Date:	Wed, 08 Apr 2015 12:26:13 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
CC:	Vinod Koul <vinod.koul@...el.com>, Felipe Balbi <balbi@...com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Linux kernel <linux-kernel@...r.kernel.org>
Subject: Re: [4.0-rc+] WARNING: CPU: 0 PID: 1 at ./drivers/dma/dmaengine.c:863
 dma_async_device_register+0xe0/0x540()

Linus,

I just got an automated bounce reply from Vinod Koul stating
he's on vacation til April 12th, so I'd appreciate if you could
revert this commit [1] for 4.0-final.

The commit generates a WARNING [2] in a effort to get dmaengine drivers
to add new functionality.

I sent Vinod a note that this was happening on Beaglebone Blacks
back on Mar 5 (-rc3). He thought the functionality would be added
shortly, but it wasn't, so the WARNING is still happening on -rc7.

Regards,
Peter Hurley


On 04/08/2015 11:53 AM, Peter Hurley wrote:
> On 03/05/2015 11:12 AM, Vinod Koul wrote:
>> On Thu, Mar 05, 2015 at 10:04:21AM -0500, Peter Hurley wrote:
>>>> First boot of 4.0-rc+ gave me [1] on a Beaglebone Black due to
>>>>
>> The warning is intentional to get driver fixed and give the right behaviour
>>
>> Felipe had sent a patch for this but that one needs an update
> 
> Vinod,
> 
> Felipe's patch never made it to mainline, and this warning is 
> still happening on 4.0-rc7 so please revert for 4.0-final.
> 
> Regards,
> Peter Hurley
> 
> 
>> -- ~Vinod

[1]

>>>> commit ecc19d17868be9c9f8f00ed928791533c420f3e0
>>>> Author: Maxime Ripard <maxime.ripard@...e-electrons.com>
>>>> Date:   Mon Nov 17 14:42:53 2014 +0100
>>>>
>>>>     dmaengine: Add a warning for drivers not using the generic slave caps retrieval
>>>>     
>>>>     For the slave caps retrieval to be really useful, most drivers need to
>>>>     implement it.
>>>>     
>>>>     Hence, we need to be slightly more aggressive, and trigger a warning at
>>>>     registration time for drivers that don't fill their caps infos in order to
>>>>     encourage them to implement it.
>>>>     
>>>>     Signed-off-by: Maxime Ripard <maxime.ripard@...e-electrons.com>
>>>>     Acked-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>
>>>>     Signed-off-by: Vinod Koul <vinod.koul@...el.com>

[2]

