From mboxrd@z Thu Jan 1 00:00:00 1970 From: Charles Keepax Subject: Re: [PATCH] i2c: Allow recovery of the initial IRQ by an I2C client device. Date: Fri, 22 Feb 2019 10:28:36 +0000 Message-ID: <20190222102836.GC130153@ediswmail.ad.cirrus.com> References: <20190219193027.13882-1-jbroadus@gmail.com> <20190221232609.d4vxl3osj6mwooey@katana> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Benjamin Tissoires Cc: Wolfram Sang , Jim Broadus , Linux I2C , lkml List-Id: linux-i2c@vger.kernel.org On Fri, Feb 22, 2019 at 11:15:59AM +0100, Benjamin Tissoires wrote: > On Fri, Feb 22, 2019 at 12:26 AM Wolfram Sang wrote: > > On Tue, Feb 19, 2019 at 11:30:27AM -0800, Jim Broadus wrote: > > > A previous change allowed I2C client devices to discover new IRQs upon > > > reprobe by clearing the IRQ in i2c_device_remove. However, if an IRQ was > > > assigned in i2c_new_device, that information is lost. > > > > > > For example, the touchscreen and trackpad devices on a Dell Inspiron laptop > > > are I2C devices whose IRQs are defined by ACPI extended IRQ types. The > > > client device structures are initialized during an ACPI walk. After > > > removing the i2c_hid device, modprobe fails. > > > > > > This change caches the initial IRQ value in i2c_new_device and then resets > > > the client device IRQ to the initial value in i2c_device_remove. > > > > > > Fixes: 6f108dd70d30 ("i2c: Clear client->irq in i2c_device_remove") > > > Signed-off-by: Jim Broadus > > > > Adding Benjamin to CC > > Sorry, I should have answered earlier. > > I am a little bit hesitant regarding this patch. The effect is > correct, and I indeed realized a few weeks ago that something were > wrong as we couldn't rmmod/modprobe i2c-hid. > > But I still have the feeling that the problem is not solved at the > right place. In i2c_new_device() we are storing parts of the fields of > struct i2c_board_info, and when resetting the irq we are losing > information. This patch solves that, but I wonder if the IRQ should > not be 'simply' set in i2c_device_probe(). This means we also need to > store the .resources of info, but I have a feeling this will be less > error prone in the future. > I would be somewhat inclined to agree here, it does seem odd that on some paths we are allocating the IRQ on the new_device side and on some on the probe side. > But this is just my guts telling me something is not right. I would > perfectly understand if we want to get this merged ASAP. > > So given that the code is correct, this is my: > Reviewed-by: Benjamin Tissoires > This would be my thinking as well we should merge this to avoid the regression. Thanks, Charles