Linux-Media Archive on lore.kernel.org
 help / color / Atom feed
From: Dafna Hirschfeld <dafna.hirschfeld@collabora.com>
To: Dave Stevenson <dave.stevenson@raspberrypi.com>
Cc: Jacopo Mondi <jacopo@jmondi.org>,
	andrew_gabbasov@mentor.com,
	Dave Stevenson <dave.stevenson@raspberrypi.org>,
	mrodin@de.adit-jv.com, erosca@de.adit-jv.com,
	Maxime Ripard <mripard@kernel.org>,
	Roman Kovalivskyi <roman.kovalivskyi@globallogic.com>,
	libcamera-devel@lists.libcamera.org,
	Linux Media Mailing List <linux-media@vger.kernel.org>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	hugues.fruchet@st.com, Mauro Carvalho Chehab <mchehab@kernel.org>,
	aford173@gmail.com, sudipi@jp.adit-jv.com
Subject: Re: [libcamera-devel] [PATCH 20/25] media: ov5647: Program mode only if it has changed
Date: Tue, 30 Jun 2020 17:11:28 +0200
Message-ID: <887cd8b6-c82c-22b9-ce48-5881a8b51686@collabora.com> (raw)
In-Reply-To: <CAPY8ntAtTpvh=20d+tda+H5nodSNeNiHOL8xtAsgi92ctW3BLw@mail.gmail.com>



On 30.06.20 16:53, Dave Stevenson wrote:
> Hi Dafna
> 
> On Tue, 30 Jun 2020 at 14:01, Dafna Hirschfeld
> <dafna.hirschfeld@collabora.com> wrote:
>>
>> Hi,
>>
>>
>> On 30.06.20 14:05, Jacopo Mondi wrote:
>>> Hi Dafna,
>>>
>>> On Tue, Jun 30, 2020 at 12:56:44PM +0200, Dafna Hirschfeld wrote:
>>>>
>>>>
>>>> On 30.06.20 12:06, Jacopo Mondi wrote:
>>>>> Hi Dafna,
>>>>>
>>>>> On Tue, Jun 30, 2020 at 11:32:12AM +0200, Dafna Hirschfeld wrote:
>>>>>>
>>>>>>
>>>>>> On 30.06.20 09:43, Jacopo Mondi wrote:
>>>>>>> Hi Dafna,
>>>>>>>
>>>>>>> On Mon, Jun 29, 2020 at 07:48:16PM +0200, Dafna Hirschfeld wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>> On 23.06.20 18:55, Jacopo Mondi wrote:
>>>>>>>>> Store in the driver structure a pointer to the currently applied mode
>>>>>>>>> and program a new one at s_stream(1) time only if it has changed.
>>>>>>>>
>>>>>>>> Hi,
>>>>>>>> I think this can be more readably implemented with a 'is_streaming' boolean
>>>>>>>> field.
>>>>>>>
>>>>>>> How would you like to use an 'is_streaming' flag to decide if the
>>>>>>> sensor mode has to be updated ?
>>>>>>
>>>>>> since 'current_mode' is set to NULL upon `ov5647_stream_off`
>>>>>> and you return from 'ov5647_set_stream' immediately if 'mode == current_mode'
>>>>>> it seem very similar to returning immediately from 'ov5647_set_stream' if the
>>>>>> device is currently streaming.
>>>>>
>>>>> No, the code returns immediately from ov5647_set_mode() if mode ==
>>>>> current_mode. The modes comparison makes sure the sensor is not
>>>>> reprogrammed if the mode hasn't changed. The remaning part of
>>>>> s_stream() is executed regardless of the mode configuration. Am I
>>>>> missing some part of the picture ?
>>>>>
>>>>>>
>>>>>> But actually in this patch it seems to be possible to change the mode
>>>>>> while streaming, if the callbacks are executed:
>>>>>>
>>>>>> s_stream(1)
>>>>>> s_fmt
>>>>>> s_stream(1)
>>>>>>
>>>>>> which is maybe a bug?
>>>>>
>>>>> The new format is stored in sensor->mode, and applied at the next
>>>>> s_stream(1) operation if it differs from the already programmed one,
>>>>> at least, this is how it is intended to work, have you found any
>>>>> failing s_stream/set_fmt/s_stream which could be caused by a bug ?
>>>>
>>>> What I meant is that there could be valid sequence of calls
>>>>
>>>> s_stream(enable=1)
>>>> s_fmt
>>>> s_stream(enable=1)
>>>>
>>>> For example if two video devices are connected to the sensor and they
>>>> stream simultaneously. There was a discussion about adding a code to the core
>>>
>>> I'm not sure it is possible, given that the subdev has a single source
>>> pad
>>
>> Video devices should not be connected directly to the sensor,
> 
> That's an odd statement as it is exactly the situation we have on the
> Pi. The CSI2 receiver writes data to RAM, therefore it is a video
> device.
> Did you intend to say that it isn't necessarily connected directly to
> the sensor?
Yes, sorry, I meant, "they don't have to" (but they can).

> 
>> they can also
>> be connected to the sensor through an isp entity that is connected to the sensor
>> from one side and to two video devices from the other side.
> 
> It's true that some platforms will route the received CSI2 data
> straight through the ISP, and only write the processed image(s) to
> RAM. If there are multiple output video devices from the ISP then yes
> they will VIDIOC_STREAMON at different points.
> However is it really valid to call s_stream(1) on the sensor subdev
> for each of them? Doesn't that mean you really need refcounting of the
> number of s_stream(1)'s (and s_stream(0)'s) within each sensor driver,
> so that it only actually stops streaming on the last s_stream(0), not
> the first. A simple boolean isn't sufficient, otherwise
> VIDIOC_STREAMON(NODE_A);
> VIDIOC_STREAMON(NODE_B);
> VIDIOC_STREAMOFF(NODE_B);
> leaves you with no data from NODE_A even though it has never called
> VIDIOC_STREAMOFF.

oh, right, there was a proposal to add functions that do it with refcounting

https://patchwork.kernel.org/project/linux-media/list/?series=271153

Dafna


> 
> Anyway this patch was to remove excess writing of the mode registers if you did
> s_fmt
> s_stream(1)
> s_stream(0)
> s_stream(1)
> 
> The driver uses the s_power call rather than pm_runtime as that was an
> acceptable approach when it was written in 2017, so the power, and
> hence register settings, can be maintained between multiple s_stream
> calls.
> 
>    Dave
> 
>> Thanks,
>> D
>>
>>>
>>>> to follow the s_stream callback and call it only if the subdev is not streaming
>>>> but currently subdevs should support it themselves.
>>>>
>>>
>>> Oh, so you're concerned about the fact userspace can call s_stream(1)
>>> twice consecutively! it's indipendent from s_ftm if I got your point.
>>>
>>> In this case a flag to control if the device is streaming already should
>>> help, yes, I overlooked that indeed.
>>>
>>> Thanks
>>>     j
>>>
>>>>
>>>> Thanks,
>>>> Dafna
>>>>
>>>>>
>>>>> Thanks
>>>>>      j
>>>>>>
>>>>>> Thanks,
>>>>>> Dafna
>>>>>>
>>>>>>>
>>>>>>> Thanks
>>>>>>>        j
>>>>>>>
>>>>>>>
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Dafna
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>
>>>>>>>>> ---
>>>>>>>>>       drivers/media/i2c/ov5647.c | 16 +++++++++++++++-
>>>>>>>>>       1 file changed, 15 insertions(+), 1 deletion(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/media/i2c/ov5647.c b/drivers/media/i2c/ov5647.c
>>>>>>>>> index 39e320f321bd8..ac114269e1c73 100644
>>>>>>>>> --- a/drivers/media/i2c/ov5647.c
>>>>>>>>> +++ b/drivers/media/i2c/ov5647.c
>>>>>>>>> @@ -96,6 +96,7 @@ struct ov5647 {
>>>>>>>>>          bool                            clock_ncont;
>>>>>>>>>          struct v4l2_ctrl_handler        ctrls;
>>>>>>>>>          struct ov5647_mode              *mode;
>>>>>>>>> +       struct ov5647_mode              *current_mode;
>>>>>>>>>       };
>>>>>>>>>       static inline struct ov5647 *to_sensor(struct v4l2_subdev *sd)
>>>>>>>>> @@ -750,9 +751,13 @@ static int ov5647_set_virtual_channel(struct v4l2_subdev *sd, int channel)
>>>>>>>>>       static int ov5647_set_mode(struct v4l2_subdev *sd)
>>>>>>>>>       {
>>>>>>>>>          struct i2c_client *client = v4l2_get_subdevdata(sd);
>>>>>>>>> +       struct ov5647 *sensor = to_sensor(sd);
>>>>>>>>>          u8 resetval, rdval;
>>>>>>>>>          int ret;
>>>>>>>>> +       if (sensor->mode == sensor->current_mode)
>>>>>>>>> +               return 0;
>>>>>>>>> +
>>>>>>>>>          ret = ov5647_read(sd, OV5647_SW_STANDBY, &rdval);
>>>>>>>>>          if (ret < 0)
>>>>>>>>>                  return ret;
>>>>>>>>> @@ -778,6 +783,8 @@ static int ov5647_set_mode(struct v4l2_subdev *sd)
>>>>>>>>>                          return ret;
>>>>>>>>>          }
>>>>>>>>> +       sensor->current_mode = sensor->mode;
>>>>>>>>> +
>>>>>>>>>          return 0;
>>>>>>>>>       }
>>>>>>>>> @@ -816,6 +823,7 @@ static int ov5647_stream_on(struct v4l2_subdev *sd)
>>>>>>>>>       static int ov5647_stream_off(struct v4l2_subdev *sd)
>>>>>>>>>       {
>>>>>>>>> +       struct ov5647 *sensor = to_sensor(sd);
>>>>>>>>>          int ret;
>>>>>>>>>          ret = ov5647_write(sd, OV5647_REG_MIPI_CTRL00, MIPI_CTRL00_CLOCK_LANE_GATE |
>>>>>>>>> @@ -827,7 +835,13 @@ static int ov5647_stream_off(struct v4l2_subdev *sd)
>>>>>>>>>          if (ret < 0)
>>>>>>>>>                  return ret;
>>>>>>>>> -       return ov5647_write(sd, OV5640_REG_PAD_OUT, 0x01);
>>>>>>>>> +       ret = ov5647_write(sd, OV5640_REG_PAD_OUT, 0x01);
>>>>>>>>> +       if (ret < 0)
>>>>>>>>> +               return ret;
>>>>>>>>> +
>>>>>>>>> +       sensor->current_mode = NULL;
>>>>>>>>> +
>>>>>>>>> +       return 0;
>>>>>>>>>       }
>>>>>>>>>       static int set_sw_standby(struct v4l2_subdev *sd, bool standby)
>>>>>>>>>
>> _______________________________________________
>> libcamera-devel mailing list
>> libcamera-devel@lists.libcamera.org
>> https://lists.libcamera.org/listinfo/libcamera-devel

