Re: [PATCH] rtc: cmos: Do not export alarm rtc_ops when we do not support alarms

[Alexandre Belloni <alexandre.belloni@free-electrons.com>]

On 04/09/2018 16:51:29+0200, Hans de Goede wrote:
> When there is no IRQ configured for the RTC, the rtc-cmos code does not
> support alarms, all alarm rtc_ops fail with -EIO / -EINVAL.
> 
> The rtc-core expects a rtc driver which does not support rtc alarms to
> not have alarm ops at all. Otherwise the wakealarm sysfs attr will read
> as empty rather then returning an error, making it impossible for
> userspace to find out beforehand if alarms are supported.
> 
> A system without an IRQ for the RTC before this patch:
> [root@localhost ~]# cat /sys/class/rtc/rtc0/wakealarm
> [root@localhost ~]#
> 
> After this patch:
> [root@localhost ~]# cat /sys/class/rtc/rtc0/wakealarm
> cat: /sys/class/rtc/rtc0/wakealarm: No such file or directory
> [root@localhost ~]#
> 
> This fixes gnome-session + systemd trying to use suspend-then-hibernate,
> which causes systemd to abort the suspend when writing the RTC alarm fails.
> 
> BugLink: https://github.com/systemd/systemd/issues/9988
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
>  drivers/rtc/rtc-cmos.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
Applied, thanks.

However, you must be using an ancient kernel as my email address changed
a while ago ;)

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com