From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: dinghao.liu@zju.edu.cn
Cc: kjlu@umn.edu,
Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: Re: [PATCH] media: vsp1: Fix runtime PM imbalance in vsp1_probe
Date: Mon, 8 Jun 2020 06:11:34 +0300 [thread overview]
Message-ID: <20200608031134.GO22208@pendragon.ideasonboard.com> (raw)
In-Reply-To: <7b79863f.f636d.17291e1ff94.Coremail.dinghao.liu@zju.edu.cn>
Hi Dianghao,
On Mon, Jun 08, 2020 at 11:03:26AM +0800, dinghao.liu@zju.edu.cn wrote:
> Hi Laurent,
>
> > > I wonder how many bugs we have today, and how many bugs will keep
> > > appearing in the future, due to this historical design mistake :-(
>
> Good question. It's hard to say if this is a design mistake (some use
> of this API does not check its return value and expects it always to
> increment the usage counter). But it does make developers misuse it easier.
>
> > > This change looks good to me, but we also need a similar change in the
> > > vsp1_device_get() function if I'm not mistaken. Could you combine both
> > > in the same patch ?
>
> Thank you for your advice! I think you are right and I will fix this in the
> next version of patch.
>
> > And actually, after fixing vsp1_device_get(), we should replace the
> > pm_runtime_get_sync() call here with vsp1_device_get(), and the
> > pm_runtime_put_sync() below with vsp1_device_put(), so there would be no
> > need to call pm_runtime_put_sync() manually in the error path here.
>
> The parameter type of vsp1_device_get() and vsp1_device_put() is "struct
> vsp1_device". If we want to use these two wrappers, we need to adjust their
> parameter type to "struct platform_device" or "struct device", which may
> lead to errors in other callers. Maybe we should leave it as it is.
The vsp1_probe() function has a struct vsp1_device whose dev field is
populated by the time it needs to call pm_runtime_get_sync() and
pm_runtime_get_put(), so I think you can use vsp1_device_get() and
vsp1_device_put() as drop-in replacements without changing the
parameters to these two functions.
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2020-06-08 3:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-23 11:54 [PATCH] media: vsp1: Fix runtime PM imbalance in vsp1_probe Dinghao Liu
2020-06-08 1:54 ` Laurent Pinchart
2020-06-08 1:57 ` Laurent Pinchart
2020-06-08 3:03 ` dinghao.liu
2020-06-08 3:11 ` Laurent Pinchart [this message]
2020-06-08 3:33 ` dinghao.liu
2020-06-08 7:39 ` Geert Uytterhoeven
2020-06-08 11:54 ` Laurent Pinchart
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