  reply index

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-23 10:07 [PATCH 00/25] media: ov5647: Support RaspberryPi Camera Module v1 Jacopo Mondi
2020-06-23 10:07 ` [PATCH 01/25] dt-bindings: media: ov5647: Document pwdn-gpios Jacopo Mondi
2020-06-23 10:07 ` [PATCH 02/25] dt-bindings: media: ov5647: Document clock-noncontinuous Jacopo Mondi
2020-06-23 10:07 ` [PATCH 03/25] media: ov5647: Add support for PWDN GPIO Jacopo Mondi
2020-07-09 20:04   ` [libcamera-devel] " Dafna Hirschfeld
2020-07-14 12:45     ` Jacopo Mondi
2020-06-23 10:07 ` [PATCH 04/25] media: ov5647: Add support for non-continuous clock mode Jacopo Mondi
2020-06-23 10:07 ` [PATCH 05/25] media: ov5647: Add set_fmt and get_fmt calls Jacopo Mondi
2020-06-23 10:07 ` [PATCH 06/25] media: ov5647: Fix format initialization Jacopo Mondi
2020-06-23 10:07 ` [PATCH 07/25] media: ov5647: Fix style issues Jacopo Mondi
2020-06-23 10:07 ` [PATCH 08/25] media: ov5647: Replace license with SPDX identifier Jacopo Mondi
2020-06-23 10:07 ` [PATCH 09/25] media: ov5647: Fix return value from read/write Jacopo Mondi
2020-06-23 10:08 ` [PATCH 10/25] media: ov5647: Program mode at s_stream(1) time Jacopo Mondi
2020-06-23 16:42 ` [PATCH 11/25] media: ov5647: Implement enum_frame_size() Jacopo Mondi
2020-08-18  7:33   ` Sakari Ailus
2020-08-18  7:38     ` Sakari Ailus
2020-06-23 16:42 ` [PATCH 12/25] media: ov5647: Protect s_stream() with mutex Jacopo Mondi
2020-06-23 16:42 ` [PATCH 13/25] media: ov5647: Support gain, exposure and AWB controls Jacopo Mondi
2020-06-23 16:42 ` [PATCH 14/25] media: ov5647: Rationalize driver structure name Jacopo Mondi
2020-06-23 16:42 ` [PATCH 15/25] media: ov5647: Break out format handling Jacopo Mondi
2020-07-31 11:44   ` Sakari Ailus
2020-06-23 16:49 ` [PATCH 16/25] media: ov5647: Add support for get_selection() Jacopo Mondi
2020-07-09 19:56   ` [libcamera-devel] " Dafna Hirschfeld
2020-06-23 16:49 ` [PATCH 17/25] media: ov5647: Rename SBGGR8 VGA mode Jacopo Mondi
2020-06-23 16:49 ` [PATCH 18/25] media: ov5647: Add SGGBR10_1X10 modes Jacopo Mondi
2020-06-23 16:49 ` [PATCH 19/25] media: ov5647: Implement set_fmt pad operation Jacopo Mondi
2020-06-29 16:54   ` [libcamera-devel] " Dafna Hirschfeld
2020-06-30 10:13     ` Jacopo Mondi
2020-06-30 11:09       ` Dafna Hirschfeld
2020-06-23 16:55 ` [PATCH 20/25] media: ov5647: Program mode only if it has changed Jacopo Mondi
2020-06-29 17:48   ` Dafna Hirschfeld
2020-06-30  7:43     ` Jacopo Mondi
