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Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.5.1 MIME-Version: 1.0 In-Reply-To: <87ef7hai0e.fsf@codeaurora.org> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190308_010216_940640_C833448F X-CRM114-Status: GOOD ( 19.35 ) 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 On 08/03/2019 08:26, Kalle Valo wrote: > 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. I indeed plan to resend the series with a slightly different approach, removing support for the wake-up interrupt on mwifiex PCI devices altogether. Note that patch #3 is a fairly independent fix, which could be applied right now. Thanks, M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel