From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: [PATCH] hwmon: (gpio-fan) Allow usage of gpio operations that may sleep Date: Thu, 4 Dec 2014 11:05:28 -0800 Message-ID: <20141204190528.GA16925@roeck-us.net> References: <1417712328-29831-1-git-send-email-nm@ti.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1417712328-29831-1-git-send-email-nm@ti.com> Sender: linux-kernel-owner@vger.kernel.org To: Nishanth Menon Cc: Jean Delvare , linux-kernel@vger.kernel.org, lm-sensors@lm-sensors.org, linux-omap@vger.kernel.org List-Id: linux-omap@vger.kernel.org On Thu, Dec 04, 2014 at 10:58:47AM -0600, Nishanth Menon wrote: > Certain I2C based GPIO expanders could be used in sleepable context, > this results in: > [ 115.890569] ------------[ cut here ]------------ > [ 115.895422] WARNING: CPU: 0 PID: 1115 at drivers/gpio/gpiolib.c:1370 gpiod_set_raw_value+0x40/0x4c() > [ 115.905024] Modules linked in: > [ 115.908229] CPU: 0 PID: 1115 Comm: sh Tainted: G W 3.18.0-rc7-next-20141203-dirty #1 > [ 115.917461] Hardware name: Generic DRA74X (Flattened Device Tree) > [ 115.923876] [] (unwind_backtrace) from [] (show_stack+0x10/0x14) > [ 115.932013] [] (show_stack) from [] (dump_stack+0x78/0x94) > [ 115.939594] [] (dump_stack) from [] (warn_slowpath_common+0x7c/0xb4) > [ 115.948094] [] (warn_slowpath_common) from [] (warn_slowpath_null+0x1c/0x24) > [ 115.957315] [] (warn_slowpath_null) from [] (gpiod_set_raw_value+0x40/0x4c) > [ 115.966457] [] (gpiod_set_raw_value) from [] (set_fan_speed+0x4c/0x64) > [ 115.975145] [] (set_fan_speed) from [] (set_rpm+0x98/0xac) > [ 115.982742] [] (set_rpm) from [] (dev_attr_store+0x18/0x24) > [ 115.990426] [] (dev_attr_store) from [] (sysfs_kf_write+0x4c/0x50) > [ 115.998742] [] (sysfs_kf_write) from [] (kernfs_fop_write+0xbc/0x19c) > [ 116.007333] [] (kernfs_fop_write) from [] (vfs_write+0xb0/0x1a0) > [ 116.015461] [] (vfs_write) from [] (SyS_write+0x44/0x84) > [ 116.022881] [] (SyS_write) from [] (ret_fast_syscall+0x0/0x48) > [ 116.030833] ---[ end trace 3a0b636123acab82 ]--- > > So, switch over to sleepable GPIO operations as there is no mandatory > need for non-sleepable gpio operations in the fan driver. > > This allows the fan driver to be used with i2c based gpio expanders such > as palmas_gpio. > > Signed-off-by: Nishanth Menon Applied to hwmon-next. Do we need this in older kernels ? Thanks, Guenter