2020-06-30  9:32       ` Dafna Hirschfeld
2020-06-30 10:06         ` Jacopo Mondi
2020-06-30 10:56           ` Dafna Hirschfeld
2020-06-30 12:05             ` Jacopo Mondi
2020-06-30 13:01               ` Dafna Hirschfeld
2020-06-30 14:53                 ` [libcamera-devel] " Dave Stevenson
2020-06-30 15:11                   ` Dafna Hirschfeld [this message]
2020-07-01  7:25                 ` Laurent Pinchart
2020-07-03 12:21                   ` Jacopo Mondi
2020-07-03 16:33                     ` Laurent Pinchart
2020-06-23 16:55 ` [PATCH 21/25] media: ov5647: Set V4L2_SUBDEV_FL_HAS_EVENTS flag Jacopo Mondi
2020-06-23 16:55 ` [PATCH 22/25] media: ov5647: Support V4L2_CID_PIXEL_RATE Jacopo Mondi
2020-06-29 17:01   ` [libcamera-devel] " Dafna Hirschfeld
2020-06-29 21:25     ` Dave Stevenson
2020-06-30 15:13       ` Dave Stevenson
2020-07-01  7:21         ` Laurent Pinchart
2020-06-23 16:55 ` [PATCH 23/25] media: ov5647: Support V4L2_CID_HBLANK control Jacopo Mondi
2020-06-23 16:55 ` [PATCH 24/25] media: ov5647: Support V4L2_CID_VBLANK control Jacopo Mondi
2020-06-23 16:55 ` [PATCH 25/25] media: ov5647: Advertise the correct exposure range Jacopo Mondi
2020-06-29 17:33 ` [PATCH 00/25] media: ov5647: Support RaspberryPi Camera Module v1 Dafna Hirschfeld
2020-06-29 18:08   ` Dafna Hirschfeld
2020-07-10 15:59 ` Dafna Hirschfeld
2020-07-14 12:48   ` Jacopo Mondi

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=887cd8b6-c82c-22b9-ce48-5881a8b51686@collabora.com \
    --to=dafna.hirschfeld@collabora.com \
    --cc=aford173@gmail.com \
    --cc=andrew_gabbasov@mentor.com \
    --cc=dave.stevenson@raspberrypi.com \
    --cc=dave.stevenson@raspberrypi.org \
    --cc=erosca@de.adit-jv.com \
    --cc=hugues.fruchet@st.com \
    --cc=jacopo@jmondi.org \
    --cc=libcamera-devel@lists.libcamera.org \
    --cc=linux-media@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=mripard@kernel.org \
    --cc=mrodin@de.adit-jv.com \
    --cc=roman.kovalivskyi@globallogic.com \
    --cc=sakari.ailus@linux.intel.com \
    --cc=sudipi@jp.adit-jv.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-Media Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-media/0 linux-media/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-media linux-media/ https://lore.kernel.org/linux-media \
		linux-media@vger.kernel.org
	public-inbox-index linux-media

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-media


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git