Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932793AbbLRQKi (ORCPT ); Fri, 18 Dec 2015 11:10:38 -0500 Received: from mx1.redhat.com ([209.132.183.28]:35357 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932151AbbLRQKg (ORCPT ); Fri, 18 Dec 2015 11:10:36 -0500 Date: Fri, 18 Dec 2015 17:10:31 +0100 From: Benjamin Tissoires To: Mika Westerberg Cc: Nish Aravamudan , Jiri Kosina , Andrew Duggan , Gabriele Mazzotta , Seth Forshee , Dan Carpenter , linux-input@vger.kernel.org, "linux-kernel@vger.kernel.org" Subject: Re: [RESEND] Lenovo Yoga 900 touchpad issues Message-ID: <20151218161031.GB12730@mail.corp.redhat.com> References: <20151216092858.GP1762@lahna.fi.intel.com> <20151218144209.GK1762@lahna.fi.intel.com> <20151218153802.GL1762@lahna.fi.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20151218153802.GL1762@lahna.fi.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3275 Lines: 93 On Dec 18 2015 or thereabouts, Mika Westerberg wrote: > On Fri, Dec 18, 2015 at 04:42:09PM +0200, Mika Westerberg wrote: > > On another occasion the faulty input report was received immediatelly > > after we call i2c_hid_set_power(). > > > > With below hack patch suspend/resume works fine but it is far from being > > suitable for merging. Still, it would be nice if you could try it out > > and see if it helps in your case. > > Actually it looks like we can handle this by just ignoring input reports > while we are resetting the device. Following seems to work as well. Yes, I like this one better. I think, it is still prone to races, but it's a much better option. After turning this around, I think I finally got what was going on (and yes, it's basically a race that should have been caught long ago): - during resume, the i2c-hid driver calls reset, which is a long (few ms) operation. - hid-multitouch is also called during resume, and right after i2c-hid - hid-multiotuch immediately emits for touchpads a set input mode (this was unseen with touchscreens because they do not have to be switched into a proper mode) - there is a race between hid-multitouch accessing the features while the device is still resetting. And our reset interrupt never gets to us because there was an other operation in progress to request/set reports So the actual fix would be to make hid-multitouch wait until we reset i2c-hid. This should be done by either a mutex or a spinlock in i2c_hid_output_raw_report() and i2c_hid_resume() that would protect a flag set during suspend and cleared after resume. (not sure if this is clear :-P ) Cheers, Benjamin > > diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c > index 10bd8e6..eeaf33a 100644 > --- a/drivers/hid/i2c-hid/i2c-hid.c > +++ b/drivers/hid/i2c-hid/i2c-hid.c > @@ -352,13 +352,24 @@ static int i2c_hid_set_power(struct i2c_client *client, int power_state) > static int i2c_hid_hwreset(struct i2c_client *client) > { > struct i2c_hid *ihid = i2c_get_clientdata(client); > + bool started; > int ret; > > i2c_hid_dbg(ihid, "%s\n", __func__); > > + /* > + * Some touchpads seem to send input reports once their power is > + * turned back on after resume. This confuses our reset logic > + * below. > + * > + * Prevent handling any input reports while we are resetting the > + * device. > + */ > + started = test_and_clear_bit(I2C_HID_STARTED, &ihid->flags); > + > ret = i2c_hid_set_power(client, I2C_HID_PWR_ON); > if (ret) > - return ret; > + goto out; > > i2c_hid_dbg(ihid, "resetting...\n"); > > @@ -366,10 +377,14 @@ static int i2c_hid_hwreset(struct i2c_client *client) > if (ret) { > dev_err(&client->dev, "failed to reset device.\n"); > i2c_hid_set_power(client, I2C_HID_PWR_SLEEP); > - return ret; > + goto out; > } > > - return 0; > +out: > + if (started) > + set_bit(I2C_HID_STARTED, &ihid->flags); > + > + return ret; > } > > static void i2c_hid_get_input(struct i2c_hid *ihid) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/