: Flag wake-up interrupt as IRQ_NOAUTOEN rather than disabling
> it too late
> arm64: dts: rockchip: gru: Move wifi wake-up interrupt into its own
> subnode
>
> .../bindings/net/wireless/marvell-8xxx.txt | 23 ++++++++++++++++++-
> .../dts/rockchip/rk3399-gru-chromebook.dtsi | 8 ++++---
> drivers/net/wireless/marvell/mwifiex/main.c | 13 +++++++++--
> 3 files changed, 38 insertions(+), 6 deletions(-)
I didn't read the discussion in detail, but I understanding is that I
should drop this series and wait for a new version. Please correct me if
I misunderstood.
--
Kalle Valo
next prev parent reply other threads:[~2019-03-08 8:27 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-24 14:04 [PATCH 0/4] mwifiex PCI/wake-up interrupt fixes Marc Zyngier
2019-02-24 14:04 ` [PATCH 1/4] dt-bindings/marvell-8xxx: Allow wake-up interrupt to be placed in a separate node Marc Zyngier
2019-02-24 14:04 ` [PATCH 2/4] mwifiex: Fetch wake-up interrupt from 'wake-up' subnode when it exists Marc Zyngier
2019-02-24 14:04 ` [PATCH 3/4] mwifiex: Flag wake-up interrupt as IRQ_NOAUTOEN rather than disabling it too late Marc Zyngier
2019-02-26 23:31 ` Brian Norris
2019-02-26 23:34 ` Brian Norris
2019-04-04 10:22 ` Kalle Valo
2019-02-24 14:04 ` [PATCH 4/4] arm64: dts: rockchip: gru: Move wifi wake-up interrupt into its own subnode Marc Zyngier
2019-02-25 12:45 ` [PATCH 0/4] mwifiex PCI/wake-up interrupt fixes Ard Biesheuvel
2019-02-25 14:52 ` Marc Zyngier
2019-02-26 16:21 ` Ard Biesheuvel
2019-02-26 17:14 ` Marc Zyngier
2019-02-26 23:44 ` Brian Norris
2019-02-27 9:27 ` Marc Zyngier
2019-02-26 23:28 ` Brian Norris
2019-02-27 10:02 ` Marc Zyngier
2019-02-27 10:16 ` Ard Biesheuvel
2019-02-27 20:57 ` Brian Norris
2019-02-27 23:03 ` Rafael J. Wysocki
2019-02-28 2:29 ` Brian Norris
2019-02-28 11:03 ` Rafael J. Wysocki
2019-02-27 20:51 ` Brian Norris
2019-03-08 8:26 ` Kalle Valo [this message]
2019-03-08 9:02 ` Marc Zyngier
2019-03-08 9:36 ` Kalle Valo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87ef7hai0e.fsf@codeaurora.org \
--to=kvalo@codeaurora.org \
--cc=amitkarwar@gmail.com \
--cc=davem@davemloft.net \
--cc=devicetree@vger.kernel.org \
--cc=enric.balletbo@collabora.com \
--cc=gbhat@marvell.com \
--cc=heiko@sntech.de \
--cc=huxinming820@gmail.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-rockchip@lists.infradead.org \
--cc=linux-wireless@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=netdev@vger.kernel.org \
--cc=nishants@marvell.com \
--cc=robh+dt@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).