From: Jiaxun Yang <jiaxun.yang@flygoat.com>
To: Paul Burton <paulburton@kernel.org>
Cc: linux-mips@vger.kernel.org, chenhc@lemote.com,
paul.burton@mips.com, tglx@linutronix.de, jason@lakedaemon.net,
maz@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] irqchip: mips-cpu: Remove eoi operation
Date: Wed, 15 Jan 2020 08:03:45 +0800 [thread overview]
Message-ID: <8AEFA134-76BC-4AE9-9229-718B5C58B862@flygoat.com> (raw)
In-Reply-To: <20200114233025.y4azwvivqo7kg7i5@pburton-laptop>
于 2020年1月15日 GMT+08:00 上午7:30:25, Paul Burton <paulburton@kernel.org> 写到:
>Hi Jiaxun,
>
>On Mon, Jan 13, 2020 at 06:12:51PM +0800, Jiaxun Yang wrote:
>> The eoi opreation in mips_cpu_irq_controller caused chained_irq_enter
>> falsely consider CPU IP interrupt as a FastEOI type IRQ. So the
>interrupt
>> won't be masked during in handler. Which might lead to spurious
>interrupt.
>>
>> Thus we simply remove eoi operation for mips_cpu_irq_controller,
>>
>> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
>> ---
>> drivers/irqchip/irq-mips-cpu.c | 1 -
>> 1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/irqchip/irq-mips-cpu.c
>b/drivers/irqchip/irq-mips-cpu.c
>> index 95d4fd8f7a96..0ad7f1f9a58b 100644
>> --- a/drivers/irqchip/irq-mips-cpu.c
>> +++ b/drivers/irqchip/irq-mips-cpu.c
>> @@ -55,7 +55,6 @@ static struct irq_chip mips_cpu_irq_controller = {
>> .irq_mask = mask_mips_irq,
>> .irq_mask_ack = mask_mips_irq,
>> .irq_unmask = unmask_mips_irq,
>> - .irq_eoi = unmask_mips_irq,
>> .irq_disable = mask_mips_irq,
>> .irq_enable = unmask_mips_irq,
>> };
>
>This one scares me; something doesn't seem right. The irq_eoi (née eoi)
>callback was first added way back in commit 1417836e81c0 ("[MIPS] use
>generic_handle_irq, handle_level_irq, handle_percpu_irq"). The commit
>message there states that the motivation was to allow use of
>handle_percpu_irq(), and indeed handle_percpu_irq() does:
>
> irq_ack() (ie. mask)
> invoke the handler(s)
> irq_eoi() (ie. unmask)
>
>By removing the irq_eoi callback I don't see how we'd ever unmask the
>interrupt again..?
Hi Paul,
Sorry I didn't discover that by myself as all of my drivers are using chained handler.
So how should we deal with the chained case?
Probably we need a check in percpu IRQ handler to determine whether it's or not
level type?
>
>Thanks,
> Paul
--
Jiaxun Yang
next prev parent reply other threads:[~2020-01-15 0:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-13 10:12 [PATCH] irqchip: mips-cpu: Remove eoi operation Jiaxun Yang
2020-01-14 23:30 ` Paul Burton
2020-01-15 0:03 ` Jiaxun Yang [this message]
2020-01-15 13:40 ` Marc Zyngier
2020-01-15 14:23 ` Jiaxun Yang
2020-01-15 15:22 ` Marc Zyngier
2020-01-17 0:17 ` [PATCH v1 1/2] genirq: Check for level based percpu irq Jiaxun Yang
2020-01-17 0:17 ` [PATCH v1 2/2] irqchip: mips-cpu: Drop unnecessary ack/eoi operations Jiaxun Yang
2020-01-17 1:29 ` [PATCH v1 1/2] genirq: Check for level based percpu irq Thomas Gleixner
2020-01-17 2:23 ` Jiaxun Yang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=8AEFA134-76BC-4AE9-9229-718B5C58B862@flygoat.com \
--to=jiaxun.yang@flygoat.com \
--cc=chenhc@lemote.com \
--cc=jason@lakedaemon.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=maz@kernel.org \
--cc=paul.burton@mips.com \
--cc=paulburton@kernel.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).