5.15-stable review patch. If anyone has any objections, please let me know.
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From: Josua Mayer josua@solid-run.com
[ Upstream commit a6f1a4f05970664004a9370459c6799c1b2f2dcf ]
PCF2127 can generate interrupt every full second or minute configured from control and status register 1, bits MI (1) and SI (0).
On interrupt control register 2 bit MSF (7) is set and must be cleared to continue normal operation.
While the driver never enables this interrupt on its own, users or firmware may do so - e.g. as an easy way to test the interrupt.
Add preprocessor definition for MSF bit and include it in the irq bitmask to ensure minute and second interrupts are cleared when fired.
This fixes an issue where the rtc enters a test mode and becomes unresponsive after a second interrupt has fired and is not cleared in time. In this state register writes to control registers have no effect and the interrupt line is kept asserted [1]:
[1] userspace commands to put rtc into unresponsive state: $ i2cget -f -y 2 0x51 0x00 0x04 $ i2cset -f -y 2 0x51 0x00 0x05 # set bit 0 SI $ i2cget -f -y 2 0x51 0x00 0x84 # bit 8 EXT_TEST set $ i2cset -f -y 2 0x51 0x00 0x05 # try overwrite control register $ i2cget -f -y 2 0x51 0x00 0x84 # no change
Signed-off-by: Josua Mayer josua@solid-run.com Reviewed-by: Bruno Thomsen bruno.thomsen@gmail.com Link: https://lore.kernel.org/r/20250825-rtc-irq-v1-1-0133319406a7@solid-run.com Signed-off-by: Alexandre Belloni alexandre.belloni@bootlin.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/rtc/rtc-pcf2127.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/rtc-pcf2127.c b/drivers/rtc/rtc-pcf2127.c index 43f8011070952..f12d854d67b5e 100644 --- a/drivers/rtc/rtc-pcf2127.c +++ b/drivers/rtc/rtc-pcf2127.c @@ -35,6 +35,7 @@ #define PCF2127_BIT_CTRL2_AF BIT(4) #define PCF2127_BIT_CTRL2_TSF2 BIT(5) #define PCF2127_BIT_CTRL2_WDTF BIT(6) +#define PCF2127_BIT_CTRL2_MSF BIT(7) /* Control register 3 */ #define PCF2127_REG_CTRL3 0x02 #define PCF2127_BIT_CTRL3_BLIE BIT(0) @@ -99,7 +100,8 @@ #define PCF2127_CTRL2_IRQ_MASK ( \ PCF2127_BIT_CTRL2_AF | \ PCF2127_BIT_CTRL2_WDTF | \ - PCF2127_BIT_CTRL2_TSF2) + PCF2127_BIT_CTRL2_TSF2 | \ + PCF2127_BIT_CTRL2_MSF)
struct pcf2127 { struct rtc_device *rtc;