From: Jean Delvare <jdelvare@suse.de>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>,
linux-acpi@vger.kernel.org,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Guenter Roeck <linux@roeck-us.net>,
linux-watchdog@vger.kernel.org,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Tom Abraham <tabraham@suse.com>
Subject: wdat_wdt: access width inconsistency
Date: Mon, 10 Feb 2020 11:16:38 +0100 [thread overview]
Message-ID: <20200210111638.64925c8e@endymion> (raw)
Hi all,
I'm still working on my customer issue where the wdat_wdt driver
reboots the server instantly as soon as the watchdog daemon is started.
I looked at all the upstream fixes and we already have all relevant
ones in our kernel so I start suspecting either a driver bug or a BIOS
issue.
While reading the driver code I noticed one suspect thing related to
the register access width, which I'd like a second opinion on.
Both acpi_watchdog.c and wdat_wdt.c contain code like:
res.end = res.start + gas->access_width - 1;
This suggests that gas->access_width is expected to be 4 in case of a
32-bit register. However in wdat_wdt_read/wdat_wdt_write we have:
switch (gas->access_width) {
(...)
case 3:
*value = ioread32(instr->reg);
This looks inconsistent to me.
My reading of the ACPI specification suggests that 3 is the right value
for 32-bit registers. If so, then shouldn't the resource's end be set
to:
res.end = res.start + (1 << (gas->access_width - 1)) - 1;
?
Thanks,
--
Jean Delvare
SUSE L3 Support
next reply other threads:[~2020-02-10 10:16 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 10:16 Jean Delvare [this message]
2020-02-10 11:23 ` wdat_wdt: access width inconsistency Mika Westerberg
2020-02-11 13:11 ` Jean Delvare
2020-02-11 13:59 ` Mika Westerberg
2020-02-11 16:25 ` Jean Delvare
2020-02-11 16:37 ` Mika Westerberg
2020-02-11 17:03 ` Jean Delvare
2020-02-12 11:05 ` [PATCH 1/3] ACPICA: Introduce ACPI_ACCESS_BIT_WIDTH() macro Mika Westerberg
2020-02-12 11:05 ` [PATCH 2/3] ACPI / watchdog: Fix gas->access_width usage Mika Westerberg
2020-02-12 11:56 ` Jean Delvare
2020-02-12 12:10 ` Mika Westerberg
2020-02-12 11:05 ` [PATCH 3/3] ACPI / watchdog: Set default timeout in probe Mika Westerberg
2020-02-12 12:07 ` Jean Delvare
2020-02-12 12:13 ` Mika Westerberg
2020-02-12 11:52 ` [PATCH 1/3] ACPICA: Introduce ACPI_ACCESS_BIT_WIDTH() macro Jean Delvare
2020-02-12 12:08 ` Mika Westerberg
2020-02-11 16:45 ` wdat_wdt: access width inconsistency Guenter Roeck
2020-02-12 10:30 ` Jean Delvare
2020-02-12 10:47 ` Mika Westerberg
2020-02-12 11:05 ` Jean Delvare
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