From: Samuel Holland <samuel@sholland.org> To: Marc Zyngier <maz@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de>, Rob Herring <robh+dt@kernel.org>, Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>, Jernej Skrabec <jernej.skrabec@siol.net>, Ondrej Jirman <megous@megous.com>, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 03/10] irqchip/sun6i-r: Use a stacked irqchip driver Date: Thu, 14 Jan 2021 22:01:59 -0600 [thread overview] Message-ID: <495f71d0-9dbf-23d2-45a1-f27b15138bb2@sholland.org> (raw) In-Reply-To: <87turjjkjr.wl-maz@kernel.org> Hello, On 1/14/21 3:06 PM, Marc Zyngier wrote: > Hi Samuel, > > On 2021-01-12 05:59, Samuel Holland wrote: > > [...] > >> +static void sun6i_r_intc_ack_nmi(void) >> +{ >> + writel(SUN6I_NMI_BIT, base + SUN6I_IRQ_PENDING(0)); > > writel_relaxed() irq_chip_unmask_parent(), which calls gic_unmask_irq(), is called immediately after this in .irq_unmask. Since gic_unmask_irq() also uses writel_relaxed(), the GIC write could be ordered before the write here. I was getting occasional spurious interrupts (1 out of each 20-25) when using a level trigger, which were resolved by switching to writel() here. I mentioned this in the changelog, but it probably deserves a comment in the code as well. Or maybe I should use an explicit barrier somewhere? >> +} >> + >> +static void sun6i_r_intc_nmi_ack(struct irq_data *data) >> +{ >> + if (irqd_get_trigger_type(data) & IRQ_TYPE_EDGE_BOTH) >> + sun6i_r_intc_ack_nmi(); >> + else >> + data->chip_data = SUN6I_NMI_NEEDS_ACK; >> +} >> + >> +static void sun6i_r_intc_nmi_eoi(struct irq_data *data) >> +{ >> + /* For oneshot IRQs, delay the ack until the IRQ is unmasked. */ >> + if (data->chip_data == SUN6I_NMI_NEEDS_ACK && !irqd_irq_masked(data)) >> { >> + sun6i_r_intc_ack_nmi(); >> + data->chip_data = 0; > > nit: NULL rather than 0? NULL seemed less appropriate since I'm not using the field as a pointer, but I don't have a strong opinion about it. > [...] > >> +static struct irq_chip sun6i_r_intc_nmi_chip = { >> + .name = "sun6i-r-intc", >> + .irq_ack = sun6i_r_intc_nmi_ack, >> + .irq_mask = irq_chip_mask_parent, >> + .irq_unmask = sun6i_r_intc_nmi_unmask, >> + .irq_eoi = sun6i_r_intc_nmi_eoi, >> + .irq_set_affinity = irq_chip_set_affinity_parent, >> + .irq_set_type = sun6i_r_intc_nmi_set_type, >> + .irq_set_irqchip_state = sun6i_r_intc_nmi_set_irqchip_state, > > You probably also want to wire irq_get_irqchip_state(), while > you're at it. I thought if the interrupt was pending here, it would necessarily also be pending at the GIC, so adding a separate layer would be redundant. irq_set_vcpu_affinity(), __irq_get_irqchip_state(), and irq_set_irqchip_state() [the functions, not the callbacks] have the interesting property that they search up the irqdomain hierarchy for the first irqdomain with the callback. So if all the callback would do is defer to its parent, it doesn't need to be provided at all*. *except in case this irqdomain has a child which calls irq_chip_get_parent_state(), which does not look past its immediate parent. But I did not think that case was worth worrying about. Cheers, Samuel > Otherwise, looks pretty good now. > > Thanks, > > M. >
WARNING: multiple messages have this Message-ID (diff)
From: Samuel Holland <samuel@sholland.org> To: Marc Zyngier <maz@kernel.org> Cc: Ondrej Jirman <megous@megous.com>, devicetree@vger.kernel.org, Jernej Skrabec <jernej.skrabec@siol.net>, linux-kernel@vger.kernel.org, Maxime Ripard <mripard@kernel.org>, Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 03/10] irqchip/sun6i-r: Use a stacked irqchip driver Date: Thu, 14 Jan 2021 22:01:59 -0600 [thread overview] Message-ID: <495f71d0-9dbf-23d2-45a1-f27b15138bb2@sholland.org> (raw) In-Reply-To: <87turjjkjr.wl-maz@kernel.org> Hello, On 1/14/21 3:06 PM, Marc Zyngier wrote: > Hi Samuel, > > On 2021-01-12 05:59, Samuel Holland wrote: > > [...] > >> +static void sun6i_r_intc_ack_nmi(void) >> +{ >> + writel(SUN6I_NMI_BIT, base + SUN6I_IRQ_PENDING(0)); > > writel_relaxed() irq_chip_unmask_parent(), which calls gic_unmask_irq(), is called immediately after this in .irq_unmask. Since gic_unmask_irq() also uses writel_relaxed(), the GIC write could