From mboxrd@z Thu Jan 1 00:00:00 1970 From: will.deacon@arm.com (Will Deacon) Date: Fri, 27 Apr 2018 15:37:20 +0100 Subject: [PATCH v4 2/2] ThunderX2: Add Cavium ThunderX2 SoC UNCORE PMU driver In-Reply-To: <20180427081525.f9dcc756678baf3bb6e6e473@arm.com> References: <20180425090047.6485-1-ganapatrao.kulkarni@cavium.com> <20180425090047.6485-3-ganapatrao.kulkarni@cavium.com> <20180426170624.bfcba885431d57d0de2a3ddd@arm.com> <20180427093027.ngtuoezyh6mtz26p@lakrids.cambridge.arm.com> <20180427081525.f9dcc756678baf3bb6e6e473@arm.com> Message-ID: <20180427143719.GA5093@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Apr 27, 2018 at 08:15:25AM -0500, Kim Phillips wrote: > On Fri, 27 Apr 2018 10:30:27 +0100 > Mark Rutland wrote: > > On Thu, Apr 26, 2018 at 05:06:24PM -0500, Kim Phillips wrote: > > > On Wed, 25 Apr 2018 14:30:47 +0530 > > > Ganapatrao Kulkarni wrote: > > > > > > > +static int thunderx2_uncore_event_init(struct perf_event *event) > > > > > This PMU driver can be made more user-friendly by not just silently > > > returning an error code such as -EINVAL, but by emitting a useful > > > message describing the specific error via dmesg. > > > > As has previously been discussed on several occasions, patches which log > > to dmesg in a pmu::event_init() path at any level above pr_debug() are > > not acceptable -- dmesg is not intended as a mechanism to inform users > > of driver-specific constraints. > > I disagree - drivers do it all the time, using dev_err(), dev_warn(), etc. > > > I would appreciate if in future you could qualify your suggestion with > > the requirement that pr_debug() is used. > > It shouldn't - the driver isn't being debugged, it's in regular use. For anything under drivers/perf/, I'd prefer not to have these prints and instead see efforts to improve error reporting via the perf system call interface. Anyway, I think this driver has bigger problems that need addressing. Will