From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Horman Date: Wed, 17 Jun 2015 08:42:04 +0000 Subject: Re: possible regression caused by "clocksource: sh_tmu: Set cpu_possible_mask to fix SMP broadcast" Message-Id: <20150617084203.GB9458@verge.net.au> List-Id: References: <20150617024833.GE5143@verge.net.au> In-Reply-To: <20150617024833.GE5143@verge.net.au> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-sh@vger.kernel.org On Wed, Jun 17, 2015 at 04:51:07PM +0900, Magnus Damm wrote: > Hi Geert, > > On Wed, Jun 17, 2015 at 4:45 PM, Geert Uytterhoeven > wrote: > > On Wed, Jun 17, 2015 at 8:52 AM, Magnus Damm wrote: > >> On Wed, Jun 17, 2015 at 11:48 AM, Simon Horman wrote: > >>> I have observed what appears to be a regression caused by > >>> f2a5473861cf ("clocksource: sh_tmu: Set cpu_possible_mask to fix SMP > >>> broadcast"), which was included in v3.19. > >>> > >>> The problem I see is that with a kernel compiled using marzen_defconfig on > >>> the r8a7779/marzen board: i.e. a "legacy" kernel. > >>> > >>> The problem does not manifest when booting the same board using > >>> a kernel built with shmobile_defconfig: i.e. a multiplatform kernel. > >>> > >>> It does not appear to affect other boards I have access to: > >>> emev2/kzm9d, r7s72100/genmai, r8a73a4/ape6evm, r8a7740/armadillo900eva, > >>> r8a77798/bockw r8a7790/lager r8a7791/koelsch, r8a7794/alt, sh73a0/kzm9g. > >>> > >>> I have observed this problem on the renesas-devel-20150617-v4.1-rc8 > >>> tag of my renesas tree. But I do not believe it is exclusive to that tag. > >>> > >>> The problem appears to be that there is no clocksource available during > >>> early boot. The boot log at the end of the email was obtained by > >>> enabling DEBUG_LL and earlyprintk. > >> > >> Thanks for reporting this. I suspect that the reason why this triggers > >> on legacy is that we i such case most likely don't have TWD together > >> with CCF. Since this is just old legacy code and the multiplatform > > > > We do have other A9 SMP SoCs (sh73a0, r8a7778). > > > > r8a7779.dtsi has an "arm,cortex-a9-twd-timer" node. r8a7778 hasn't. > > Right, r8a7778 is not SMP so I don't think there is any TWD there. Or > at least the Linux driver did not use to support running in UP mode. > > > sh73a0 also has it, but see http://www.spinics.net/lists/linux-sh/msg39128.html > > As bockw and marzen still have -reference variants, it may be more > > difficult to fix. > > Your TWD DT node is nicely pointing out the clock via CCF. On legacy > this is most likely not possible, so we end up with trying to > automatically determining the clock by assuming another clock is > running. At least it used to be like that. > > >> version should be equivalent I suggest that the correct approach is to > >> use multiplatform support instead of legacy. And legacy r8a7779 > >> support should be removed right away if it hasn't already. > > > > Please wait, so I don't have to rebase the sh73a0/r8a7740 patches I'm > > about to send out ;-) > > Sure, please push out so we can clean up. =) I'm happy to proceed with an orderly removal of marzen legacy as a resolution to this problem.