[Skiboot] [PATCH 2/2] rtc: rtc tod state need to be updated on success

[Alistair Popple]

On Tue, 20 Jan 2015 11:43:56 Neelesh Gupta wrote:
> On 01/20/2015 05:45 AM, Jeremy Kerr wrote:
> > Hi Neelesh & Alistair,
> > 
> >> The OPAL rtc read interface currently fails as the tod state is
> >> not getting updated in the callback. The patch fixes this issue.
> >> 
> >> Signed-off-by: Neelesh Gupta <neelegup at linux.vnet.ibm.com>
> >> ---
> >> 
> >>   hw/fsp/fsp-rtc.c |    1 +
> >>   1 file changed, 1 insertion(+)
> >> 
> >> diff --git a/hw/fsp/fsp-rtc.c b/hw/fsp/fsp-rtc.c
> >> index f60d2f3..b83bb2e 100644
> >> --- a/hw/fsp/fsp-rtc.c
> >> +++ b/hw/fsp/fsp-rtc.c
> >> @@ -158,6 +158,7 @@ static void fsp_rtc_process_read(struct fsp_msg
> >> *read_resp)>> 
> >>   	case FSP_STATUS_SUCCESS:
> >>   		/* Save the read RTC value in our cache */
> >> 
> >> +		rtc_tod_state = RTC_TOD_VALID;
> >> 
> >>   		datetime_to_tm(read_resp->data.words[0],
> >>   		
> >>   			       (u64) read_resp->data.words[1] << 32, &tm);
> >>   		
> >>   		rtc_cache_update(&tm);
> > 
> > We seem to have this state in the rtc core code too
> > (rtc_tod_cache.valid) - do we need both?
> 
> 'rtc_tod_state' is required indeed, it is more discrete while
> 'rtc_tod_cache.valid'
> is a bool. So, I think both are required, but I also see that
> 'rtc_tod_cahce.valid'
> doesn't get updated, it maintains a 'true' value all the time.. probably
> that
> should be fixed separately..

rtc_tod_state is really tracking the state of the OPAL call rather than the 
state of the RTC cache. For example it is used to make sure that the RTC cache 
is updated from the FSP every time OPAL_RTC_READ is called.

rtc_tod_cache.valid is used to track if a valid time has been written into 
rtc_tod_cache.tm, which is unnecessary because it could just assume validity 
if rtc_tod_cache.tm != 0.

My eventual plan was to make a platform hook to get the current rtc value and 
implement a more fully featured cache that would keep itself updated according 
to some kind of policy rather than just updating it occasionally when 
OPAL_RTC_READ is called.

Regards,

Alistair

> - Neelesh
> 
> > Cheers,
> > 
> > 
> > Jeremy