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Subject[PATCH v2] drivers: cpufreq: Fix sysfs duplicate filename creation for platform-device
Date
From: Suniel Mahesh <sunil.m@techveda.org>

ti-cpufreq and cpufreq-dt-platdev drivers are registering platform-device
with same name "cpufreq-dt" using platform_device_register_*() routines.
This is leading to build warnings appended below.

Providing hardware information to OPP framework along with the platform-
device creation should be done by ti-cpufreq driver before cpufreq-dt
driver comes into place.

This patch add's TI SoC am33xx (uses opp-v2 property) in the blacklist of
devices in cpufreq-dt-platform driver to avoid creating platform-device
twice and remove build warnings (suggested by Viresh Kumar).

[ 2.370167] ------------[ cut here ]------------
[ 2.375087] WARNING: CPU: 0 PID: 1 at fs/sysfs/dir.c:31 sysfs_warn_dup+0x58/0x78
[ 2.383112] sysfs: cannot create duplicate filename '/devices/platform/cpufreq-dt'
[ 2.391219] Modules linked in:
[ 2.394506] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.13.0-next-20170912 #1
[ 2.402006] Hardware name: Generic AM33XX (Flattened Device Tree)
[ 2.408437] [<c0110a28>] (unwind_backtrace) from [<c010ca84>] (show_stack+0x10/0x14)
[ 2.416568] [<c010ca84>] (show_stack) from [<c0827d64>] (dump_stack+0xac/0xe0)
[ 2.424165] [<c0827d64>] (dump_stack) from [<c0137470>] (__warn+0xd8/0x104)
[ 2.431488] [<c0137470>] (__warn) from [<c01374d0>] (warn_slowpath_fmt+0x34/0x44)
[ 2.439351] [<c01374d0>] (warn_slowpath_fmt) from [<c03459d0>] (sysfs_warn_dup+0x58/0x78)
[ 2.447938] [<c03459d0>] (sysfs_warn_dup) from [<c0345ab8>] (sysfs_create_dir_ns+0x80/0x98)
[ 2.456719] [<c0345ab8>] (sysfs_create_dir_ns) from [<c082c554>] (kobject_add_internal+0x9c/0x2d4)
[ 2.466124] [<c082c554>] (kobject_add_internal) from [<c082c7d8>] (kobject_add+0x4c/0x9c)
[ 2.474712] [<c082c7d8>] (kobject_add) from [<c05803e4>] (device_add+0xcc/0x57c)
[ 2.482489] [<c05803e4>] (device_add) from [<c0584b74>] (platform_device_add+0x100/0x220)
[ 2.491085] [<c0584b74>] (platform_device_add) from [<c05855a8>] (platform_device_register_full+0xf4/0x118)
[ 2.501305] [<c05855a8>] (platform_device_register_full) from [<c067023c>] (ti_cpufreq_init+0x150/0x22c)
[ 2.511253] [<c067023c>] (ti_cpufreq_init) from [<c0101df4>] (do_one_initcall+0x3c/0x170)
[ 2.519838] [<c0101df4>] (do_one_initcall) from [<c0c00eb4>] (kernel_init_freeable+0x1fc/0x2c4)
[ 2.528974] [<c0c00eb4>] (kernel_init_freeable) from [<c083bcac>] (kernel_init+0x8/0x110)
[ 2.537565] [<c083bcac>] (kernel_init) from [<c0107d18>] (ret_from_fork+0x14/0x3c)
[ 2.545981] ---[ end trace 2fc00e213c13ab20 ]---
[ 2.551051] ------------[ cut here ]------------
[ 2.555931] WARNING: CPU: 0 PID: 1 at lib/kobject.c:240 kobject_add_internal+0x254/0x2d4
[ 2.564578] kobject_add_internal failed for cpufreq-dt with -EEXIST, don't try to register
things with the same name in the same directory.
[ 2.577977] Modules linked in:
[ 2.581261] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 4.13.0-next-20170912 #1
[ 2.590013] Hardware name: Generic AM33XX (Flattened Device Tree)
[ 2.596437] [<c0110a28>] (unwind_backtrace) from [<c010ca84>] (show_stack+0x10/0x14)
[ 2.604573] [<c010ca84>] (show_stack) from [<c0827d64>] (dump_stack+0xac/0xe0)
[ 2.612172] [<c0827d64>] (dump_stack) from [<c0137470>] (__warn+0xd8/0x104)
[ 2.619494] [<c0137470>] (__warn) from [<c01374d0>] (warn_slowpath_fmt+0x34/0x44)
[ 2.627362] [<c01374d0>] (warn_slowpath_fmt) from [<c082c70c>] (kobject_add_internal+0x254/0x2d4)
[ 2.636666] [<c082c70c>] (kobject_add_internal) from [<c082c7d8>] (kobject_add+0x4c/0x9c)
[ 2.645255] [<c082c7d8>] (kobject_add) from [<c05803e4>] (device_add+0xcc/0x57c)
[ 2.653027] [<c05803e4>] (device_add) from [<c0584b74>] (platform_device_add+0x100/0x220)
[ 2.661615] [<c0584b74>] (platform_device_add) from [<c05855a8>] (platform_device_register_full+0xf4/0x118)
[ 2.671833] [<c05855a8>] (platform_device_register_full) from [<c067023c>] (ti_cpufreq_init+0x150/0x22c)
[ 2.681779] [<c067023c>] (ti_cpufreq_init) from [<c0101df4>] (do_one_initcall+0x3c/0x170)
[ 2.690377] [<c0101df4>] (do_one_initcall) from [<c0c00eb4>] (kernel_init_freeable+0x1fc/0x2c4)
[ 2.699510] [<c0c00eb4>] (kernel_init_freeable) from [<c083bcac>] (kernel_init+0x8/0x110)
[ 2.708106] [<c083bcac>] (kernel_init) from [<c0107d18>] (ret_from_fork+0x14/0x3c)
[ 2.716217] ---[ end trace 2fc00e213c13ab21 ]---

Fixes: edeec420de24 ("cpufreq: dt-cpufreq: platdev Automatically create device with OPP v2")
Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
---
Changes for v2:
- The approach (as a result patch decsription) was changed as per
inputs given by Viresh.
- Patch was compile tested and built(ARCH=arm) on next-20170918.
---
Note:
- Patch was hardware tested on AM335x SOC based board.
- cpufreq-dt driver got probed and entries related to Dynamic Voltage
and Frequency scaling were created in
sysfs @ sys/devices/system/cpu/cpu0/cpufreq.
- No build/run-time issues reported.
---
drivers/cpufreq/cpufreq-dt-platdev.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/drivers/cpufreq/cpufreq-dt-platdev.c b/drivers/cpufreq/cpufreq-dt-platdev.c
index a020da7..61fe7ee 100644
--- a/drivers/cpufreq/cpufreq-dt-platdev.c
+++ b/drivers/cpufreq/cpufreq-dt-platdev.c
@@ -106,6 +106,7 @@
* platforms using "operating-points-v2" property.
*/
static const struct of_device_id blacklist[] __initconst = {
+ { .compatible = "ti,am33xx", },
{ }
};

--
1.9.1
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