Hi, cc: Linus Walleij On Tue, Jun 11, 2019 at 10:00:41AM +0100, Marc Zyngier wrote: > On 11/06/2019 09:45, Geert Uytterhoeven wrote: > > CC irqchip > > > > Original thread at > > https://lore.kernel.org/lkml/20190607172958.20745-1-erosca@xxxxxxxxxxxxxx/ > > > > On Mon, Jun 10, 2019 at 10:30 AM Tony Lindgren <tony@xxxxxxxxxxx> wrote: > >> * Kalle Valo <kvalo@xxxxxxxxxxxxxx> [190610 07:01]: > >>> Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> writes: > >>> > >>>> The wl1837mod datasheet [1] says about the WL_IRQ pin: > >>>> > >>>> ---8<--- > >>>> SDIO available, interrupt out. Active high. [..] > >>>> Set to rising edge (active high) on powerup. > >>>> ---8<--- > >>>> > >>>> That's the reason of seeing the interrupt configured as: > >>>> - IRQ_TYPE_EDGE_RISING on HiKey 960/970 > >>>> - IRQ_TYPE_LEVEL_HIGH on a number of i.MX6 platforms > >>>> > >>>> We assert that all those platforms have the WL_IRQ pin connected > >>>> to the SoC _directly_ (confirmed on HiKey 970 [2]). > >>>> > >>>> That's not the case for R-Car Kingfisher extension target, which carries > >>>> a WL1837MODGIMOCT IC. There is an SN74LV1T04DBVR inverter present > >>>> between the WLAN_IRQ pin of the WL18* chip and the SoC, effectively > >>>> reversing the requirement quoted from [1]. IOW, in Kingfisher DTS > >>>> configuration we would need to use IRQ_TYPE_EDGE_FALLING or > >>>> IRQ_TYPE_LEVEL_LOW. > >>>> > >>>> Unfortunately, v4.2-rc1 commit bd763482c82ea2 ("wl18xx: wlan_irq: > >>>> support platform dependent interrupt types") made a special case out > >>>> of these interrupt types. After this commit, it is impossible to provide > >>>> an IRQ configuration via DTS which would describe an inverter present > >>>> between the WL18* chip and the SoC, generating the need for workarounds > >>>> like [3]. > >>>> > >>>> Create a boolean OF property, called "invert-irq" to specify that > >>>> the WLAN_IRQ pin of WL18* is connected to the SoC via an inverter. > >>>> > >>>> This solution has been successfully tested on R-Car H3ULCB-KF-M06 using > >>>> the DTS configuration [4] combined with the "invert-irq" property. > >>>> > >>>> [1] http://www.ti.com/lit/ds/symlink/wl1837mod.pdf > >>>> [2] https://www.96boards.org/documentation/consumer/hikey/hikey970/hardware-docs/ > >>>> [3] https://github.com/CogentEmbedded/meta-rcar/blob/289fbd4f8354/meta-rcar-gen3-adas/recipes-kernel/linux/linux-renesas/0024-wl18xx-do-not-invert-IRQ-on-WLxxxx-side.patch > >>>> [4] https://patchwork.kernel.org/patch/10895879/ > >>>> ("arm64: dts: ulcb-kf: Add support for TI WL1837") > >>>> > >>>> Signed-off-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> > >>> > >>> Tony&Eyal, do you agree with this? > >> > >> Yeah if there's some hardware between the WLAN device and the SoC > >> inverting the interrupt, I don't think we have clear a way to deal > >> with it short of setting up a separate irqchip that does the > >> translation. > > > > Yeah, inverting the interrupt type in DT works only for simple devices, > > that don't need configuration. > > A simple irqchip driver that just inverts the type sounds like a good > > solution to me. Does something like that already exists? > > We already have plenty of that in the tree, the canonical example > probably being drivers/irqchip/irq-mtk-sysirq.c. It should be pretty > easy to turn this driver into something more generic. I don't think drivers/irqchip/irq-mtk-sysirq.c can serve the use-case/purpose of this patch. The MTK driver seems to be dealing with the polarity inversion of on-SoC interrupts which are routed to GiC, whereas in this patch we are talking about an off-chip interrupt wired to R-Car GPIO controller. It looks to me that the nice DTS sketch shared by Linus Walleij in [5] might come closer to the concept proposed by Geert? FWIW, the infrastructure/implementation to make this possible is still not ready. One question to the wlcore/wl18xx maintainers: Why exactly do you give freedom to users to set the interrupt as LEVEL_LOW/EDGE_FALLING [6]? Apparently, this: - complicates the wl18xx driver, thus increasing the chance for bugs - is not supposed to reflect any HW differences between boards using LEVEL_LOW/EDGE_FALLING and the boards using LEVEL_HIGH/EDGE_RISING - doesn't bring any obvious advantage to the users, who are expected to sense the same behavior regardless of the IRQ type set in DTS - prevent the users to set IRQ type to LEVEL_LOW/EDGE_FALLING when there is an inverter present between WL_IRQ and SoC - seems to be not used almost at all, as 99% of mainline DTS set the IRQ type to the canonical/NLCP LEVEL_HIGH/EDGE_RISING [5] https://patchwork.ozlabs.org/patch/1095690/#2167076 ("[V1,1/2] gpio: make it possible to set active-state on GPIO lines") --------------------8<------------------- gpio0: gpio { compatible = "foo,chip"; gpio-controller; (...) }; inv0: inverter { compatible = "inverter"; gpio-controller; gpios = <&gpio0 0 GPIO_ACTIVE_HIGH>; }; consumer { compatible = "bar"; gpios = <&inv0 0 GPIO_ACTIVE_HIGH>; }; --------------------8<------------------- [6] bd763482c82ea2 ("wl18xx: wlan_irq: support platform dependent interrupt types") -- Best Regards, Eugeniu.
