Linux-Serial Archive on lore.kernel.org
 help / color / Atom feed
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Mikulas Patocka <mpatocka@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Richard Henderson <rth@twiddle.net>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	Matt Turner <mattst88@gmail.com>,
	alpha <linux-alpha@vger.kernel.org>,
	Sinan Kaya <okaya@codeaurora.org>,
	linux-serial@vger.kernel.org, linux-rtc@vger.kernel.org
Subject: Re: [PATCH 1/2 v3] alpha: add a delay to inb_p, inb_w and inb_l
Date: Thu, 7 May 2020 10:20:07 +0200
Message-ID: <20200507082007.GD1024567@kroah.com> (raw)
In-Reply-To: <alpine.LRH.2.02.2005070404420.5006@file01.intranet.prod.int.rdu2.redhat.com>

On Thu, May 07, 2020 at 04:06:31AM -0400, Mikulas Patocka wrote:
> 
> 
> On Wed, 6 May 2020, Mikulas Patocka wrote:
> 
> > 
> > 
> > On Wed, 6 May 2020, Arnd Bergmann wrote:
> > 
> > > On Wed, May 6, 2020 at 1:21 PM Mikulas Patocka <mpatocka@redhat.com> wrote:
> > > 
> > > >  /*
> > > >   * The yet supported machines all access the RTC index register via
> > > >   * an ISA port access but the way to access the date register differs ...
> > > > + *
> > > > + * The ISA bus on Alpha Avanti doesn't like back-to-back accesses,
> > > > + * we need to add a small delay.
> > > >   */
> > > >  #define CMOS_READ(addr) ({ \
> > > >  outb_p((addr),RTC_PORT(0)); \
> > > > +udelay(2); \
> > > >  inb_p(RTC_PORT(1)); \
> > > 
> > > 
> > > The inb_p() / outb_p() functions are meant to already have a delay in them,
> > > maybe we should just add it there for alpha?
> > > 
> > >      Arnd
> > 
> > Yes, that is possible too - it fixes the real time clock hang for me.
> > 
> > 
> > -#define inb_p		inb
> > -#define inw_p		inw
> > -#define inl_p		inl
> > +#define inb_p(x)	(ndelay(300), inb(x))
> > +#define inw_p(x)	(ndelay(300), inw(x))
> > +#define inl_p(x)	(ndelay(300), inl(x))
> >  #define outb_p		outb
> >  #define outw_p		outw
> >  #define outl_p		outl
> 
> 300ns was too low. We need at least 1400ns to fix the hang reliably.
> 
> Mikulas
> 
> 
> From: Mikulas Patocka <mpatocka@redhat.com>
> 
> The patch 92d7223a74235054f2aa7227d207d9c57f84dca0 ("alpha: io: reorder
> barriers to guarantee writeX() and iowriteX() ordering #2") broke boot on
> the Alpha Avanti platform.
> 
> The patch changes timing between accesses to the ISA bus, in particular,
> it reduces the time between "write" access and a subsequent "read" access.
> 
> This causes lock-up when accessing the real time clock and serial ports.
> 
> This patch fixes the real time clock by adding a small delay to the inb_p,
> inw_p and inl_p macros.
> 
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
> Fixes: 92d7223a7423 ("alpha: io: reorder barriers to guarantee writeX() and iowriteX() ordering #2")
> Cc: stable@vger.kernel.org	# v4.17+
> 
> ---
>  arch/alpha/include/asm/io.h |    7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)

<snip>

This is not in a format that anyone can apply it in, please resend in a
proper way if you wish for it to be accepted.

thanks,

greg k-h

  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-06 11:21 [PATCH 1/2] alpha: add a delay between RTC port write and read Mikulas Patocka
2020-05-06 14:20 ` Arnd Bergmann
2020-05-06 17:12   ` [PATCH 1/2 v2] alpha: add a delay to inb_p, inb_w and inb_l Mikulas Patocka
2020-05-07  8:06     ` [PATCH 1/2 v3] " Mikulas Patocka
2020-05-07  8:20       ` Greg Kroah-Hartman [this message]
2020-05-07 10:53         ` Mikulas Patocka
2020-05-07 13:30       ` Arnd Bergmann
2020-05-07 14:09         ` Mikulas Patocka
2020-05-07 15:08           ` Arnd Bergmann
2020-05-07 15:45             ` Mikulas Patocka
2020-05-07 15:46             ` [PATCH v4] alpha: add a barrier after outb, outw and outl Mikulas Patocka
2020-05-07 19:12               ` Arnd Bergmann
2020-05-10  1:27                 ` Maciej W. Rozycki
2020-05-10  1:25             ` [PATCH 1/2 v3] alpha: add a delay to inb_p, inb_w and inb_l Maciej W. Rozycki
2020-05-10 18:50               ` Mikulas Patocka
2020-05-11 14:58                 ` Maciej W. Rozycki
2020-05-12 19:35                   ` Mikulas Patocka
2020-05-13 14:41                   ` Ivan Kokshaysky
2020-05-13 16:13                     ` Greg Kroah-Hartman
2020-05-13 17:17                     ` Maciej W. Rozycki
2020-05-22 13:03                       ` Mikulas Patocka
2020-05-22 13:37                         ` Maciej W. Rozycki
2020-05-22 13:26                     ` Mikulas Patocka
2020-05-22 20:00                       ` Mikulas Patocka
2020-05-23 10:26                         ` [PATCH v4] alpha: fix memory barriers so that they conform to the specification Mikulas Patocka
2020-05-23 15:10                           ` Ivan Kokshaysky
2020-05-23 15:34                             ` Mikulas Patocka
2020-05-23 15:37                               ` [PATCH v5] " Mikulas Patocka
2020-05-24 14:54                                 ` Maciej W. Rozycki
2020-05-25 13:56                                   ` Mikulas Patocka
2020-05-25 14:07                                     ` Arnd Bergmann
2020-05-25 14:45                                     ` Maciej W. Rozycki
2020-05-25 15:53                                       ` [PATCH v6] " Mikulas Patocka
2020-05-26 14:47                                         ` [PATCH v7] " Mikulas Patocka
2020-05-27  0:18                                           ` Maciej W. Rozycki
2020-06-08  6:58                                             ` Mikulas Patocka
2020-06-08 23:49                                               ` Matt Turner
2020-05-25 15:54                                       ` [PATCH v5] " Mikulas Patocka
2020-05-25 16:39                                         ` Maciej W. Rozycki
2020-05-26 14:48                                           ` Mikulas Patocka
2020-05-27  0:23                                             ` Maciej W. Rozycki
2020-05-23 16:44                               ` [PATCH v4] " Maciej W. Rozycki
2020-05-23 17:09                                 ` Mikulas Patocka
2020-05-23 19:27                                   ` Maciej W. Rozycki
2020-05-23 20:11                                     ` Mikulas Patocka

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=20200507082007.GD1024567@kroah.com \
    --to=gregkh@linuxfoundation.org \
    --cc=arnd@arndb.de \
    --cc=ink@jurassic.park.msu.ru \
    --cc=linux-alpha@vger.kernel.org \
    --cc=linux-rtc@vger.kernel.org \
    --cc=linux-serial@vger.kernel.org \
    --cc=mattst88@gmail.com \
    --cc=mpatocka@redhat.com \
    --cc=okaya@codeaurora.org \
    --cc=rth@twiddle.net \
    /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

Linux-Serial Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-serial/0 linux-serial/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-serial linux-serial/ https://lore.kernel.org/linux-serial \
		linux-serial@vger.kernel.org
	public-inbox-index linux-serial

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-serial


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git