From: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
To: Johan Hovold <johan@kernel.org>
Cc: Jacopo Mondi <jacopo@jmondi.org>,
linuxarm@huawei.com, mauro.chehab@huawei.com,
Hans Verkuil <hverkuil-cisco@xs4all.nl>,
Jacopo Mondi <jacopo+renesas@jmondi.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-kernel@vger.kernel.org, linux-media@vger.kernel.org
Subject: Re: [PATCH 38/78] media: i2c: mt9m001: use pm_runtime_resume_and_get()
Date: Wed, 28 Apr 2021 13:28:53 +0200 [thread overview]
Message-ID: <20210428132853.65b162a0@coco.lan> (raw)
In-Reply-To: <YIkzZs8t0lMWVjzt@hovoldconsulting.com>
Em Wed, 28 Apr 2021 12:05:26 +0200
Johan Hovold <johan@kernel.org> escreveu:
> On Wed, Apr 28, 2021 at 10:31:48AM +0200, Mauro Carvalho Chehab wrote:
> > Em Tue, 27 Apr 2021 14:23:20 +0200
> > Johan Hovold <johan@kernel.org> escreveu:
>
> > > You're call, but converting functioning drivers where the authors knew
> > > what they were doing just because you're not used to the API and risk
> > > introducing new bugs in the process isn't necessarily a good idea.
> >
> > The problem is that the above assumption is not necessarily true:
> > based on the number of drivers that pm_runtime_get_sync() weren't
> > decrementing usage_count on errors, several driver authors were not
> > familiar enough with the PM runtime behavior by the time the drivers
> > were written or converted to use the PM runtime, instead of the
> > media .s_power()/.s_stream() callbacks.
>
> That may very well be the case. My point is just that this work needs to
> be done carefully and by people familiar with the code (and runtime pm)
> or you risk introducing new issues.
Yeah, that's for sure.
> I really don't want the bot-warning-suppression crew to start with this
> for example.
>
> > > Especially since the pm_runtime_get_sync() will continue to be used
> > > elsewhere, and possibly even in media in cases where you don't need to
> > > check for errors (e.g. remove()).
> >
> > Talking about the remove(), I'm not sure if just ignoring errors
> > there would do the right thing. I mean, if pm_runtime_get_sync()
> > fails, probably any attempts to disable clocks and other things
> > that depend on PM runtime will also (silently) fail.
> >
> > This may put the device on an unknown PM and keep clock lines enabled
> > after its removal.
>
> Right, a resume failure is a pretty big issue and it's not really clear
> how to to even handle that generally. But at remove() time you don't
> have much choice but to go on and release resource anyway.
>
> So unless actually implementing some error handling too, using
> pm_runtime_sync_get() without checking for errors is still preferred
> over pm_runtime_resume_and_get(). That is
>
> pm_runtime_get_sync();
> /* cleanup */
> pm_runtime_disable()
> pm_runtime_put_noidle();
>
> is better than:
>
> ret = pm_runtime_resume_and_get();
> /* cleanup */
> pm_runtime_disable();
> if (ret == 0)
> pm_runtime_put_noidle();
>
> unless you also start doing something ret.
Perhaps the best would be to use, instead:
pm_runtime_get_noresume();
/* cleanup */
pm_runtime_disable()
pm_runtime_put_noidle();
pm_runtime_set_suspended();
I mean, at least for my eyes, it doesn't make sense to do a PM
resume during driver's removal/unbind time.
