From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCA88C32771 for ; Fri, 19 Aug 2022 07:35:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346540AbiHSHfu (ORCPT ); Fri, 19 Aug 2022 03:35:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346683AbiHSHfV (ORCPT ); Fri, 19 Aug 2022 03:35:21 -0400 X-Greylist: delayed 1133 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Fri, 19 Aug 2022 00:35:19 PDT Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 806F982FB8; Fri, 19 Aug 2022 00:35:19 -0700 (PDT) Received: (Authenticated sender: jacopo@jmondi.org) by mail.gandi.net (Postfix) with ESMTPSA id 9667A20002; Fri, 19 Aug 2022 07:35:14 +0000 (UTC) Date: Fri, 19 Aug 2022 09:35:12 +0200 From: Jacopo Mondi To: Marco Felsch Cc: mchehab@kernel.org, sakari.ailus@linux.intel.com, laurent.pinchart+renesas@ideasonboard.com, jacopo+renesas@jmondi.org, akinobu.mita@gmail.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@pengutronix.de Subject: Re: [PATCH 4/4] media: mt9m111: remove .s_power callback Message-ID: <20220819073512.ulud7ppnrudxewdn@uno.localdomain> References: <20220818144712.997477-1-m.felsch@pengutronix.de> <20220818144712.997477-4-m.felsch@pengutronix.de> <20220818161408.76ofg2rjvp5whtof@uno.localdomain> <20220819071832.3mr7u7jhp2ud4fv6@pengutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220819071832.3mr7u7jhp2ud4fv6@pengutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marco On Fri, Aug 19, 2022 at 09:18:32AM +0200, Marco Felsch wrote: > Hi Jacopo, > > thanks for your fast feedback :) > > On 22-08-18, Jacopo Mondi wrote: > > Hi Marco > > > > On Thu, Aug 18, 2022 at 04:47:12PM +0200, Marco Felsch wrote: > > > This is in preparation of switching to the generic dev PM mechanism. > > > Since the .s_power callback will be removed in the near future move the > > > powering into the .s_stream callback. So this driver no longer depends > > > on the .s_power mechanism. > > > > > > Signed-off-by: Marco Felsch > > > > If you want to move to runtime_pm, I would implement it first and have > > s_power call the _resume and _suspend routines, as some platform > > drivers still use s_power() and some of them might depend on it. > > Do we really have platforms which depend on this? IMHO if that is the $ git grep "v4l2_subdev_call(.*, s_power" drivers/media/platform/ | cut -d : -f1 | uniq | wc -l 8 > case than we should fix those platfoms. Since new drivers shouldn't use > this callback anymore. Patches are clearly welcome I guess.. > > In my case, I worked on [1] and wondered why the sensor was enabled > before I told him to do so. Since I didn't implement the s_power() > callback, I had no chance to get enabled before. > I'm not sure I got this part > Can we please decide: > - Do we wanna get rid of the s_power() callback? I think that would be everyone's desire, but drivers have to be moved away from it > - If not, how do we handle those devices then with drivers not > implementing this callback? By maintaining compatibility. I suggested to move to runtime_pm() and wrap _resume/_suspend in s_power(). My understanding is that the two (runtime_pm/s_power) are mutually exclusive, but even if that was not the case, runtime_pm is reference counted, hence as long as calls are balanced this should work, right ? > > [1] https://lore.kernel.org/all/20220818143307.967150-1-m.felsch@pengutronix.de/ > > > It's a slippery slope.. I would love to get rid of s_power() but if > > any platform uses it with this sensor, it would stop working after > > this change. > > > > > --- > > > drivers/media/i2c/mt9m111.c | 7 ++++++- > > > 1 file changed, 6 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/media/i2c/mt9m111.c b/drivers/media/i2c/mt9m111.c > > > index cd74c408e110..8e8ba5a8e6ea 100644 > > > --- a/drivers/media/i2c/mt9m111.c > > > +++ b/drivers/media/i2c/mt9m111.c > > > @@ -1065,7 +1065,6 @@ static const struct v4l2_ctrl_ops mt9m111_ctrl_ops = { > > > }; > > > > > > static const struct v4l2_subdev_core_ops mt9m111_subdev_core_ops = { > > > - .s_power = mt9m111_s_power, > > > .log_status = v4l2_ctrl_subdev_log_status, > > > .subscribe_event = v4l2_ctrl_subdev_subscribe_event, > > > .unsubscribe_event = v4l2_event_subdev_unsubscribe, > > > @@ -1136,8 +1135,14 @@ static int mt9m111_enum_mbus_code(struct v4l2_subdev *sd, > > > static int mt9m111_s_stream(struct v4l2_subdev *sd, int enable) > > > { > > > struct mt9m111 *mt9m111 = container_of(sd, struct mt9m111, subdev); > > > + int ret; > > > > > > mt9m111->is_streaming = !!enable; > > > + > > > + ret = mt9m111_s_power(sd, enable); > > > + if (ret) > > > + return ret; > > > + > > > return 0; > > > } > > > > > > -- > > > 2.30.2 > > > > >