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Message-ID: <7905ecb9-6e18-4b3d-99ab-830aac19d3ad@kernel.org>
Date: Mon, 2 Jun 2025 11:58:16 +0200
From: Hans de Goede <hansg@...nel.org>
To: Ricardo Ribalda <ribalda@...omium.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Hans de Goede <hdegoede@...hat.com>,
Mauro Carvalho Chehab <mchehab@...nel.org>, Hans Verkuil <hverkuil@...all.nl>
Cc: linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
Hans Verkuil <hans@...erkuil.nl>
Subject: Re: [PATCH 7/9] media: uvcvideo: uvc_v4l2_unlocked_ioctl: Invert PM
logic
Hi Ricardo,
On 28-May-25 19:58, Ricardo Ribalda wrote:
> Instead of listing the IOCTLs that do not need to turn on the camera,
> list the IOCTLs that need to turn it on. This makes the code more
> maintainable.
>
> This patch is designed to be a NOP. Non relevant IOCTLs will be removed
> in future patches.
>
> Suggested-by: Hans Verkuil <hans@...erkuil.nl>
> Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
> ---
> drivers/media/usb/uvc/uvc_v4l2.c | 117 +++++++++++++++++++++++++++++++--------
> 1 file changed, 93 insertions(+), 24 deletions(-)
>
> diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
> index 2c6f3cf6bcc3f116bbdb3383d9af7d5be9832537..e7373a2ae3c37ca02f9076773154901a603820ac 100644
> --- a/drivers/media/usb/uvc/uvc_v4l2.c
> +++ b/drivers/media/usb/uvc/uvc_v4l2.c
> @@ -1264,42 +1264,111 @@ static long uvc_v4l2_compat_ioctl32(struct file *file,
> }
> #endif
>
> -static long uvc_v4l2_unlocked_ioctl(struct file *file,
> - unsigned int cmd, unsigned long arg)
> +static long uvc_v4l2_pm_ioctl(struct file *file,
> + unsigned int cmd, unsigned long arg)
> {
> struct uvc_fh *handle = file->private_data;
> int ret;
>
> - /* The following IOCTLs do not need to turn on the camera. */
> - switch (cmd) {
> - case VIDIOC_CREATE_BUFS:
> - case VIDIOC_DQBUF:
> - case VIDIOC_ENUM_FMT:
> - case VIDIOC_ENUM_FRAMEINTERVALS:
> - case VIDIOC_ENUM_FRAMESIZES:
> - case VIDIOC_ENUMINPUT:
> - case VIDIOC_EXPBUF:
> - case VIDIOC_G_FMT:
> - case VIDIOC_G_PARM:
> - case VIDIOC_G_SELECTION:
> - case VIDIOC_QBUF:
> - case VIDIOC_QUERYCAP:
> - case VIDIOC_REQBUFS:
> - case VIDIOC_SUBSCRIBE_EVENT:
> - case VIDIOC_UNSUBSCRIBE_EVENT:
> - return video_ioctl2(file, cmd, arg);
> - }
> -
> ret = uvc_pm_get(handle->stream->dev);
> if (ret)
> return ret;
> -
> ret = video_ioctl2(file, cmd, arg);
> -
> uvc_pm_put(handle->stream->dev);
> +
> return ret;
> }
>
> +static long uvc_v4l2_unlocked_ioctl(struct file *file,
> + unsigned int cmd, unsigned long arg)
> +{
> + /*
> + * For now, we do not support granular power saving for compat
> + * syscalls.