Regards,
Mauro
>
> Johan
Thanks,
Mauro
next prev parent reply other threads:[~2021-04-28 11:29 UTC|newest]
Thread overview: 127+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-24 6:44 [PATCH 00/78] media: use pm_runtime_resume_and_get() instead of pm_runtime_get_sync() Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 01/78] media: atmel: properly get pm_runtime Mauro Carvalho Chehab
2021-04-24 9:36 ` kernel test robot
2021-04-24 6:44 ` [PATCH 02/78] media: marvel-ccic: fix some issues when getting pm_runtime Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 03/78] media: mdk-mdp: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 04/78] media: rcar_fdp1: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 05/78] media: mdk-mdp: " Mauro Carvalho Chehab
2021-04-24 18:23 ` Ezequiel Garcia
2021-04-24 6:44 ` [PATCH 06/78] media: renesas-ceu: " Mauro Carvalho Chehab
2021-04-24 8:11 ` Jacopo Mondi
2021-04-24 6:44 ` [PATCH 07/78] media: s5p: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 08/78] media: am437x:: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 09/78] media: sh_vou: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 10/78] media: sti/hva: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 11/78] staging: media: rkvdec: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-04-24 23:20 ` Ezequiel Garcia
2021-04-24 6:44 ` [PATCH 12/78] staging: media: atomisp_fops: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 13/78] staging: media: hantro_drv: " Mauro Carvalho Chehab
2021-04-24 23:23 ` Ezequiel Garcia
2021-04-26 12:33 ` Mauro Carvalho Chehab
2021-04-26 12:42 ` Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 14/78] staging: media: imx7-mipi-csis: " Mauro Carvalho Chehab
2021-04-26 10:11 ` Rui Miguel Silva
2021-04-24 6:44 ` [PATCH 15/78] staging: media: ipu3: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 16/78] staging: media: cedrus_video: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 17/78] staging: media: vde: " Mauro Carvalho Chehab
2021-04-24 7:35 ` Dmitry Osipenko
2021-04-27 9:22 ` Mauro Carvalho Chehab
2021-04-27 12:34 ` Johan Hovold
2021-04-24 6:44 ` [PATCH 18/78] staging: media: csi: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 19/78] staging: media: vi: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 20/78] media: mtk-vcodec: fix pm_runtime_get_sync() usage count Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 21/78] media: s5p-jpeg: " Mauro Carvalho Chehab
2021-04-27 9:14 ` Sylwester Nawrocki
2021-04-24 6:44 ` [PATCH 22/78] media: delta-v4l2: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 23/78] media: sun8i_rotate: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 24/78] media: i2c: ak7375: use pm_runtime_resume_and_get() Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 25/78] media: i2c: ccs-core: " Mauro Carvalho Chehab
2021-04-25 18:55 ` Sakari Ailus
2021-04-26 14:01 ` Mauro Carvalho Chehab
2021-04-26 14:09 ` Sakari Ailus
2021-04-26 14:16 ` Mauro Carvalho Chehab
2021-04-26 14:29 ` Sakari Ailus
2021-04-26 17:32 ` Mauro Carvalho Chehab
2021-04-27 7:02 ` Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 26/78] media: i2c: dw9714: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 27/78] media: i2c: dw9768: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 28/78] media: i2c: dw9807-vcm: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 29/78] media: i2c: hi556: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 30/78] media: i2c: imx214: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 31/78] media: i2c: imx219: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 32/78] media: i2c: imx258: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 33/78] media: i2c: imx274: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 34/78] media: i2c: imx290: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 35/78] media: i2c: imx319: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 36/78] media: i2c: imx334: " Mauro Carvalho Chehab
2021-04-26 9:06 ` Alessandrelli, Daniele
2021-04-24 6:44 ` [PATCH 37/78] media: i2c: imx355: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 38/78] media: i2c: mt9m001: " Mauro Carvalho Chehab
2021-04-24 8:24 ` Jacopo Mondi
