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From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
Cc: devicetree@vger.kernel.org, eddie.cai.linux@gmail.com,
	kernel@collabora.com, heiko@sntech.de,
	jacob2.chen@rock-chips.com, Dafna Hirschfeld <dafna3@gmail.com>,
	jeffy.chen@rock-chips.com, zyc@rock-chips.com,
	linux-kernel@vger.kernel.org, tfiga@chromium.org,
	Allon Huang <allon.huang@rock-chips.com>,
	linux-rockchip@lists.infradead.org,
	Helen Koike <helen.koike@collabora.com>,
	Jacob Chen <cc@rock-chips.com>,
	hans.verkuil@cisco.com, laurent.pinchart@ideasonboard.com,
	zhengsq@rock-chips.com, mchehab@kernel.org,
	ezequiel@collabora.com, linux-arm-kernel@lists.infradead.org,
	linux-media@vger.kernel.org
Subject: Re: [PATCH v8 05/14] media: rkisp1: add Rockchip ISP1 subdev driver
Date: Wed, 12 Feb 2020 23:13:17 +0200
Message-ID: <20200212211317.GD3087@kekkonen.localdomain> (raw)
In-Reply-To: <78856358-1afd-31a7-86dd-22f7d6d7fb05@collabora.com>

Hi Dafna,

Apologies for the late reply. I learned the mail had got lost due to mail
server issues.

On Fri, Jan 31, 2020 at 08:38:34PM +0100, Dafna Hirschfeld wrote:
> Hi,
> I (Dafna Hirschfeld) will work in following months with Helen Koike to fix the issues
> in the TODO file of this driver: drivers/staging/media/rkisp1/TODO
> 
> On 15.08.19 15:17, Sakari Ailus wrote:
> > On Thu, Aug 15, 2019 at 11:24:22AM +0300, Sakari Ailus wrote:
> > > Hi Helen,
> > > 
> > > On Wed, Aug 14, 2019 at 09:58:05PM -0300, Helen Koike wrote:
> > > 
> > > ...
> > > 
> > > > > > +static int rkisp1_isp_sd_set_fmt(struct v4l2_subdev *sd,
> > > > > > +				 struct v4l2_subdev_pad_config *cfg,
> > > > > > +				 struct v4l2_subdev_format *fmt)
> > > > > > +{
> > > > > > +	struct rkisp1_device *isp_dev = sd_to_isp_dev(sd);
> > > > > > +	struct rkisp1_isp_subdev *isp_sd = &isp_dev->isp_sdev;
> > > > > > +	struct v4l2_mbus_framefmt *mf = &fmt->format;
> > > > > > +
> > > > > 
> > > > > Note that for sub-device nodes, the driver is itself responsible for
> > > > > serialising the access to its data structures.
> > > > 
> > > > But looking at subdev_do_ioctl_lock(), it seems that it serializes the
> > > > ioctl calls for subdevs, no? Or I'm misunderstanding something (which is
> > > > most probably) ?
> > > 
> > > Good question. I had missed this change --- subdev_do_ioctl_lock() is
> > > relatively new. But setting that lock is still not possible as the struct
> 
> 'the struct' - do you mean the 'vdev' struct allocated in
> 'v4l2_device_register_subdev_nodes' ?

Yes.

> 
> > > is allocated in the framework and the device is registered before the
> 
> > > driver gets hold of it. It's a good idea to provide the same serialisation
> > > for subdevs as well.
> > > 
> > > I'll get back to this later.
> > 
> > The main reason is actually that these ops are also called through the
> > sub-device kAPI, not only through the uAPI, and the locks are only taken
> > through the calls via uAPI.
> 
> actually it seems that although 'subdev_do_ioctl_lock' exit, I wonder if
> any subdevice uses that vdev->lock in  subdev_do_ioctl_lock.
> It is not initialized in v4l2_device_register_subdev_nodes where the vdev is allocated
> and I wonder if any subdevice actually initialize it somewhere else. For example it is null in this
> driver and in vimc.

It needs to be set before the video device is registered, so indeed, it
seems no driver can make use it.

> 
> > 
> > So adding the locks to uAPI calls alone would not address the issue.
> 
> What I can do is add a mutex to every struct of a subdevice and lock it
> at the beginning of each subdevice operation.
> Is this an acceptable solution?

Please do. That's what other drivers do at the moment as well.

