All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Alexandre Oliva <lxoliva@fsfla.org>, Tom Li <tomli@tomli.me>,
	James Hogan <jhogan@kernel.org>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	Huacai Chen <chenhc@lemote.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] On the Current Troubles of Mainlining Loongson Platform Drivers
Date: Wed, 12 Jun 2019 06:55:28 +0100 (BST)	[thread overview]
Message-ID: <alpine.LFD.2.21.1906102253080.19418@eddie.linux-mips.org> (raw)
In-Reply-To: <20190610214938.GB7147@darkstar.musicnaut.iki.fi>

On Tue, 11 Jun 2019, Aaro Koskinen wrote:

> However, with your patch the "nobody cared" is never reached so all is
> good. I tried 10 boots with the patch and all were successful. Without
> the patch 8 out of 10 failed with the "nobody cared" warning.

 I wouldn't call it "good", just less obvious or painful.  This is still 
causing wasted CPU cycles that are used for taking the phantom interrupts.

 There is clearly a completion barrier missing somewhere that causes the 
interrupt request to linger beyond the point interrupts are reenabled at 
the CPU.

 One way to attempt to narrow it down might be taking a backtrace from 
where IRQ 14 is found to be spurious.  This would indicate the offending 
interrupt unmask action.  E.g. I see no explicit completion barrier 
between the final `outb' in `mask_and_ack_8259A' and the following call to 
`raw_spin_unlock_irqrestore', which are obviously otherwise unordered WRT 
each other (because `outb' is I/O or MMIO and `raw_spin_unlock_irqrestore' 
is contained within the CPU on UP).  I can see provisions however for 
issuing an architecture-specific barrier in `do_raw_spin_unlock', which is 
the workhorse for `raw_spin_unlock_irqrestore', so maybe this is the place 
to look into?

 Also how's IRQ 14 registered as indicated by /proc/interrupts?

  Maciej

  reply	other threads:[~2019-06-12  5:55 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-08  8:30 [RFC] On the Current Troubles of Mainlining Loongson Platform Drivers Tom Li
2019-02-08 20:08 ` Paul Burton
2019-02-09 10:11   ` Tom Li
2019-02-09 19:38     ` Paul Burton
2019-02-11 12:13 ` Alexandre Oliva
2019-02-11 12:55   ` Tom Li
2019-02-11 22:38     ` Alexandre Oliva
2019-02-11 23:06       ` Aaro Koskinen
2019-02-12  4:39         ` tomli
2019-02-16 23:39         ` Alexandre Oliva
2019-02-17  4:59         ` Alexandre Oliva
2019-02-17 23:59           ` Aaro Koskinen
2019-02-18  1:37             ` Alexandre Oliva
2019-02-18  2:41               ` Maciej W. Rozycki
2019-03-07  6:41                 ` Alexandre Oliva
2019-03-07 17:59                   ` Maciej W. Rozycki
2019-03-08  0:46                     ` Alexandre Oliva
2019-03-08 23:56                       ` Maciej W. Rozycki
2019-05-26  9:19                         ` Alexandre Oliva
2019-06-10 21:49                           ` Aaro Koskinen
2019-06-12  5:55                             ` Maciej W. Rozycki [this message]
2019-06-12 19:24                               ` Aaro Koskinen
2020-01-23  0:20                                 ` Matt Turner
2020-01-24 18:58                                   ` Aaro Koskinen
2019-03-07 20:21                   ` Aaro Koskinen
2019-03-07 21:22                     ` Alexandre Oliva
2019-02-17  4:41     ` Alexandre Oliva

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=alpine.LFD.2.21.1906102253080.19418@eddie.linux-mips.org \
    --to=macro@linux-mips.org \
    --cc=aaro.koskinen@iki.fi \
    --cc=chenhc@lemote.com \
    --cc=jhogan@kernel.org \
    --cc=jiaxun.yang@flygoat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mips@vger.kernel.org \
    --cc=lxoliva@fsfla.org \
    --cc=ralf@linux-mips.org \
    --cc=tomli@tomli.me \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.