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[80.251.214.228]) by smtp.gmail.com with ESMTPSA id ik7-20020a170902ab0700b0016f8e8032c4sm11167699plb.129.2022.10.12.18.31.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 12 Oct 2022 18:31:28 -0700 (PDT) Date: Thu, 13 Oct 2022 09:31:21 +0800 From: Shawn Guo To: Greg Kroah-Hartman Cc: Jiri Slaby , Martin Kaiser , Pengutronix Kernel Team , NXP Linux Team , linux-serial@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] serial: imx: Add missing .thaw_noirq hook Message-ID: <20221013013121.GA2354004@dragon> References: <20221012121353.2346280-1-shawn.guo@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org On Wed, Oct 12, 2022 at 06:20:35PM +0200, Greg Kroah-Hartman wrote: > On Wed, Oct 12, 2022 at 08:13:53PM +0800, Shawn Guo wrote: > > The following warning is seen with non-console UART instance when > > system hibernates. > > > > [ 37.371969] ------------[ cut here ]------------ > > [ 37.376599] uart3_root_clk already disabled > > [ 37.380810] WARNING: CPU: 0 PID: 296 at drivers/clk/clk.c:952 clk_core_disable+0xa4/0xb0 > > ... > > [ 37.506986] Call trace: > > [ 37.509432] clk_core_disable+0xa4/0xb0 > > [ 37.513270] clk_disable+0x34/0x50 > > [ 37.516672] imx_uart_thaw+0x38/0x5c > > [ 37.520250] platform_pm_thaw+0x30/0x6c > > [ 37.524089] dpm_run_callback.constprop.0+0x3c/0xd4 > > [ 37.528972] device_resume+0x7c/0x160 > > [ 37.532633] dpm_resume+0xe8/0x230 > > [ 37.536036] hibernation_snapshot+0x288/0x430 > > [ 37.540397] hibernate+0x10c/0x2e0 > > [ 37.543798] state_store+0xc4/0xd0 > > [ 37.547203] kobj_attr_store+0x1c/0x30 > > [ 37.550953] sysfs_kf_write+0x48/0x60 > > [ 37.554619] kernfs_fop_write_iter+0x118/0x1ac > > [ 37.559063] new_sync_write+0xe8/0x184 > > [ 37.562812] vfs_write+0x230/0x290 > > [ 37.566214] ksys_write+0x68/0xf4 > > [ 37.569529] __arm64_sys_write+0x20/0x2c > > [ 37.573452] invoke_syscall.constprop.0+0x50/0xf0 > > [ 37.578156] do_el0_svc+0x11c/0x150 > > [ 37.581648] el0_svc+0x30/0x140 > > [ 37.584792] el0t_64_sync_handler+0xe8/0xf0 > > [ 37.588976] el0t_64_sync+0x1a0/0x1a4 > > [ 37.592639] ---[ end trace 56e22eec54676d75 ]--- > > > > On hibernating, pm core calls into related hooks in sequence like: > > > > .freeze > > .freeze_noirq > > .thaw_noirq > > .thaw > > > > With .thaw_noirq hook being absent, the clock will be disabled in a > > unbalanced call which results the warning above. > > > > imx_uart_freeze() > > clk_prepare_enable() > > imx_uart_suspend_noirq() > > clk_disable() > > imx_uart_thaw > > clk_disable_unprepare() > > > > Adding the missing .thaw_noirq hook as imx_uart_resume_noirq() will have > > the call sequence corrected as below and thus fix the warning. > > > > imx_uart_freeze() > > clk_prepare_enable() > > imx_uart_suspend_noirq() > > clk_disable() > > imx_uart_resume_noirq() > > clk_enable() > > imx_uart_thaw > > clk_disable_unprepare() > > > > Signed-off-by: Shawn Guo > > What commit id does this fix, and does it need to go to older/stable > kernels? The .thaw_noirq was missing from commit 94be6d74d040 ("serial: imx: add hibernation support"), but it did not cause the warning until commit 09df0b3464e5 ("serial: imx: fix endless loop during suspend") changes clock calls. So I should have added: Fixes: 09df0b3464e5 ("serial: imx: fix endless loop during suspend") Shawn