From: Mikulas Patocka <mpatocka@redhat.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Richard Henderson <rth@twiddle.net>,
Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
Matt Turner <mattst88@gmail.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
alpha <linux-alpha@vger.kernel.org>,
Sinan Kaya <okaya@codeaurora.org>,
linux-serial@vger.kernel.org, linux-rtc@vger.kernel.org
Subject: [PATCH 1/2 v3] alpha: add a delay to inb_p, inb_w and inb_l
Date: Thu, 7 May 2020 04:06:31 -0400 (EDT) [thread overview]
Message-ID: <alpine.LRH.2.02.2005070404420.5006@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <alpine.LRH.2.02.2005061308220.18599@file01.intranet.prod.int.rdu2.redhat.com>
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(-)
Index: linux-stable/arch/alpha/include/asm/io.h
===================================================================
--- linux-stable.orig/arch/alpha/include/asm/io.h 2020-05-07 09:54:52.000000000 +0200
+++ linux-stable/arch/alpha/include/asm/io.h 2020-05-07 09:54:52.000000000 +0200
@@ -6,6 +6,7 @@
#include <linux/kernel.h>
#include <linux/mm.h>
+#include <linux/delay.h>
#include <asm/compiler.h>
#include <asm/pgtable.h>
#include <asm/machvec.h>
@@ -481,9 +482,9 @@ extern inline void writeq(u64 b, volatil
#define iowrite16be(v,p) iowrite16(cpu_to_be16(v), (p))
#define iowrite32be(v,p) iowrite32(cpu_to_be32(v), (p))
-#define inb_p inb
-#define inw_p inw
-#define inl_p inl
+#define inb_p(x) (ndelay(1400), inb(x))
+#define inw_p(x) (ndelay(1400), inw(x))
+#define inl_p(x) (ndelay(1400), inl(x))
#define outb_p outb
#define outw_p outw
#define outl_p outl
next prev parent reply other threads:[~2020-05-07 8:06 UTC|newest]
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 ` Mikulas Patocka [this message]
2020-05-07 8:20 ` [PATCH 1/2 v3] " Greg Kroah-Hartman
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
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