>>>> [    1.848374] WARNING: CPU: 0 PID: 1 at /home/peter/src/kernels/mainline/drivers/dma/dmaengine.c:863 dma_async_device_register+0xe0/0x540()
>>>> [    1.860798] this driver doesn't support generic slave capabilities reporting
>>>> [    1.867893] Modules linked in:
>>>> [    1.870993] CPU: 0 PID: 1 Comm: swapper Not tainted 4.0.0-rc2+ #115
>>>> [    1.877302] Hardware name: Generic AM33XX (Flattened Device Tree)
>>>> [    1.883478] [<c00164b8>] (unwind_backtrace) from [<c00135e8>] (show_stack+0x20/0x24)
>>>> [    1.891307] [<c00135e8>] (show_stack) from [<c091f7a0>] (dump_stack+0x24/0x28)
>>>> [    1.898602] [<c091f7a0>] (dump_stack) from [<c003dff4>] (warn_slowpath_common+0x94/0xc0)
>>>> [    1.906753] [<c003dff4>] (warn_slowpath_common) from [<c003e060>] (warn_slowpath_fmt+0x40/0x48)
>>>> [    1.915515] [<c003e060>] (warn_slowpath_fmt) from [<c0561fd8>] (dma_async_device_register+0xe0/0x540)
>>>> [    1.924806] [<c0561fd8>] (dma_async_device_register) from [<c056b3cc>] (cppi41_dma_probe+0x470/0x4c0)
>>>> [    1.934397] [<c056b3cc>] (cppi41_dma_probe) from [<c05f7e6c>] (platform_drv_probe+0x54/0xb4)
>>>> [    1.942924] [<c05f7e6c>] (platform_drv_probe) from [<c05f5bac>] (driver_probe_device+0x14c/0x3a8)
>>>> [    1.951861] [<c05f5bac>] (driver_probe_device) from [<c05f5e58>] (__device_attach+0x50/0x54)
>>>> [    1.960360] [<c05f5e58>] (__device_attach) from [<c05f3c94>] (bus_for_each_drv+0x68/0x9c)
>>>> [    1.968596] [<c05f3c94>] (bus_for_each_drv) from [<c05f59ec>] (device_attach+0x84/0x98)
>>>> [    1.976656] [<c05f59ec>] (device_attach) from [<c05f4e70>] (bus_probe_device+0x94/0xb8)
>>>> [    1.984717] [<c05f4e70>] (bus_probe_device) from [<c05f2cb0>] (device_add+0x3dc/0x59c)
>>>> [    1.992700] [<c05f2cb0>] (device_add) from [<c07a6f5c>] (of_device_add+0x44/0x4c)
>>>> [    2.000242] [<c07a6f5c>] (of_device_add) from [<c07a78d4>] (of_platform_device_create_pdata+0x140/0x234)
>>>> [    2.009788] [<c07a78d4>] (of_platform_device_create_pdata) from [<c07a7af8>] (of_platform_bus_create+0x10c/0x234)
>>>> [    2.020118] [<c07a7af8>] (of_platform_bus_create) from [<c07a7dbc>] (of_platform_populate+0x6c/0xc8)
>>>> [    2.029319] [<c07a7dbc>] (of_platform_populate) from [<c06e83f8>] (am335x_child_probe+0x38/0x54)
>>>> [    2.038168] [<c06e83f8>] (am335x_child_probe) from [<c05f7e6c>] (platform_drv_probe+0x54/0xb4)
>>>> [    2.046840] [<c05f7e6c>] (platform_drv_probe) from [<c05f5bac>] (driver_probe_device+0x14c/0x3a8)
>>>> [    2.055774] [<c05f5bac>] (driver_probe_device) from [<c05f5ef8>] (__driver_attach+0x9c/0xa0)
>>>> [    2.064268] [<c05f5ef8>] (__driver_attach) from [<c05f3bcc>] (bus_for_each_dev+0x70/0xa4)
>>>> [    2.072501] [<c05f3bcc>] (bus_for_each_dev) from [<c05f555c>] (driver_attach+0x2c/0x30)
>>>> [    2.080561] [<c05f555c>] (driver_attach) from [<c05f515c>] (bus_add_driver+0x170/0x22c)
>>>> [    2.088623] [<c05f515c>] (bus_add_driver) from [<c05f6878>] (driver_register+0x88/0x108)
>>>> [    2.096770] [<c05f6878>] (driver_register) from [<c05f7d98>] (__platform_driver_register+0x64/0x6c)
>>>> [    2.105884] [<c05f7d98>] (__platform_driver_register) from [<c0d8df0c>] (am335x_child_init+0x1c/0x20)
>>>> [    2.115171] [<c0d8df0c>] (am335x_child_init) from [<c0008ad8>] (do_one_initcall+0xe8/0x230)
>>>> [    2.123592] [<c0008ad8>] (do_one_initcall) from [<c0d45f90>] (kernel_init_freeable+0x1e0/0x284)
>>>> [    2.132355] [<c0d45f90>] (kernel_init_freeable) from [<c0919044>] (kernel_init+0x1c/0x100)
>>>> [    2.140681] [<c0919044>] (kernel_init) from [<c000f8d0>] (ret_from_fork+0x14/0x24)

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