This is a note to let you know that I've just added the patch titled
rtc: m41t80: avoid i2c read in m41t80_sqw_is_prepared
to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: rtc-m41t80-avoid-i2c-read-in-m41t80_sqw_is_prepared.patch and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From 13bb1d78f2e372ec0d9b30489ac63768240140fc Mon Sep 17 00:00:00 2001
From: Troy Kisky troy.kisky@boundarydevices.com Date: Thu, 2 Nov 2017 18:58:15 -0700 Subject: rtc: m41t80: avoid i2c read in m41t80_sqw_is_prepared
From: Troy Kisky troy.kisky@boundarydevices.com
commit 13bb1d78f2e372ec0d9b30489ac63768240140fc upstream.
This is a little more efficient and avoids the warning
WARNING: possible circular locking dependency detected 4.14.0-rc7-00010 #16 Not tainted ------------------------------------------------------ kworker/2:1/70 is trying to acquire lock: (prepare_lock){+.+.}, at: [<c049300c>] clk_prepare_lock+0x80/0xf4
but task is already holding lock: (i2c_register_adapter){+.+.}, at: [<c0690b04>] i2c_adapter_lock_bus+0x14/0x18
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (i2c_register_adapter){+.+.}: rt_mutex_lock+0x44/0x5c i2c_adapter_lock_bus+0x14/0x18 i2c_transfer+0xa8/0xbc i2c_smbus_xfer+0x20c/0x5d8 i2c_smbus_read_byte_data+0x38/0x48 m41t80_sqw_is_prepared+0x18/0x28
Signed-off-by: Troy Kisky troy.kisky@boundarydevices.com Signed-off-by: Alexandre Belloni alexandre.belloni@free-electrons.com Cc: Christoph Fritz chf.fritz@googlemail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/rtc/rtc-m41t80.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-)
--- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -155,6 +155,7 @@ struct m41t80_data { #ifdef CONFIG_COMMON_CLK struct clk_hw sqw; unsigned long freq; + unsigned int sqwe; #endif };
@@ -527,7 +528,10 @@ static int m41t80_sqw_control(struct clk else ret &= ~M41T80_ALMON_SQWE;
- return i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret); + ret = i2c_smbus_write_byte_data(client, M41T80_REG_ALARM_MON, ret); + if (!ret) + m41t80->sqwe = enable; + return ret; }
static int m41t80_sqw_prepare(struct clk_hw *hw) @@ -542,14 +546,7 @@ static void m41t80_sqw_unprepare(struct
static int m41t80_sqw_is_prepared(struct clk_hw *hw) { - struct m41t80_data *m41t80 = sqw_to_m41t80_data(hw); - struct i2c_client *client = m41t80->client; - int ret = i2c_smbus_read_byte_data(client, M41T80_REG_ALARM_MON); - - if (ret < 0) - return ret; - - return !!(ret & M41T80_ALMON_SQWE); + return sqw_to_m41t80_data(hw)->sqwe; }
static const struct clk_ops m41t80_sqw_ops = {
Patches currently in stable-queue which might be from troy.kisky@boundarydevices.com are
queue-4.14/rtc-m41t80-m41t80_sqw_set_rate-should-return-0-on-success.patch queue-4.14/rtc-m41t80-avoid-i2c-read-in-m41t80_sqw_is_prepared.patch queue-4.14/rtc-m41t80-avoid-i2c-read-in-m41t80_sqw_recalc_rate.patch queue-4.14/rtc-m41t80-remove-unneeded-checks-from-m41t80_sqw_set_rate.patch queue-4.14/rtc-m41t80-fix-m41t80_sqw_round_rate-return-value.patch