[PATCH 0/3] ARM: OMAP2+: hwmod: RTC: Add lock and unlock hooks

[Paul Walmsley]

On Thu, 16 Jul 2015, Tero Kristo wrote:

> On 07/16/2015 03:15 AM, Paul Walmsley wrote:
> > On Tue, 14 Jul 2015, Tero Kristo wrote:
> > 
> > > On 07/14/2015 01:09 PM, Lokesh Vutla wrote:
> > > > Hi,
> > > > On Wednesday 10 June 2015 02:56 PM, Lokesh Vutla wrote:
> > > > > Some IP blocks like RTC, needs an additional unlocking mechanism for
> > > > > writing to its registers. This patch adds optional lock and unlock
> > > > > function pointers to the IP block's hwmod data which gets executed
> > > > > before and after writing into IP sysconfig register.
> > > > > And also hook lock and unlock functions to AMx3xx, DRA7 RTC hwmod
> > > > > data,
> > > > > so that sysconfig registers are updated properly.
> > > > ping on this series.
> > > > 
> > > > Thanks and regards,
> > > > Lokesh
> > > 
> > 
> > [...]
> > 
> > > It is also racy, as there is no locking in place to avoid concurrent
> > > access to
> > > the lock/unlock registers across hwmod+driver.
> > 
> > I don't see the race.  Where is it?
> 
> See drivers/rtc/rtc-omap.c, am3352_rtc_unlock and am3352_rtc_lock.
> 
> That code is accessing the exact same registers.

I guess my question is, when is it possible that code could race with the 
hwmod code for the same device?


- Paul