be ordered before the write here. I was getting occasional spurious interrupts (1 out of each 20-25) when using a level trigger, which were resolved by switching to writel() here. I mentioned this in the changelog, but it probably deserves a comment in the code as well. Or maybe I should use an explicit barrier somewhere? >> +} >> + >> +static void sun6i_r_intc_nmi_ack(struct irq_data *data) >> +{ >> + if (irqd_get_trigger_type(data) & IRQ_TYPE_EDGE_BOTH) >> + sun6i_r_intc_ack_nmi(); >> + else >> + data->chip_data = SUN6I_NMI_NEEDS_ACK; >> +} >> + >> +static void sun6i_r_intc_nmi_eoi(struct irq_data *data) >> +{ >> + /* For oneshot IRQs, delay the ack until the IRQ is unmasked. */ >> + if (data->chip_data == SUN6I_NMI_NEEDS_ACK && !irqd_irq_masked(data)) >> { >> + sun6i_r_intc_ack_nmi(); >> + data->chip_data = 0; > > nit: NULL rather than 0? NULL seemed less appropriate since I'm not using the field as a pointer, but I don't have a strong opinion about it. > [...] > >> +static struct irq_chip sun6i_r_intc_nmi_chip = { >> + .name = "sun6i-r-intc", >> + .irq_ack = sun6i_r_intc_nmi_ack, >> + .irq_mask = irq_chip_mask_parent, >> + .irq_unmask = sun6i_r_intc_nmi_unmask, >> + .irq_eoi = sun6i_r_intc_nmi_eoi, >> + .irq_set_affinity = irq_chip_set_affinity_parent, >> + .irq_set_type = sun6i_r_intc_nmi_set_type, >> + .irq_set_irqchip_state = sun6i_r_intc_nmi_set_irqchip_state, > > You probably also want to wire irq_get_irqchip_state(), while > you're at it. I thought if the interrupt was pending here, it would necessarily also be pending at the GIC, so adding a separate layer would be redundant. irq_set_vcpu_affinity(), __irq_get_irqchip_state(), and irq_set_irqchip_state() [the functions, not the callbacks] have the interesting property that they search up the irqdomain hierarchy for the first irqdomain with the callback. So if all the callback would do is defer to its parent, it doesn't need to be provided at all*. *except in case this irqdomain has a child which calls irq_chip_get_parent_state(), which does not look past its immediate parent. But I did not think that case was worth worrying about. Cheers, Samuel > Otherwise, looks pretty good now. > > Thanks, > > M. > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-01-15 4:02 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-01-12 5:59 [PATCH v4 00/10] sunxi: Support IRQ wakeup from deep sleep Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 01/10] dt-bindings: irq: sun6i-r: Split the binding from sun7i-nmi Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-14 20:11 ` Rob Herring 2021-01-14 20:11 ` Rob Herring 2021-01-12 5:59 ` [PATCH v4 02/10] dt-bindings: irq: sun6i-r: Add a compatible for the H3 Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 03/10] irqchip/sun6i-r: Use a stacked irqchip driver Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-14 21:06 ` Marc Zyngier 2021-01-14 21:06 ` Marc Zyngier 2021-01-15 4:01 ` Samuel Holland [this message] 2021-01-15 4:01 ` Samuel Holland 2021-01-15 9:30 ` Marc Zyngier 2021-01-15 9:30 ` Marc Zyngier 2021-01-12 5:59 ` [PATCH v4 04/10] irqchip/sun6i-r: Add wakeup support Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-14 21:44 ` Marc Zyngier 2021-01-14 21:44 ` Marc Zyngier 2021-01-15 4:04 ` Samuel Holland 2021-01-15 4:04 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 05/10] ARM: dts: sunxi: Rename nmi_intc to r_intc Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 06/10] ARM: dts: sunxi: Use the new r_intc binding Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 07/10] ARM: dts: sunxi: h3/h5: Add r_intc node Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 08/10] ARM: dts: sunxi: Move wakeup-capable IRQs to r_intc Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 09/10] arm64: dts: allwinner: Use the new r_intc binding Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-12 5:59 ` [PATCH v4 10/10] arm64: dts: allwinner: Move wakeup-capable IRQs to r_intc Samuel Holland 2021-01-12 5:59 ` Samuel Holland 2021-01-14 12:16 ` [PATCH v4 00/10] sunxi: Support IRQ wakeup from deep sleep Maxime Ripard 2021-01-14 12:16 ` Maxime Ripard
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