From: Stefan Wahren <stefan.wahren@i2se.com>
To: Lukas Wunner <lukas@wunner.de>, Marc Zyngier <maz@kernel.org>,
Florian Fainelli <f.fainelli@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Jason Cooper <jason@lakedaemon.net>,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
Ray Jui <rjui@broadcom.com>,
Scott Branden <sbranden@broadcom.com>,
bcm-kernel-feedback-list@broadcom.com,
linux-kernel@vger.kernel.org,
linux-rpi-kernel@lists.infradead.org,
linux-arm-kernel@lists.infradead.org,
Serge Schneider <serge@raspberrypi.org>,
Kristina Brooks <notstina@gmail.com>,
Matthias Brugger <mbrugger@suse.com>,
Martin Sperl <kernel@martin.sperl.org>,
Phil Elwell <phil@raspberrypi.org>
Subject: Re: [PATCH v2] irqchip/bcm2835: Quiesce IRQs left enabled by bootloader
Date: Sun, 23 Feb 2020 18:59:56 +0100 [thread overview]
Message-ID: <61cc6b74-3dd2-38d0-6da0-eb3fbd87c598@i2se.com> (raw)
In-Reply-To: <20200212123651.apio6kno2cqhcskb@wunner.de>
Hi Lukas,
Am 12.02.20 um 13:36 schrieb Lukas Wunner:
> On Tue, Feb 11, 2020 at 08:47:05PM -0800, Florian Fainelli wrote:
>> The commit message is a bit long and starts
>> going into details that I am not sure add anything
> I adhere to the school of thought which holds that commit messages
> shall provide complete context, including numbers to back up claims,
> user-visible impact, affected versions, genesis of the fix and so on.
> By that logic there's no such a thing as a too long commit message.
>
> Nevertheless please find a shortened version below, complete with
> the Fixes tag you requested as well as your R-b.
>
>
> On Wed, Feb 12, 2020 at 08:13:29AM +0000, Marc Zyngier wrote:
>> It otherwise looks good. You can either resend it with a fixed commit
>> message,
>> or provide me with a commit message that I can stick there while applying
>> it.
> The below also contains the patch itself, so can be applied directly
> with git am --scissors. Feel free to tweak as you see fit.
> Shout if I've missed anything. Thanks.
thanks for all the investigation. Unfortunately the patch below doesn't
compile, since it lacks the definiton of REG_FIQ_ENABLE.
Btw the name is a little bit unlucky because it defines a single flag
within REG_FIQ_CONTROL instead of a separate register.
Regards
Stefan
>
> -- >8 --
> From: Lukas Wunner <lukas@wunner.de>
> Subject: [PATCH] irqchip/bcm2835: Quiesce IRQs left enabled by bootloader
>
> Per the spec, the BCM2835's IRQs are all disabled when coming out of
> power-on reset. Its IRQ driver assumes that's still the case when the
> kernel boots and does not perform any initialization of the registers.
> However the Raspberry Pi Foundation's bootloader leaves the USB
> interrupt enabled when handing over control to the kernel.
>
> Quiesce IRQs and the FIQ if they were left enabled and log a message to
> let users know that they should update the bootloader once a fixed
> version is released.
>
> If the USB interrupt is not quiesced and the USB driver later on claims
> the FIQ (as it does on the Raspberry Pi Foundation's downstream kernel),
> interrupt latency for all other peripherals increases and occasional
> lockups occur. That's because both the FIQ and the normal USB interrupt
> fire simultaneously.
>
> On a multicore Raspberry Pi, if normal interrupts are routed to CPU 0
> and the FIQ to CPU 1 (hardcoded in the Foundation's kernel), then a USB
> interrupt causes CPU 0 to spin in bcm2836_chained_handle_irq() until the
> FIQ on CPU 1 has cleared it. Other peripherals' interrupts are starved
> as long. I've seen CPU 0 blocked for up to 2.9 msec. eMMC throughput
> on a Compute Module 3 irregularly dips to 23.0 MB/s without this commit
> but remains relatively constant at 23.5 MB/s with this commit.
>
> The lockups occur when CPU 0 receives a USB interrupt while holding a
> lock which CPU 1 is trying to acquire while the FIQ is temporarily
> disabled on CPU 1. At best users get RCU CPU stall warnings, but most
> of the time the system just freezes.
>
> Fixes: 89214f009c1d ("ARM: bcm2835: add interrupt controller driver")
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
> Cc: stable@vger.kernel.org # v3.7+
> Cc: Serge Schneider <serge@raspberrypi.org>
> Cc: Kristina Brooks <notstina@gmail.com>
> ---
> drivers/irqchip/irq-bcm2835.c | 14 ++++++++++++++
> 1 file changed, 14 insertions(+)
>
> diff --git a/drivers/irqchip/irq-bcm2835.c b/drivers/irqchip/irq-bcm2835.c
> index 418245d..eca9ac7 100644
> --- a/drivers/irqchip/irq-bcm2835.c
> +++ b/drivers/irqchip/irq-bcm2835.c
> @@ -135,6 +135,7 @@ static int __init armctrl_of_init(struct device_node *node,
> {
> void __iomem *base;
> int irq, b, i;
> + u32 reg;
>
> base = of_iomap(node, 0);
> if (!base)
> @@ -157,6 +158,19 @@ static int __init armctrl_of_init(struct device_node *node,
> handle_level_irq);
> irq_set_probe(irq);
> }
> +
> + reg = readl_relaxed(intc.enable[b]);
> + if (reg) {
> + writel_relaxed(reg, intc.disable[b]);
> + pr_err(FW_BUG "Bootloader left irq enabled: "
> + "bank %d irq %*pbl\n", b, IRQS_PER_BANK, ®);
> + }
> + }
> +
> + reg = readl_relaxed(base + REG_FIQ_CONTROL);
> + if (reg & REG_FIQ_ENABLE) {
> + writel_relaxed(0, base + REG_FIQ_CONTROL);
> + pr_err(FW_BUG "Bootloader left fiq enabled\n");
> }
>
> if (is_2836) {
next prev parent reply other threads:[~2020-02-23 18:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-07 15:46 [PATCH] irqchip/bcm2835: Quiesce IRQs left enabled by bootloader Lukas Wunner
2020-02-07 16:11 ` Marc Zyngier
2020-02-10 9:52 ` [PATCH v2] " Lukas Wunner
2020-02-12 4:47 ` Florian Fainelli
2020-02-12 8:13 ` Marc Zyngier
2020-02-12 12:36 ` Lukas Wunner
2020-02-12 12:55 ` Nicolas Saenz Julienne
2020-02-23 17:59 ` Stefan Wahren [this message]
2020-02-23 18:24 ` Lukas Wunner
2020-02-24 9:21 ` Stefan Wahren
2020-02-25 9:50 ` [PATCH v4] " Lukas Wunner
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Lukas Wunner
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