From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dmitry Torokhov Subject: Re: [PATCH 2/3] Input: zforce - enable irq only if we are ready to process it Date: Mon, 20 Jul 2015 09:54:43 -0700 Message-ID: <20150720165443.GA30252@dtor-ws> References: <1436791779-21798-1-git-send-email-dirk.behme@de.bosch.com> <1436791779-21798-2-git-send-email-dirk.behme@de.bosch.com> <20150713170735.GC5039@dtor-ws> <55A4AEEF.4020300@de.bosch.com> <20150717215847.GD39282@dtor-ws> <55AC84D9.2080809@de.bosch.com> <20150720063523.GD13092@dtor-ws> <55AC9C57.4070400@de.bosch.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail-pd0-f172.google.com ([209.85.192.172]:33647 "EHLO mail-pd0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751052AbbGTQys (ORCPT ); Mon, 20 Jul 2015 12:54:48 -0400 Received: by pdbnt7 with SMTP id nt7so33432724pdb.0 for ; Mon, 20 Jul 2015 09:54:48 -0700 (PDT) Content-Disposition: inline In-Reply-To: <55AC9C57.4070400@de.bosch.com> Sender: linux-input-owner@vger.kernel.org List-Id: linux-input@vger.kernel.org To: "external.Oleksij.Rempel" Cc: Dirk Behme , linux-input@vger.kernel.org On Mon, Jul 20, 2015 at 08:59:35AM +0200, external.Oleksij.Rempel wrote: > On 20.07.2015 08:35, Dmitry Torokhov wrote: > >On Mon, Jul 20, 2015 at 07:19:21AM +0200, external.Oleksij.Rempel wrote: > >>Hi Dmitry, > >> > >> > >>On 17.07.2015 23:58, Dmitry Torokhov wrote: > >>>Hi Oleksij, > >>> > >>>On Tue, Jul 14, 2015 at 08:40:47AM +0200, external.Oleksij.Rempel wrote: > >>>>Hi Dmitry, > >>>> > >>>>On 13.07.2015 19:07, Dmitry Torokhov wrote: > >>>>>On Mon, Jul 13, 2015 at 02:49:38PM +0200, Dirk Behme wrote: > >>>>>>From: Oleksij Rempel > >>>>>> > >>>>>>If zforce is not ready to process the interrupt, the touchscreen will > >>>>>>be lost forever. Make sure we enable the interrupt only if processing > >>>>>>is ready. > >>>>>> > >>>>>>Signed-off-by: Oleksij Rempel > >>>>>>Signed-off-by: Dirk Behme > >>>>>>--- > >>>>>> drivers/input/touchscreen/zforce_ts.c | 7 ++++++- > >>>>>> 1 file changed, 6 insertions(+), 1 deletion(-) > >>>>>> > >>>>>>diff --git a/drivers/input/touchscreen/zforce_ts.c b/drivers/input/touchscreen/zforce_ts.c > >>>>>>index 19dc297..a1889e5 100644 > >>>>>>--- a/drivers/input/touchscreen/zforce_ts.c > >>>>>>+++ b/drivers/input/touchscreen/zforce_ts.c > >>>>>>@@ -22,6 +22,7 @@ > >>>>>> #include > >>>>>> #include > >>>>>> #include > >>>>>>+#include > >>>>>> #include > >>>>>> #include > >>>>>> #include > >>>>>>@@ -741,6 +742,7 @@ static int zforce_probe(struct i2c_client *client, > >>>>>> struct zforce_ts *ts; > >>>>>> struct input_dev *input_dev; > >>>>>> int ret; > >>>>>>+ unsigned int irq; > >>>>>> if (!pdata) { > >>>>>> pdata = zforce_parse_dt(&client->dev); > >>>>>>@@ -835,6 +837,7 @@ static int zforce_probe(struct i2c_client *client, > >>>>>> init_completion(&ts->command_done); > >>>>>>+ irq = client->irq; > >>>>>> /* > >>>>>> * The zforce pulls the interrupt low when it has data ready. > >>>>>> * After it is triggered the isr thread runs until all the available > >>>>>>@@ -842,7 +845,8 @@ static int zforce_probe(struct i2c_client *client, > >>>>>> * Therefore we can trigger the interrupt anytime it is low and do > >>>>>> * not need to limit it to the interrupt edge. > >>>>>> */ > >>>>>>- ret = devm_request_threaded_irq(&client->dev, client->irq, > >>>>>>+ irq_set_status_flags(irq, IRQ_NOAUTOEN); > >>>>>Instead of playing with the flags should we simply request irq after we > >>>>>release the reset pin? > >>>>Because we should be able to process the interrupt. If i put > >>>>request_irq after reset, some times the interrupt can be missed. > >>>OK, I see that enabling after reset is racy. But I am still confused why > >>>having IRQ enabled while reste pin is asserted results in lost > >>>touchscreen. Can you walk me through the sequence of events? > >>> > >>>Thanks. > >>Mostly it will fail if zforce attached over SerDes > >>(Serializer/Deserializer). If we register IRQ after release of reset > >>pin, SerDes will get irq just before it has irq handler. In this > >>case irq will be lost, which means, not BOOT event will be passed to > >>the zforce. > >Yes, I agreed that requesting interrupt after releasing reset pin is not > >a good idea. But what is the issue with the original code that requests > >interrupt first (and enables it) and then releases the reset pin? > > If i remember it correctly SerDes will catch spurious interrupt from > the line and trigger it before client data was set. This means, > interrupt handler will need extra sanity checks. Client data is only referenced in suspend/resume routines though and they are not called until registration is completed. Thanks. -- Dmitry