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AJvYcCV+TqiKe+RweYOUw0OmVvMDb3OFWd5DGtMzprdEOsNbKQPPYQKzkAlc5MZ/GYYhl5Fk2MWAkCZEhH83IBtuOPdxK/8UtRT9Ef6NWQ== X-Gm-Message-State: AOJu0Ywqv28xSqiLb4M+AHarGAeWRCfnJRCoj72QWmW81FyRChWSQySF MVJWWDdkU+OyNqp+iDr77FIffBplwnb3J61u3x8r+PyBgCftAdFJiHoskzTSs24= X-Google-Smtp-Source: AGHT+IE/C0L+29QYZm0cbbUKjIoMbxv529O5ACPPWiOR4dDxxX8aZYQdv6fXmf0X8Hy7WdajhXYuLg== X-Received: by 2002:a05:600c:4f0d:b0:41a:14f9:dcee with SMTP id l13-20020a05600c4f0d00b0041a14f9dceemr1659996wmq.21.1713957271320; Wed, 24 Apr 2024 04:14:31 -0700 (PDT) Received: from [192.168.50.4] ([82.78.167.53]) by smtp.gmail.com with ESMTPSA id o12-20020a05600c4fcc00b00418a6d62ad0sm27290070wmq.34.2024.04.24.04.14.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 24 Apr 2024 04:14:30 -0700 (PDT) Message-ID: <2d674a18-006f-4182-bc85-bcfa50615495@tuxon.dev> Date: Wed, 24 Apr 2024 14:14:29 +0300 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RESEND v8 09/10] watchdog: rzg2l_wdt: Power on the PM domain in rzg2l_wdt_restart() Content-Language: en-US From: claudiu beznea To: Ulf Hansson Cc: wim@linux-watchdog.org, linux@roeck-us.net, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, p.zabel@pengutronix.de, geert+renesas@glider.be, magnus.damm@gmail.com, biju.das.jz@bp.renesas.com, linux-watchdog@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Claudiu Beznea References: <20240410134044.2138310-1-claudiu.beznea.uj@bp.renesas.com> <20240410134044.2138310-10-claudiu.beznea.uj@bp.renesas.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, Ulf, On 12.04.2024 17:02, claudiu beznea wrote: > Hi, Ulf, > > On 12.04.2024 14:14, Ulf Hansson wrote: >> On Wed, 10 Apr 2024 at 16:19, Claudiu wrote: >>> >>> From: Claudiu Beznea >>> >>> The rzg2l_wdt_restart() is called from atomic context. Calling >>> pm_runtime_{get_sync, resume_and_get}() or any other runtime PM resume >>> APIs is not an option as it may lead to issues as described in commit >>> e4cf89596c1f ("watchdog: rzg2l_wdt: Fix 'BUG: Invalid wait context'") >>> that removed the pm_runtime_get_sync() and used directly the >>> clk_prepare_enable() APIs. >>> >>> Starting with RZ/G3S the watchdog could be part of its own software >>> controlled power domain (see the initial implementation in Link section). >>> In case the watchdog is not used the power domain is off and accessing >>> watchdog registers leads to aborts. >>> >>> To solve this the patch powers on the power domain using >>> dev_pm_genpd_resume() API before enabling its clock. This is not >>> sleeping or taking any other locks as the power domain will not be >>> registered with GENPD_FLAG_IRQ_SAFE flags. >>> >>> Link: https://lore.kernel.org/all/20240208124300.2740313-1-claudiu.beznea.uj@bp.renesas.com >>> Signed-off-by: Claudiu Beznea >>> --- >>> >>> Changes in v8: >>> - none, this patch is new >>> >>> drivers/watchdog/rzg2l_wdt.c | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/drivers/watchdog/rzg2l_wdt.c b/drivers/watchdog/rzg2l_wdt.c >>> index c8c20cfb97a3..98e5e9914a5d 100644 >>> --- a/drivers/watchdog/rzg2l_wdt.c >>> +++ b/drivers/watchdog/rzg2l_wdt.c >>> @@ -12,6 +12,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -164,6 +165,17 @@ static int rzg2l_wdt_restart(struct watchdog_device *wdev, >>> struct rzg2l_wdt_priv *priv = watchdog_get_drvdata(wdev); >>> int ret; >>> >>> + /* >>> + * The