Congatec's QMX6 system on module (SoM) uses a m41t62 as RTC. The modules SQW clock output defaults to 32768 Hz. This behaviour is used to provide the i.MX6 CKIL clock. Once the RTC driver is probed, the clock is disabled and all i.MX6 functionality depending on the 32 KHz clock have undefined behaviour (e.g. the hardware watchdog run to fast or slow). The normal solution would be to properly describe the clock tree in DT, but from the kernel's perspective this is a chicken-and-egg problem: CKIL is required very early, but the clock is only provided after the I2C RTC has been probed. Technically everything is fine by not touching anything, so this works around the issue by disabling the clock handling from the RTC driver. I guess the proper solution would be to simply mark the clock as always-enabled, but this does not seem to be supported by the clock framework. Signed-off-by: Sebastian Reichel <sebastian.reichel@xxxxxxxxxxxxx> --- Hi, This is a downstream workaround/hack for the issue described in the commit message. I would like to upstream a board based on Congatec's QMX6, which requires a proper solution for this. Do you think it would be ok to have an always-on flag for clocks similar to regulators? -- Sebastian --- drivers/rtc/rtc-m41t80.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/rtc/rtc-m41t80.c b/drivers/rtc/rtc-m41t80.c index 5f46f85f814b..81743d93d03e 100644 --- a/drivers/rtc/rtc-m41t80.c +++ b/drivers/rtc/rtc-m41t80.c @@ -973,7 +973,7 @@ static int m41t80_probe(struct i2c_client *client, } } #endif -#ifdef CONFIG_COMMON_CLK +#if 0 if (m41t80_data->features & M41T80_FEATURE_SQ) m41t80_sqw_register_clk(m41t80_data); #endif -- 2.24.0.rc1