2021-04-24 10:00 ` Johan Hovold
2021-04-26 14:38 ` Mauro Carvalho Chehab
2021-04-27 12:23 ` Johan Hovold
2021-04-28 8:31 ` Mauro Carvalho Chehab
2021-04-28 10:05 ` Johan Hovold
2021-04-28 11:28 ` Mauro Carvalho Chehab [this message]
2021-04-28 11:56 ` Johan Hovold
2021-04-24 6:44 ` [PATCH 39/78] media: i2c: ov02a10: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 40/78] media: i2c: ov13858: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 41/78] media: i2c: ov2659: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 42/78] media: i2c: ov2685: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 43/78] media: i2c: ov2740: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 44/78] media: i2c: ov5647: " Mauro Carvalho Chehab
2021-04-24 8:30 ` Jacopo Mondi
2021-04-24 6:44 ` [PATCH 45/78] media: i2c: ov5648: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 46/78] media: i2c: ov5670: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 47/78] media: i2c: ov5675: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 48/78] media: i2c: ov5695: " Mauro Carvalho Chehab
2021-04-24 6:44 ` [PATCH 49/78] media: i2c: ov7740: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 50/78] media: i2c: ov8856: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 51/78] media: i2c: ov8865: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 52/78] media: i2c: ov9734: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 53/78] media: i2c: tvp5150: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 54/78] media: i2c: video-i2c: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 55/78] media: ipu3: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 56/78] media: coda: " Mauro Carvalho Chehab
2021-04-26 6:53 ` Philipp Zabel
2021-04-24 6:45 ` [PATCH 57/78] media: exynos4-is: " Mauro Carvalho Chehab
2021-04-25 20:57 ` Sylwester Nawrocki
2021-04-26 13:12 ` Mauro Carvalho Chehab
2021-04-27 8:06 ` Sylwester Nawrocki
2021-04-24 6:45 ` [PATCH 58/78] media: exynos-gsc: " Mauro Carvalho Chehab
2021-04-27 8:18 ` Sylwester Nawrocki
2021-04-27 9:30 ` Mauro Carvalho Chehab
2021-04-27 9:42 ` Mauro Carvalho Chehab
2021-04-27 11:50 ` Sylwester Nawrocki
2021-04-28 7:13 ` Mauro Carvalho Chehab
2021-04-28 7:17 ` Mauro Carvalho Chehab
2021-04-28 8:27 ` Sylwester Nawrocki
2021-04-24 6:45 ` [PATCH 59/78] media: mtk-jpeg: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 60/78] media: camss-csid: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 61/78] media: camss-csiphy: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 62/78] media: camss-ispif: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 63/78] media: camss-vfe: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 64/78] media: core: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 65/78] media: pm_helpers: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 66/78] media: vdec: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 67/78] media: venc: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 68/78] media: rcar-fcp: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 69/78] media: rcar-vin: " Mauro Carvalho Chehab
2021-04-24 8:33 ` Niklas Söderlund
2021-04-24 9:12 ` Geert Uytterhoeven
2021-04-26 13:33 ` Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 70/78] media: rga-buf: " Mauro Carvalho Chehab
2021-04-28 17:09 ` Ezequiel Garcia
2021-04-24 6:45 ` [PATCH 71/78] media: rkisp1-capture: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 72/78] media: s3c-camif: " Mauro Carvalho Chehab
2021-04-25 19:36 ` Sylwester Nawrocki
2021-04-24 6:45 ` [PATCH 73/78] media: s5p-mfc: " Mauro Carvalho Chehab
2021-04-27 9:36 ` Sylwester Nawrocki
2021-04-24 6:45 ` [PATCH 74/78] media: bdisp-v4l2: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 75/78] media: stm32: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 76/78] media: sun4i_v4l2: " Mauro Carvalho Chehab
2021-04-24 10:21 ` kernel test robot
2021-04-24 6:45 ` [PATCH 77/78] media: ti-vpe: " Mauro Carvalho Chehab
2021-04-24 6:45 ` [PATCH 78/78] media: vsp1: " Mauro Carvalho Chehab
2021-04-28 10:13 ` [PATCH 00/78] media: use pm_runtime_resume_and_get() instead of pm_runtime_get_sync() Dan Carpenter
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