From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Wed, 18 May 2011 09:47:33 +0100 Subject: [PATCH] ARM: fix mistaken dependency for CPU_HAS_PMU In-Reply-To: <1305686080-13182-1-git-send-email-tom.leiming@gmail.com> References: <1305686080-13182-1-git-send-email-tom.leiming@gmail.com> Message-ID: <000001cc1538$3ae8a9e0$b0b9fda0$@deacon@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi, > From: Ming Lei > > Obviously it is mistake for CPU_HAS_PMU to depend on > (!ARCH_OMAP3 || OMAP3_EMU). It's not that obvious! > No mattery it is omap3 or not, we can build pmu.o into > kernel safely. In fact, arm-v7 of omap3 has pmu inside > also. Yes, but the PMU on Omap3 doesn't work unless you enable the emu clk, which is done in kernel/etm.c. Rather than duplicate that code (which only seems to be needed for Omap anyway) I decided to add a dependency on OMAP3_EMU so the clock gets enabled in etb_probe. > So fix it that we can build pmu into kernel to support perf > for some valid config(such as enable both omap4 and omap3, > but OMAP3_EMU). No, I don't like this. The reason I don't like it is because it will lead to lots of bug reports that perf doesn't work on Omap3 because they haven't got the emu clock ticking. It was this scenario that led to the dependency being introduced in the first place: 8954bb0d ("OMAP3: pmu: make CPU_HAS_PMU dependent on OMAP3_EMU") Is there a problem building the etm support for Omap4? Will