From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH 2/5] input: twl6040-vibra: add handler to unregister input if module is removed Date: Tue, 19 Apr 2016 09:53:25 -0700 Message-ID: <20160419165325.GA2881@dtor-ws> References: <89f53877b821049c789256dd1b0c0b1dbb604de9.1461009340.git.hns@goldelico.com> <20160418211257.GA1006@dtor-ws> <20160419075705.GA13933@dtor-ws> <2C8A7B47-516D-4AA0-8231-16015387FA86@goldelico.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pa0-f44.google.com ([209.85.220.44]:33321 "EHLO mail-pa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753303AbcDSQx3 (ORCPT ); Tue, 19 Apr 2016 12:53:29 -0400 Content-Disposition: inline In-Reply-To: <2C8A7B47-516D-4AA0-8231-16015387FA86@goldelico.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: "H. Nikolaus Schaller" Cc: Fabio Estevam , Peter Ujfalusi , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pyra-handheld.com, letux-kernel@openphoenux.org On Tue, Apr 19, 2016 at 10:05:08AM +0200, H. Nikolaus Schaller wrote: > > > Am 19.04.2016 um 09:57 schrieb Dmitry Torokhov : > > > > On Tue, Apr 19, 2016 at 09:33:10AM +0200, H. Nikolaus Schaller wrote: > >> > >>> Am 18.04.2016 um 23:12 schrieb Dmitry Torokhov : > >>> > >>> On Mon, Apr 18, 2016 at 09:55:38PM +0200, H. Nikolaus Schaller wrote: > >>>> commit 1f9e1470ab34 ("Input: twl6040-vibra - use devm functions") > >>>> > >>>> converted everything to devm but we still need to call > >>>> input_unregister_device(info->input_dev) > >>> > >>> No, this is not needed, because devm-managed input devices will be > >>> unregistered automatically. > >> > >> Well, it would, if the current driver would use devm for registration. But it appears not to do it that way (line 375): > >> > >> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/input/misc/twl6040-vibra.c?id=refs/tags/v4.6-rc4#n375 > >> > >> So we either have to fix line 375 or add the proposed explicit unregister call. > >> > >> Research shows me that you did propose devm_input_register_device() some years ago but this API was never included: > >> > >> https://lkml.org/lkml/2012/10/29/855 > > > > That's because we have what I mentioned in _OR_ portion of that email: > > > > /** > > * devm_input_allocate_device - allocate managed input device > > * @dev: device owning the input device being created > > * > > * Returns prepared struct input_dev or %NULL. > > * > > * Managed input devices do not need to be explicitly unregistered or > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > * freed as it will be done automatically when owner device unbinds from > > * its driver (or binding fails). Once managed input device is allocated, > > * it is ready to be set up and registered in the same fashion as regular > > * input device. There are no special devm_input_device_[un]register() > > * variants, regular ones work with both managed and unmanaged devices, > > * should you need them. In most cases however, managed input device need > > * not be explicitly unregistered or freed. > > * > > * NOTE: the owner device is set up as parent of input device and users > > * should not override it. > > */ > > > > Hm. If I remember correctly (it is a while ago) we had to add this explicit > unregister mechanism because we got ugly kernel panics otherwise. Indicating > that the input device was still registered and *not* unregistered automatically. Ah, it is probably because we are messing up with input device's parent. Can you please try the patch below? Thanks. -- Dmitry Input: twl6040-vibra - do not reparent to grandparent From: Dmitry Torokhov For devm-managed input devices we should not modify input device's parent, otherwise automatic release of resources will not work properly. Signed-off-by: Dmitry Torokhov --- drivers/input/misc/twl6040-vibra.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/input/misc/twl6040-vibra.c b/drivers/input/misc/twl6040-vibra.c index 0c853c2..53e33fa 100644 --- a/drivers/input/misc/twl6040-vibra.c +++ b/drivers/input/misc/twl6040-vibra.c @@ -357,7 +357,6 @@ static int twl6040_vibra_probe(struct platform_device *pdev) info->input_dev->name = "twl6040:vibrator"; info->input_dev->id.version = 1; - info->input_dev->dev.parent = pdev->dev.parent; info->input_dev->close = twl6040_vibra_close; __set_bit(FF_RUMBLE, info->input_dev->ffbit);