device may be part of a power domain that is currently >>> + * powered off. We need to power it up before accessing registers. >>> + * We don't undo the dev_pm_genpd_resume() as the device need to >>> + * be up for the reboot to happen. Also, as we are in atomic context >>> + * here there is no need to increment PM runtime usage counter >>> + * (to make sure pm_runtime_active() doesn't return wrong code). >>> + */ >>> + if (!pm_runtime_active(wdev->parent)) >>> + dev_pm_genpd_resume(wdev->parent); >>> + >> >> I doubt this is the correct solution, but I may be wrong. Unless this >> is invoked at the syscore stage? > > On my case I see it invoked from kernel_restart(). As of my code reading, With the above explanations, do you consider calling dev_pm_genpd_resume() here is still wrong? Do you have any suggestions I could try? Thank you, Claudiu Beznea > at that point only one CPU is active with IRQs disabled (done in > machine_restart()). Below is the stack trace decoded on next-20240410 with > this series > (https://lore.kernel.org/all/20240410134044.2138310-1-claudiu.beznea.uj@bp.renesas.com/) > on top and the one from here (adding power domain support): > https://lore.kernel.org/all/20240410122657.2051132-1-claudiu.beznea.uj@bp.renesas.com/ > > Hardware name: Renesas SMARC EVK version 2 based on r9a08g045s33 (DT) > Call trace: > dump_backtrace (arch/arm64/kernel/stacktrace.c:319) > show_stack (arch/arm64/kernel/stacktrace.c:326) > dump_stack_lvl (lib/dump_stack.c:117) > dump_stack (lib/dump_stack.c:124) > rzg2l_wdt_restart (drivers/watchdog/rzg2l_wdt.c:180) > watchdog_restart_notifier (drivers/watchdog/watchdog_core.c:188) > atomic_notifier_call_chain (kernel/notifier.c:98 kernel/notifier.c:231) > do_kernel_restart (kernel/reboot.c:236) > machine_restart (arch/arm64/kernel/process.c:145) > kernel_restart (kernel/reboot.c:287) > __do_sys_reboot (kernel/reboot.c:755) > __arm64_sys_reboot (kernel/reboot.c:715) > invoke_syscall (arch/arm64/include/asm/current.h:19 > arch/arm64/kernel/syscall.c:53) > el0_svc_common.constprop.0 (include/linux/thread_info.h:127 > arch/arm64/kernel/syscall.c:141) > do_el0_svc (arch/arm64/kernel/syscall.c:153) > el0_svc (arch/arm64/include/asm/irqflags.h:56 > arch/arm64/include/asm/irqflags.h:77 arch/arm64/kernel/entry-common.c:165 > arch/arm64/kernel/entry-common.c:178 arch/arm64/kernel/entry-common.c:713) > el0t_64_sync_handler (arch/arm64/kernel/entry-common.c:731) > el0t_64_sync (arch/arm64/kernel/entry.S:598) > > The watchdog restart handler is added in restart_handler_list and this list > is invoked though do_kernel_restart(). As of my code investigation the > restart_handler_list is invoked only though do_kernel_restart() and only > though the stack trace above. > > Thank you, > Claudiu Beznea > >> >>> clk_prepare_enable(priv->pclk); >>> clk_prepare_enable(priv->osc_clk); >>> >>> -- >>> 2.39.2 >>> >>> >> >> Can you redirectly me to the complete series, so I can have a better >> overview of the problem? > > This is the series that adds power domain support for RZ/G3S SoC: > https://lore.kernel.org/all/20240410122657.2051132-1-claudiu.beznea.uj@bp.renesas.com/ > > This is the series that adds watchdog support for RZ/G3S SoC: > https://lore.kernel.org/all/20240410134044.2138310-1-claudiu.beznea.uj@bp.renesas.com/ > > Thank you for your review, > Claudiu Beznea > >> >> Kind regards >> Uffe