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Date: Tue, 10 Apr 2007 14:23:01 +0200 From: Jean Delvare <khali@...ux-fr.org> To: Christian Kujau <christian@...ouse.de> Cc: linux-kernel@...r.kernel.org Subject: Re: w83l785ts: Couldn't read value from register Hallo Christian, On Mon, 9 Apr 2007 20:21:57 +0100 (BST), Christian Kujau wrote: > I've got this Asus A7N8X-X board and when using lm-sensors, these > messages occasionally show up in my kernel logs: > > w83l785ts 1-002e: Couldn't read value from register 0x53. Please report. Is it always this same register failing, or 0x27 too? How frequently do the failures happen? Is there any pattern in the time at which the failures happen? > ...and reporting is what I do with this email :) > Please see .config, dmidecode and more right here: > http://nerdbynature.de/bits/w83l785ts/ Thanks for reporting. I didn't remember I had put this request in the source code ;) Unfortunately this motherboard is famous for these read errors. I still don't know what is causing them, BTW. Could be concurrent access by ACPI or SMM, or maybe the W83L785TS-S chip is weak and/or improperly wired on the board. I seem to remember that the board has an Asus ASB100 hardware monitoring chip too, and that this one doesn't have read failures? This suggests that the problem is really with the W83L785TS-S itself and not the SMBus master. Can you please add your /proc/ioports and /proc/acpi/dsdt files to the location above? I'd like to take a look. > I suppose the message is informational anyway, since sensors(1) is > working fine. On read error, the driver will present the previous reading to user-space. So it is expected that you don't notice anything. > Perhaps we can silence the printk to only show up when > some debug-option is toggled? No, informational messages are _already_ only printed when debugging is enabled. The message you reported is printed when all the retries were exhausted without success. The hope was that it wouldn't happen, and in fact we didn't have any report for a couple years now. There probably isn't much we can do, except increasing the delay or the retry count, and hope it'll be sufficient. Can you please try the following patch and see if it helps? Wait longer between read retries. Signed-off-by: Jean Delvare <khali@...ux-fr.org> --- drivers/hwmon/w83l785ts.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- linux-2.6.21-rc6.orig/drivers/hwmon/w83l785ts.c 2007-02-10 13:41:27.000000000 +0100 +++ linux-2.6.21-rc6/drivers/hwmon/w83l785ts.c 2007-04-10 14:16:50.000000000 +0200 @@ -1,7 +1,7 @@ /* * w83l785ts.c - Part of lm_sensors, Linux kernel modules for hardware * monitoring - * Copyright (C) 2003-2004 Jean Delvare <khali@...ux-fr.org> + * Copyright (C) 2003-2007 Jean Delvare <khali@...ux-fr.org> * * Inspired from the lm83 driver. The W83L785TS-S is a sensor chip made * by Winbond. It reports a single external temperature with a 1 deg @@ -298,12 +298,13 @@ static u8 w83l785ts_read_value(struct i2 "0x%02x.\n", value, reg); return value; } - dev_dbg(&client->dev, "Read failed, will retry in %d.\n", i); - msleep(i); + dev_dbg(&client->dev, "Read failed, will retry in %d ms\n", + i*4); + msleep(i*4); } - dev_err(&client->dev, "Couldn't read value from register 0x%02x. " - "Please report.\n", reg); + dev_err(&client->dev, "Couldn't read value from register 0x%02x\n", + reg); return defval; } -- Jean Delvare - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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