Quoting Kevin Hilman (2013-02-14 14:50:52)
> Any idea what's going on?
Looks like a couple of different things.
> [ 0.515747] usbhs_omap usbhs_omap: ehci_logic_fck failed:-2
Seems like the clk_get lookup failed here in usbhs_omap_probe. So from
this point on omap->ehci_logic_fck == -ENOENT. This bogus value gets
passed into all of the clk apis, which leads us to the below error.
> [ 0.516021] ------------[ cut here ]------------
> [ 0.516082] WARNING: at /work/kernel/omap/dev/drivers/clk/clk.c:522 __clk_enable+0x8c/0x9c()
> [ 0.516082] Modules linked in:
> [ 0.516143] [<c00145a8>] (unwind_backtrace+0x0/0xf0) from [<c003bd6c>] (warn_slowpath_common+0x4c/0x64)
> [ 0.516143] [<c003bd6c>] (warn_slowpath_common+0x4c/0x64) from [<c003bda0>] (warn_slowpath_null+0x1c/0x24)
> [ 0.516174] [<c003bda0>] (warn_slowpath_null+0x1c/0x24) from [<c0412758>] (__clk_enable+0x8c/0x9c)
> [ 0.516174] [<c0412758>] (__clk_enable+0x8c/0x9c) from [<c0412788>] (clk_enable+0x20/0x3c)
> [ 0.516204] [<c0412788>] (clk_enable+0x20/0x3c) from [<c03317fc>] (usbhs_runtime_resume+0x60/0xa4)
> [ 0.516235] [<c03317fc>] (usbhs_runtime_resume+0x60/0xa4) from [<c031b408>] (pm_generic_runtime_resume+0x2c/0x40)
> [ 0.516265] [<c031b408>] (pm_generic_runtime_resume+0x2c/0x40) from [<c031f07c>] (__rpm_callback+0x34/0x70)
> [ 0.516296] [<c031f07c>] (__rpm_callback+0x34/0x70) from [<c0320040>] (rpm_resume+0x3bc/0x648)
> [ 0.516326] [<c0320040>] (rpm_resume+0x3bc/0x648) from [<c0320548>] (__pm_runtime_resume+0x48/0x60)
> [ 0.516326] [<c0320548>] (__pm_runtime_resume+0x48/0x60) from [<c0331bf0>] (usbhs_omap_probe+0x200/0x840)
> [ 0.516357] [<c0331bf0>] (usbhs_omap_probe+0x200/0x840) from [<c0317d24>] (platform_drv_probe+0x18/0x1c)
> [ 0.516387] [<c0317d24>] (platform_drv_probe+0x18/0x1c) from [<c0316ae4>] (driver_probe_device+0x78/0x210)
> [ 0.516387] [<c0316ae4>] (driver_probe_device+0x78/0x210) from [<c0316d10>] (__driver_attach+0x94/0x98)
> [ 0.516418] [<c0316d10>] (__driver_attach+0x94/0x98) from [<c03153e4>] (bus_for_each_dev+0x50/0x7c)
> [ 0.516448] [<c03153e4>] (bus_for_each_dev+0x50/0x7c) from [<c0316310>] (bus_add_driver+0x178/0x240)
> [ 0.516448] [<c0316310>] (bus_add_driver+0x178/0x240) from [<c03171dc>] (driver_register+0x78/0x144)
> [ 0.516479] [<c03171dc>] (driver_register+0x78/0x144) from [<c0317f14>] (platform_driver_probe+0x18/0x9c)
> [ 0.516479] [<c0317f14>] (platform_driver_probe+0x18/0x9c) from [<c00086e4>] (do_one_initcall+0x34/0x178)
> [ 0.516510] [<c00086e4>] (do_one_initcall+0x34/0x178) from [<c06ea8f8>] (kernel_init_freeable+0xfc/0x1cc)
> [ 0.516571] [<c06ea8f8>] (kernel_init_freeable+0xfc/0x1cc) from [<c04d7a78>] (kernel_init+0x8/0xe4)
> [ 0.516571] [<c04d7a78>] (kernel_init+0x8/0xe4) from [<c000dd10>] (ret_from_fork+0x14/0x24)
> [ 0.516693] ---[ end trace e713e7725948e018 ]---
This WARN gets tripped when a clock is enabled but not prepared. From
__clk_enable in drivers/clk/clk.c:
if (WARN_ON(clk->prepare_count == 0))
return -ESHUTDOWN;
So we're basically dereferencing a bogus struct clk pointer in
__clk_enable and the memory address of clk->prepare_count just happens
to be zero filled.
On a related note, even if the clk_get lookup did not fail this WARN
would still be hit since this driver never once calls clk_prepare.
Regards,
Mike
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