Re: [PATCH] ARM: omap2: drop broken broadcast timer hack

From: Tony Lindgren <tony@atomide.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Santosh Shilimkar <santosh.shilimkar@oracle.com>,
	arm-soc <arm@kernel.org>, Rob Herring <robh@kernel.org>,
	Grygorii Strashko <grygorii.strashko@ti.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Lokesh Vutla <lokeshvutla@ti.com>, Keerthy <j-keerthy@ti.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Tero Kristo <t-kristo@ti.com>, Olof Johansson <olof@lixom.net>,
	linux-omap <linux-omap@vger.kernel.org>,
	afzal mohammed <afzal.mohd.ma@gmail.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] ARM: omap2: drop broken broadcast timer hack
Date: Thu, 28 May 2020 13:38:10 -0700	[thread overview]
Message-ID: <20200528203810.GQ37466@atomide.com> (raw)
In-Reply-To: <CAK8P3a0AaH+pAdhu7jzEAGC-bECgmz7w=D8PN6NOUjj2kxevkg@mail.gmail.com>

* Arnd Bergmann <arnd@arndb.de> [200528 20:35]:
> On Thu, May 28, 2020 at 6:18 PM <santosh.shilimkar@oracle.com> wrote:
> > On 5/28/20 8:57 AM, Tony Lindgren wrote:
> > > * Tony Lindgren <tony@atomide.com> [200528 13:51]:
> > >> * Tony Lindgren <tony@atomide.com> [200528 13:47]:
> > >>> * Arnd Bergmann <arnd@arndb.de> [200528 09:20]:
> > >>>> The OMAP4 timer code had a special hack for using the broadcast timer
> > >>>> without SMP. Since the dmtimer is now gone, this also needs to be dropped
> > >>>> to avoid a link failure for non-SMP AM43xx configurations:
> > >>>>
> > >>>> kernel/time/tick-broadcast.o: in function `tick_device_uses_broadcast':
> > >>>> tick-broadcast.c:(.text+0x130): undefined reference to `tick_broadcast'
> > >>>
> > >>> Hmm this sounds like a regression though. Isn't this needed for using
> > >>> the ARM local timers on non-SMP SoC, so a separate timer from dmtimer?
> > >>>
> > >>> I've probably removed something accidentally to cause this.
> > >>
> > >> Sounds like arch/arm/mach-omap2/Makefile change needs to be removed
> > >> to always still build in timer.o. And probably timer.c needs back
> > >> the ifdef for CONFIG_SOC_HAS_REALTIME_COUNTER.
> > >>
> > >> I'll take a look today.
> > >
> > > I've sent a patch along those lines as:
> > >
> > > [PATCH] ARM: OMAP2+: Fix regression for using local timer on non-SMP SoCs
> > >
> > > A link for the patch at [0] below.
> > >
> > CPU local timers not being in always ON power domain use to be the
> > reason on early version of the SOCs but later SOC moved the CPU local
> > timer also in always on domain. Probably AM43xx does loose local timer
> > on CPU PD in low power so yes broadcast would be needed with dmtimer
> > help.
> >
> > >
> > > [0] https://lore.kernel.org/linux-omap/20200528155453.8585-1-tony@atomide.com/T/#u
> > >
> > This should restore it.
> 
> Should I apply the fix directly to the arm/soc branch that has the
> other changes then?

Sure please do, that saves a single-fix pull request.

Regards,

Tony