-- 
Kind regards,

Sakari Ailus

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Thread overview: 76+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-30 18:42 [PATCH v8 00/14] Rockchip ISP1 Driver Helen Koike
2019-07-30 18:42 ` [PATCH v8 01/14] media: videodev2.h, v4l2-ioctl: add rkisp1 meta buffer format Helen Koike
2019-08-15 13:30   ` Laurent Pinchart
2019-07-30 18:42 ` [PATCH v8 02/14] media: doc: add document for " Helen Koike
2019-08-07 13:09   ` Sakari Ailus
2019-08-15 13:51   ` Laurent Pinchart
2019-07-30 18:42 ` [PATCH v8 03/14] media: rkisp1: Add user space ABI definitions Helen Koike
2019-08-15 18:46   ` Laurent Pinchart
2020-07-10 12:59     ` Dafna Hirschfeld
2020-07-10 13:36       ` Laurent Pinchart
2020-07-10 14:30         ` Dafna Hirschfeld
2019-07-30 18:42 ` [PATCH v8 04/14] media: rkisp1: add Rockchip MIPI Synopsys DPHY driver Helen Koike
2019-08-07 13:05   ` Sakari Ailus
2019-08-07 13:37     ` Helen Koike
2019-08-15 17:54       ` Laurent Pinchart
2019-08-15 18:26         ` Heiko Stübner
2019-08-21 21:46         ` Helen Koike
2019-08-22  2:32           ` Laurent Pinchart
2019-07-30 18:42 ` [PATCH v8 05/14] media: rkisp1: add Rockchip ISP1 subdev driver Helen Koike
2019-08-06 18:51   ` Helen Koike
2019-08-07 10:39     ` Hans Verkuil
2019-08-15 19:35       ` Laurent Pinchart
2020-03-25  6:34         ` Dafna Hirschfeld
2020-03-25  7:11           ` Laurent Pinchart
2020-03-25  8:51             ` Dafna Hirschfeld
2020-03-25  9:11               ` Laurent Pinchart
2019-08-08  9:14   ` Sakari Ailus
2019-08-15  0:58     ` Helen Koike
2019-08-15  8:24       ` Sakari Ailus
2019-08-15 10:29         ` Tomasz Figa
2019-08-15 10:45           ` Sakari Ailus
2019-08-15 13:17         ` Sakari Ailus
2020-01-31 19:38           ` Dafna Hirschfeld
2020-02-12 21:13             ` Sakari Ailus [this message]
2020-02-13 12:50               ` Dafna Hirschfeld
2019-08-16  0:13   ` Laurent Pinchart
2020-07-11 11:04     ` Dafna Hirschfeld
2020-07-17  7:46       ` Dafna Hirschfeld
2020-07-22 16:01         ` Tomasz Figa
2020-07-22 15:24       ` Tomasz Figa
2020-07-22 16:30         ` Laurent Pinchart
2020-07-22 17:12           ` Tomasz Figa
2020-07-22 17:50             ` Laurent Pinchart
2020-08-05 21:10         ` Dafna Hirschfeld
2020-08-06  9:21           ` Dafna Hirschfeld
2020-08-06 12:22             ` Tomasz Figa
2020-08-07 16:08               ` Dafna Hirschfeld
2020-08-13  6:17                 ` Dafna Hirschfeld
2020-08-06 12:08           ` Tomasz Figa
2020-08-07 16:02             ` Dafna Hirschfeld
2019-07-30 18:42 ` [PATCH v8 06/14] media: rkisp1: add ISP1 statistics driver Helen Koike
2019-08-08  9:37   ` Sakari Ailus
2019-07-30 18:42 ` [PATCH v8 07/14] media: rkisp1: add ISP1 params driver Helen Koike
2019-07-30 18:42 ` [PATCH v8 09/14] media: rkisp1: add rockchip isp1 core driver Helen Koike
2019-08-07 15:27   ` Sakari Ailus
2019-08-08 21:59     ` Helen Koike
2019-08-09 12:05       ` Sakari Ailus
2019-08-07 15:36   ` Sakari Ailus
2019-07-30 18:42 ` [PATCH v8 10/14] dt-bindings: Document the Rockchip ISP1 bindings Helen Koike
2019-08-16  0:21   ` Laurent Pinchart
2019-07-30 18:42 ` [PATCH v8 11/14] dt-bindings: Document the Rockchip MIPI RX D-PHY bindings Helen Koike
2019-08-15 18:14   ` Laurent Pinchart
2019-07-30 18:42 ` [PATCH v8 12/14] arm64: dts: rockchip: add isp0 node for rk3399 Helen Koike
2019-07-30 18:42 ` [PATCH v8 13/14] arm64: dts: rockchip: add rx0 mipi-phy " Helen Koike
2019-07-30 18:42 ` [PATCH v8 14/14] MAINTAINERS: add entry for Rockchip ISP1 driver Helen Koike
2019-08-15 13:56   ` Laurent Pinchart
2019-07-30 20:15 ` [PATCH v8 00/14] Rockchip ISP1 Driver Hans Verkuil
2019-07-30 20:50   ` Helen Koike
2019-07-31  0:08     ` Helen Koike
2019-07-31  4:29       ` Hans Verkuil
2019-07-31  4:33         ` Hans Verkuil
2019-07-31  4:55           ` Hans Verkuil
2019-07-31 14:42             ` Helen Koike
2019-08-07 15:37 ` Sakari Ailus
2019-08-07 17:57   ` Helen Koike
2019-08-09 18:45 ` Manivannan Sadhasivam

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