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Fri, 29 Jul 2022 11:45:26 -0700 (PDT) Message-ID: <7d9607ed-f8eb-f3a2-22e4-4d2a240919c9@gmail.com> Date: Fri, 29 Jul 2022 11:45:10 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH] firmware/psci: Add debugfs support to ease debugging Content-Language: en-US To: Dmitry Baryshkov , Sudeep Holla Cc: Mark Rutland , Lorenzo Pieralisi , linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, linux-arm-msm@vger.kernel.org References: <20220727200901.1142557-1-dmitry.baryshkov@linaro.org> <20220728090806.nnighsbx2lcgugon@bogus> From: Florian Fainelli In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220729_114530_230576_6CA6D5B2 X-CRM114-Status: GOOD ( 21.24 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 7/28/22 02:20, Dmitry Baryshkov wrote: > On Thu, 28 Jul 2022 at 12:08, Sudeep Holla wrote: >> >> On Wed, Jul 27, 2022 at 11:09:01PM +0300, Dmitry Baryshkov wrote: >>> To ease debugging of PSCI supported features, add debugfs file called >>> 'psci' describing PSCI and SMC CC versions >> >> These 2 are for sure in the boot log. Having them is debugfs accessible >> via file system add not much value as we would hit issues quite early in >> the boot for most of the things related to PSCI. > > Yes, it was just to have all the information in a single place. > >>> enabled features and options. >>> >> >> We have psci_checker.c which does some minimal testing of PSCI. I prefer >> to add things to that rather than a debugfs as it is run during boot. IMO >> it is usual useful to debug things that cause boot issue most of the time. >> I am not against this so I will leave it to the maintainers. > > In my case I was not debugging the boot issues (which of course would > have required a different approach), but I was trying to understand > runtime capabilities, thus debugfs fits pretty well. > > Another point for the debugfs entry: most of the people run the kernel > with the psci_checker being turned off, but with debugfs being > enabled. If we are trying to narrow down firmware capabilities of the > random device, it is much easier to ask them to cat the dbeugfs file > rather than to rebuild the kernel. > Yes I would agree with both of those points, in fact, I would go one step further and add the ability to probe an arbitrary PSCI function ID, since deployed firmware typically go beyond the standard PSCI scope and implement a variety of custom extensions (at least we do). Thanks! -- Florian _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel