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Fri, 8 Mar 2019 08:26:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1552033623; bh=GYvEHVZ8Hz0AsS4XKsMZAKT8P2zqxlUCAlYQX+OQjNY=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=EljLzFWpD8L94mi69QIE/YaL42fk0wnVnK82jrhHawCNWea7at/A0paZmsxzBjYod 7+9q63qDvquepsaDdbn1zXbDN+wNeeKwswvlfYQbM636MRxYAn0MMHATfLzhMlsDXz AmvQuiz7i17GEWIkIbgOYWodlHpb4AK+9dx+iuI8= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org DCA3D6030B Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=kvalo@codeaurora.org From: Kalle Valo To: Marc Zyngier Subject: Re: [PATCH 0/4] mwifiex PCI/wake-up interrupt fixes References: <20190224140426.3267-1-marc.zyngier@arm.com> Date: Fri, 08 Mar 2019 10:26:57 +0200 In-Reply-To: <20190224140426.3267-1-marc.zyngier@arm.com> (Marc Zyngier's message of "Sun, 24 Feb 2019 14:04:22 +0000") Message-ID: <87ef7hai0e.fsf@codeaurora.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190308_002705_146959_739B2FF7 X-CRM114-Status: GOOD ( 24.27 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ganapathi Bhat , Heiko Stuebner , devicetree@vger.kernel.org, Xinming Hu , netdev@vger.kernel.org, linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, Amitkumar Karwar , linux-rockchip@lists.infradead.org, Nishant Sarmukadam , Rob Herring , Enric Balletbo i Serra , "David S. Miller" , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Marc Zyngier 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel