Re: [PATCH 3/7] eeprom: at24: extend driver to plug into the NVMEM framework

From: Andrew Lunn <andrew@lunn.ch>
To: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: GregKH <greg@kroah.com>,
	Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
	Maxime Ripard <maxime.ripard@free-electrons.com>,
	Wolfram Sang <wsa@the-dreams.de>,
	broonie@kernel.org, vz@mleia.com, fd@ti.com,
	LKML <linux-kernel@vger.kernel.org>,
	Pantelis Antoniou <pantelis.antoniou@konsulko.com>
Subject: Re: [PATCH 3/7] eeprom: at24: extend driver to plug into the NVMEM framework
Date: Fri, 12 Feb 2016 10:16:12 +0100	[thread overview]
Message-ID: <20160212091612.GB9276@lunn.ch> (raw)
In-Reply-To: <CAMpxmJX1nFMmKroxMLWPyTAzkKB50bZnE4Pu=0ch1CfR7FhNXw@mail.gmail.com>

On Fri, Jan 29, 2016 at 02:10:17PM +0100, Bartosz Golaszewski wrote:
> Hi Andrew,
> 
> the patch works, but I'm hitting the following BUG when instantiating
> an at24c32 device:

Hi Bortosz

Sorry for taking so long to get back to you. Can you confirm you had
lockdep turned on.

Thanks
	Andrew

> 
> # echo 24c32 0x54 > /sys/class/i2c-adapter/i2c-2/new_device
> [    3.741893] BUG: key de753e8c not in .data!
> [    3.749166] ------------[ cut here ]------------
> [    3.756649] WARNING: CPU: 0 PID: 102 at
> kernel/locking/lockdep.c:3002 __kernfs_create_file+0x60/0xc4()
> [    3.769048] DEBUG_LOCKS_WARN_ON(1)
> [    3.772463] Modules linked in: at24(+) nvmem_core cpufreq_dt
> omap_wdt thermal_sys leds_gpio led_class hwmon
> [    3.788301] CPU: 0 PID: 102 Comm: udevd Not tainted 4.5.0-rc1-acme+ #7
> [    3.797833] Hardware name: Generic AM33XX (Flattened Device Tree)
> [    3.806920] [<c0017d44>] (unwind_backtrace) from [<c0014034>]
> (show_stack+0x10/0x14)
> [    3.817762] [<c0014034>] (show_stack) from [<c036b478>]
> (dump_stack+0x84/0x9c)
> [    3.828071] [<c036b478>] (dump_stack) from [<c003c850>]
> (warn_slowpath_common+0x7c/0xb8)
> [    3.839284] [<c003c850>] (warn_slowpath_common) from [<c003c8bc>]
> (warn_slowpath_fmt+0x30/0x40)
> [    3.851154] [<c003c8bc>] (warn_slowpath_fmt) from [<c01fbf3c>]
> (__kernfs_create_file+0x60/0xc4)
> [    3.863025] [<c01fbf3c>] (__kernfs_create_file) from [<c01fc794>]
> (sysfs_add_file_mode_ns+0x98/0x1bc)
> [    3.875488] [<c01fc794>] (sysfs_add_file_mode_ns) from [<c01fca40>]
> (sysfs_create_bin_file+0x38/0x44)
> [    3.888000] [<c01fca40>] (sysfs_create_bin_file) from [<bf033770>]
> (nvmem_register+0x2cc/0x34c [nvmem_core])
> [    3.901190] [<bf033770>] (nvmem_register [nvmem_core]) from
> [<bf03c958>] (at24_probe+0x430/0x59c [at24])
> [    3.914055] [<bf03c958>] (at24_probe [at24]) from [<c054be80>]
> (i2c_device_probe+0x168/0x1fc)
> [    3.925926] [<c054be80>] (i2c_device_probe) from [<c045ba44>]
> (driver_probe_device+0x208/0x2c0)
> [    3.938003] [<c045ba44>] (driver_probe_device) from [<c045bb90>]
> (__driver_attach+0x94/0x98)
> [    3.949821] [<c045bb90>] (__driver_attach) from [<c0459d80>]
> (bus_for_each_dev+0x6c/0xa0)
> [    3.961373] [<c0459d80>] (bus_for_each_dev) from [<c045b038>]
> (bus_add_driver+0x18c/0x214)
> [    3.973037] [<c045b038>] (bus_add_driver) from [<c045c4f4>]
> (driver_register+0x78/0xf8)
> [    3.984458] [<c045c4f4>] (driver_register) from [<c054ca00>]
> (i2c_register_driver+0x2c/0x80)
> [    3.996349] [<c054ca00>] (i2c_register_driver) from [<c0009804>]
> (do_one_initcall+0x80/0x1e0)
> [    4.008344] [<c0009804>] (do_one_initcall) from [<c0123110>]
> (do_init_module+0x5c/0x1d4)
> [    4.019910] [<c0123110>] (do_init_module) from [<c00cb2e4>]
> (load_module+0x1cc0/0x1f48)
> [    4.031378] [<c00cb2e4>] (load_module) from [<c00cb71c>]
> (SyS_finit_module+0x64/0x74)
> [    4.042665] [<c00cb71c>] (SyS_finit_module) from [<c000f820>]
> (ret_fast_syscall+0x0/0x1c)
> [    4.054322] ---[ end trace 692db3ff57b96549 ]---
> [    4.062228] at24 2-0054: 4096 byte 24c32 EEPROM, writable, 1 bytes/write
> [    4.073224] i2c i2c-2: new_device: Instantiated device 24c32 at 0x54
> 
> It seems to result in the nvmem attribute having 0 size while the
> legacy eeprom file has size corresponding with the chip's memory area
> size in bytes.
> 
> Best regards,
> Bartosz Golaszewski