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From: Grazvydas Ignotas <notasas@gmail.com>
To: Lars-Peter Clausen <lars@metafoo.de>
Cc: Anton Vorontsov <cbouatmailru@gmail.com>,
	Pali Rohar <pali.rohar@gmail.com>,
	Rodolfo Giometti <giometti@linux.it>,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/14 v3] bq27x00: Cache battery registers
Date: Wed, 16 Feb 2011 00:39:35 +0200	[thread overview]
Message-ID: <AANLkTik6df6X2Jw8m6SYCFi9aN2LZc=C72WCw=gDevOr@mail.gmail.com> (raw)
In-Reply-To: <AANLkTi=RJfYEoiCPgesmZUoeOy+MehZQWeWDCWoW7vnh@mail.gmail.com>

[-- Attachment #1: Type: text/plain, Size: 2104 bytes --]

On Tue, Feb 15, 2011 at 1:48 PM, Grazvydas Ignotas <notasas@gmail.com> wrote:
> On Tue, Feb 15, 2011 at 12:14 AM, Lars-Peter Clausen <lars@metafoo.de> wrote:
>> On 02/14/2011 10:58 PM, Grazvydas Ignotas wrote:
>>> This is wrong, as read function returns negative values for bq27500
>>> when discharging. That's why read function used to pass value through
>>> argument before your series (return value was for error code).
>>
>> I don't think so. The register is 16bit wide and it is read as a unsigned. So
>> in the non error case bq27x00_read will always return >= 0.
>> The value is later reinterpreted as a signed 16bit.(See the other lines you
>> quoted underneath).
>
> Hmh, right..
>
>> Did you experience any actual problem with current being wrong?
>
> Yes, the returned current values were randomly jumping between -500000
> and 600000 while the device was discharging, so I thought
> uninitialized values were being returned (this never happened before
> the series; no errors in dmesg). I'll need to debug a bit more I
> guess..

ok this series seem to trigger unrelated bug, probably due to lots of
reads when cache is being updated, the attached patch seems to help.
Feel free to integrate it or I'll send it separately after your
patches are merged.

However there is bigger problem, compiling as module and doing
insmod/rmmod/insmod causes kernel OOPS:

[  882.575714] BUG: sleeping function called from invalid context at
arch/arm/mm/fault.c:295
[  882.584350] in_atomic(): 0, irqs_disabled(): 128, pid: 1154, name: insmod
...
[  882.959930] Unable to handle kernel NULL pointer dereference at
virtual address 00000000
[  882.968444] pgd = c14c8000
[  882.977905] Internal error: Oops: 817 [#1]
...
[  883.304412] [<c007eed8>] (__queue_work+0x140/0x260) from
[<c007f044>] (queue_work_on+0x2c/0x34)
[  883.313568] [<c007f044>] (queue_work_on+0x2c/0x34) from
[<bf008390>] (bq27x00_update+0x1f8/0x220 [bq27x00_battery])
[  883.324584] [<bf008390>] (bq27x00_update+0x1f8/0x220
[bq27x00_battery]) from [<bf0084c8>] (bq27x00_battery_poll+0x14/0x48
[bq27x00_battery])

full backtrace attached.

[-- Attachment #2: backtrace --]
[-- Type: application/octet-stream, Size: 18766 bytes --]

[-- Attachment #3: 0001-bq27x00-Use-single-i2c_transfer-call-for-property-re.patch --]
[-- Type: text/x-diff, Size: 1651 bytes --]

From 8fc5bdaf033d834d1728cd70c240d31bc457336c Mon Sep 17 00:00:00 2001
From: Grazvydas Ignotas <notasas@gmail.com>
Date: Tue, 15 Feb 2011 23:27:35 +0200
Subject: [PATCH] bq27x00: Use single i2c_transfer call for property read

Doing this by using 2 calls sometimes results in unexpected
values being returned on OMAP3 i2c controller.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
---
 drivers/power/bq27x00_battery.c |   27 +++++++++++----------------
 1 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c
index 740a0ac..59e68db 100644
--- a/drivers/power/bq27x00_battery.c
+++ b/drivers/power/bq27x00_battery.c
@@ -565,31 +565,26 @@ static DEFINE_MUTEX(battery_mutex);
 static int bq27x00_read_i2c(struct bq27x00_device_info *di, u8 reg, bool single)
 {
 	struct i2c_client *client = to_i2c_client(di->dev);
-	struct i2c_msg msg;
+	struct i2c_msg msg[2];
 	unsigned char data[2];
 	int ret;
 
 	if (!client->adapter)
 		return -ENODEV;
 
-	msg.addr = client->addr;
-	msg.flags = 0;
-	msg.len = 1;
-	msg.buf = data;
-
-	data[0] = reg;
-	ret = i2c_transfer(client->adapter, &msg, 1);
-
-	if (ret < 0)
-		return ret;
-
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].buf = &reg;
+	msg[0].len = sizeof(reg);
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = data;
 	if (single)
-		msg.len = 1;
+		msg[1].len = 1;
 	else
-		msg.len = 2;
+		msg[1].len = 2;
 
-	msg.flags = I2C_M_RD;
-	ret = i2c_transfer(client->adapter, &msg, 1);
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
 	if (ret < 0)
 		return ret;
 
-- 
1.6.3.3


  reply	other threads:[~2011-02-15 22:39 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-12 19:38 [PATCH v2 00/14] POWER: BQ27x00: New Properties, fixes, bq27000 support Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 01/14] bq27x00: Add type property Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 02/14] bq27x00: Improve temperature property precession Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 03/14] bq27x00: Fix CURRENT_NOW property Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 04/14] bq27x00: Return -ENODEV for properties if the battery is not present Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 05/14] bq27x00: Prepare code for addition of bq27000 platform driver Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 06/14] bq27x00: Add bq27000 support Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 07/14] bq27x00: Cache battery registers Lars-Peter Clausen
2011-02-13 15:14   ` Grazvydas Ignotas
2011-02-13 18:56     ` Lars-Peter Clausen
2011-02-14  3:01   ` [PATCH 07/14 v3] " Lars-Peter Clausen
2011-02-14 21:58     ` Grazvydas Ignotas
2011-02-14 22:14       ` Lars-Peter Clausen
2011-02-15 11:48         ` Grazvydas Ignotas
2011-02-15 22:39           ` Grazvydas Ignotas [this message]
2011-02-21  8:28             ` Lars-Peter Clausen
2011-02-21 14:00               ` Grazvydas Ignotas
2011-02-21 14:49                 ` Lars-Peter Clausen
2011-02-21 21:23                   ` Grazvydas Ignotas
2011-02-12 19:39 ` [PATCH v2 07/14] bq27X00: " Lars-Peter Clausen
2011-02-12 19:52   ` Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 08/14] bq27x00: Poll battery state Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 09/14] bq27x00: Add new properties Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 10/14] bq27x00: Add MODULE_DEVICE_TABLE Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 11/14] bq27x00: Give more specific reports on battery status Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 12/14] bq27x00: Minor cleanups Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 13/14] bq27x00: Cleanup bq27x00_i2c_read Lars-Peter Clausen
2011-02-12 19:39 ` [PATCH 14/14] Ignore -ENODATA errors when generating a uevent Lars-Peter Clausen

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