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[79.139.233.37]) by smtp.googlemail.com with ESMTPSA id t1sm4901890lji.98.2019.12.13.07.15.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Dec 2019 07:15:13 -0800 (PST) Subject: Re: [PATCH v1 1/3] i2c: tegra: Support atomic transfers To: Thierry Reding Cc: Jonathan Hunter , Laxman Dewangan , Wolfram Sang , linux-i2c@vger.kernel.org, linux-tegra@vger.kernel.org, linux-kernel@vger.kernel.org References: <20191212233428.14648-1-digetx@gmail.com> <20191212233428.14648-2-digetx@gmail.com> <20191213151208.GC222809@ulmo> From: Dmitry Osipenko Message-ID: <5a2a9cef-f4ed-c5a4-1f35-c89c3b5106a6@gmail.com> Date: Fri, 13 Dec 2019 18:15:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20191213151208.GC222809@ulmo> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 13.12.2019 18:12, Thierry Reding пишет: > On Fri, Dec 13, 2019 at 02:34:26AM +0300, Dmitry Osipenko wrote: >> System shutdown may happen with interrupts being disabled and in this case >> I2C core rejects transfers if atomic transfer isn't supported by driver. >> >> There were several occurrences where I found my Nexus 7 completely >> discharged despite of being turned off and then one day I spotted this in >> the log: >> >> reboot: Power down >> ------------[ cut here ]------------ >> WARNING: CPU: 0 PID: 1 at drivers/i2c/i2c-core.h:40 i2c_transfer+0x95/0x9c >> No atomic I2C transfer handler for 'i2c-1' >> Modules linked in: tegra30_devfreq >> CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 5.4.0-next-20191202-00120-gf7ecd80fb803-dirty #3195 >> Hardware name: NVIDIA Tegra SoC (Flattened Device Tree) >> [] (unwind_backtrace) from [] (show_stack+0x11/0x14) >> [] (show_stack) from [] (dump_stack+0x85/0x94) >> [] (dump_stack) from [] (__warn+0xc1/0xc4) >> [] (__warn) from [] (warn_slowpath_fmt+0x61/0x78) >> [] (warn_slowpath_fmt) from [] (i2c_transfer+0x95/0x9c) >> [] (i2c_transfer) from [] (regmap_i2c_read+0x4d/0x6c) >> [] (regmap_i2c_read) from [] (_regmap_raw_read+0x99/0x1cc) >> [] (_regmap_raw_read) from [] (_regmap_bus_read+0x23/0x38) >> [] (_regmap_bus_read) from [] (_regmap_read+0x3d/0xfc) >> [] (_regmap_read) from [] (_regmap_update_bits+0x87/0xc4) >> [] (_regmap_update_bits) from [] (regmap_update_bits_base+0x39/0x50) >> [] (regmap_update_bits_base) from [] (max77620_pm_power_off+0x29/0x2c) >> [] (max77620_pm_power_off) from [] (__do_sys_reboot+0xe9/0x170) >> [] (__do_sys_reboot) from [] (ret_fast_syscall+0x1/0x28) >> Exception stack(0xde907fa8 to 0xde907ff0) >> 7fa0: 00000000 00000000 fee1dead 28121969 4321fedc 00000000 >> 7fc0: 00000000 00000000 00000000 00000058 00000000 00000000 00000000 00000000 >> 7fe0: 0045adf0 bed9abb8 004444a0 b6c666d0 >> ---[ end trace bdd18f87595b1a5e ]--- >> >> The atomic transferring is implemented by enforcing PIO mode for the >> transfer and by polling interrupt status until transfer is completed or >> failed. >> >> Now system shuts down properly every time. >> >> Signed-off-by: Dmitry Osipenko >> --- >> drivers/i2c/busses/i2c-tegra.c | 95 +++++++++++++++++++++++++++++++--- >> 1 file changed, 88 insertions(+), 7 deletions(-) > > I ran this on the test farm and the results are all green, so: > > Tested-by: Thierry Reding > Thanks! Does the farm test board's shut down by verifying the hardware's power state?