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([2a02:810d:15c0:828:5050:151b:e755:1c6]) by smtp.gmail.com with ESMTPSA id s26-20020a170906169a00b009200601ea12sm7224670ejd.208.2023.03.22.07.53.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 22 Mar 2023 07:53:23 -0700 (PDT) Message-ID: <7b939818-993a-e849-e7e0-ae9ea74ea52b@linaro.org> Date: Wed, 22 Mar 2023 15:53:21 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH V1 3/4] soc: qcom: boot_stat: Add Driver Support for Boot Stats Content-Language: en-US To: Souradeep Chowdhury , Andy Gross , Konrad Dybcio , Krzysztof Kozlowski , Bjorn Andersson , Rob Herring Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, Sibi Sankar , Rajendra Nayak References: <3f385562845ae26d519940ca8098fde89282991b.1679403696.git.quic_schowdhu@quicinc.com> <611ea918-64a6-f306-b5ec-db55e41abda2@linaro.org> <321005fc-1bfd-c04d-b2b5-d85d213ac00a@quicinc.com> From: Krzysztof Kozlowski In-Reply-To: <321005fc-1bfd-c04d-b2b5-d85d213ac00a@quicinc.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/03/2023 14:54, Souradeep Chowdhury wrote: > > > On 3/21/2023 11:07 PM, Krzysztof Kozlowski wrote: >> On 21/03/2023 14:51, Souradeep Chowdhury wrote: >>> All of Qualcomm's proprietary Android boot-loaders capture boot time >>> stats, like the time when the bootloader started execution and at what >>> point the bootloader handed over control to the kernel etc. in the IMEM >>> region. This information is captured in a specific format by this driver >>> by mapping a structure to the IMEM memory region and then accessing the >>> members of the structure to print the information. This information is >>> useful in verifying if the existing boot KPIs have regre >> >> >>> +/** >>> + * struct boot_stats - timestamp information related to boot stats >>> + * @bootloader_start: Time for the starting point of the abl bootloader >>> + * @bootloader_end: Time when the kernel starts loading from abl bootloader >>> + */ >>> +struct boot_stats { >>> + u32 bootloader_start; >>> + u32 bootloader_end; >>> +} __packed; >>> + >>> +static struct boot_stats __iomem *boot_stats; >>> +static void __iomem *mpm_counter_base; >>> +static u32 mpm_counter_freq; >> >> No file-scope variables. Does not scale, not easy for review and >> maintenance. Avoid such code. > > Ack >> >>> + >>> +static int mpm_parse_dt(void) >>> +{ >>> + struct device_node *np_imem, *np_mpm2; >>> + >>> + np_imem = of_find_compatible_node(NULL, NULL, >>> + "qcom,imem-boot_stats"); >>> + if (!np_imem) { >>> + pr_err("can't find qcom,imem node\n"); >> >> So you are printing errors everywhere, on every soc and with compile >> test on every platform there is in the world... sorry, it does not work >> like that. > > Ack >> >>> + return -ENODEV; >>> + } >>> + boot_stats = of_iomap(np_imem, 0); >>> + if (!boot_stats) { >>> + pr_err("boot_stats: Can't map imem\n"); >>> + goto err1; >>> + } >> >> >>> + >>> +static void __exit boot_stats_exit(void) >>> +{ >>> +} >>> +module_exit(boot_stats_exit) >> >> >> I don't think this is some special code which deserves init calls. Make >> it module_platform_driver(). > > Since this just reads some values from the Imem region and prints it to > the user and doesn't have a specific device associated with it, a Which is not really an argument for such antipattern, but okay... > generic module code is written for it and not a module_platform_driver(). ... so how do you handle deferred probe? Best regards, Krzysztof