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| author | Troy Kisky <troy.kisky@boundarydevices.com> | 2017-11-03 02:58:15 +0100 |
|---|---|---|
| committer | Alexandre Belloni <alexandre.belloni@free-electrons.com> | 2017-11-08 07:52:24 +0100 |
| commit | 13bb1d78f2e372ec0d9b30489ac63768240140fc (patch) | |
| tree | b8fad55d3f307c4d7e3802d66935bf5841c849e8 /drivers/rtc | |
| parent | rtc: m41t80: avoid i2c read in m41t80_sqw_recalc_rate (diff) | |
| download | linux-13bb1d78f2e372ec0d9b30489ac63768240140fc.tar.xz linux-13bb1d78f2e372ec0d9b30489ac63768240140fc.zip | |
rtc: m41t80: avoid i2c read in m41t80_sqw_is_prepared
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>
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/rtc-m41t80.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index f44dcf628c87..96a606d5f6e6 100644 --- 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_hw *hw, bool enable) 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 clk_hw *hw) 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 = { |