> + */
> + if (in_compat_syscall())
> + return uvc_v4l2_pm_ioctl(file, cmd, arg);
> +
> + /* The following IOCTLs do need to turn on the camera. */
> + switch (cmd) {
> + case UVCIOC_CTRL_MAP:
> + case UVCIOC_CTRL_QUERY:
> + case VIDIOC_CROPCAP:
> + case VIDIOC_DBG_G_CHIP_INFO:
> + case VIDIOC_DBG_G_REGISTER:
> + case VIDIOC_DBG_S_REGISTER:
> + case VIDIOC_DECODER_CMD:
> + case VIDIOC_DQEVENT:
> + case VIDIOC_DV_TIMINGS_CAP:
> + case VIDIOC_ENCODER_CMD:
> + case VIDIOC_ENUMAUDIO:
> + case VIDIOC_ENUMAUDOUT:
> + case VIDIOC_ENUMOUTPUT:
> + case VIDIOC_ENUMSTD:
> + case VIDIOC_ENUM_DV_TIMINGS:
> + case VIDIOC_ENUM_FREQ_BANDS:
> + case VIDIOC_G_AUDIO:
> + case VIDIOC_G_AUDOUT:
> + case VIDIOC_G_CROP:
> + case VIDIOC_G_CTRL:
> + case VIDIOC_G_DV_TIMINGS:
> + case VIDIOC_G_EDID:
> + case VIDIOC_G_ENC_INDEX:
> + case VIDIOC_G_EXT_CTRLS:
> + case VIDIOC_G_FBUF:
> + case VIDIOC_G_FREQUENCY:
> + case VIDIOC_G_INPUT:
> + case VIDIOC_G_JPEGCOMP:
> + case VIDIOC_G_MODULATOR:
> + case VIDIOC_G_OUTPUT:
> + case VIDIOC_G_PRIORITY:
> + case VIDIOC_G_SLICED_VBI_CAP:
> + case VIDIOC_G_STD:
> + case VIDIOC_G_TUNER:
> + case VIDIOC_LOG_STATUS:
> + case VIDIOC_OVERLAY:
> + case VIDIOC_PREPARE_BUF:
> + case VIDIOC_QUERYBUF:
> + case VIDIOC_QUERYCAP:
> + case VIDIOC_QUERYCTRL:
> + case VIDIOC_QUERYMENU:
> + case VIDIOC_QUERYSTD:
> + case VIDIOC_QUERY_DV_TIMINGS:
> + case VIDIOC_QUERY_EXT_CTRL:
> + case VIDIOC_REMOVE_BUFS:
> + case VIDIOC_STREAMOFF:
> + case VIDIOC_STREAMON:
> + case VIDIOC_S_AUDIO:
> + case VIDIOC_S_AUDOUT:
> + case VIDIOC_S_CROP:
> + case VIDIOC_S_CTRL:
> + case VIDIOC_S_DV_TIMINGS:
> + case VIDIOC_S_EDID:
> + case VIDIOC_S_EXT_CTRLS:
> + case VIDIOC_S_FBUF:
> + case VIDIOC_S_FMT:
> + case VIDIOC_S_FREQUENCY:
> + case VIDIOC_S_HW_FREQ_SEEK:
> + case VIDIOC_S_INPUT:
> + case VIDIOC_S_JPEGCOMP:
> + case VIDIOC_S_MODULATOR:
> + case VIDIOC_S_OUTPUT:
> + case VIDIOC_S_PARM:
> + case VIDIOC_S_PRIORITY:
> + case VIDIOC_S_SELECTION:
> + case VIDIOC_S_STD:
> + case VIDIOC_S_TUNER:
> + case VIDIOC_TRY_DECODER_CMD:
> + case VIDIOC_TRY_ENCODER_CMD:
> + case VIDIOC_TRY_EXT_CTRLS:
> + case VIDIOC_TRY_FMT:
> + return uvc_v4l2_pm_ioctl(file, cmd, arg);
> + }
IMHO adding a whole bunch of ioctls which are not supported by UVC at all here
and then dropping them again in patch 8/9 is not helpful.
I understand that your purpose is to have this initial patch
be a no-op, still doing the uvc_pm_get() + uvc_pm_put() for
unsupported IOCTLs but I don't really see that as something
useful to do while at the same time introducing unnecessary churn.
My preference would be to drop unsupported IOCTLs from this list
right away with a remark in the commit message that this changes
the behavior for unsupported IOCTLs.
For something like UVCIOC_CTRL_MAP I do agree that it is best
to keep it here and drop it later separately. Or maybe it would
be cleaner to add UVCIOC_CTRL_MAP to the list of IOCTLs _not_
needing pm before this patch ?
Regards,
Hans
> +
> + /* The other IOCTLs can run with the camera off. */
> + return video_ioctl2(file, cmd, arg);
> +}
> +
> const struct v4l2_ioctl_ops uvc_ioctl_ops = {
> .vidioc_g_fmt_vid_cap = uvc_ioctl_g_fmt,
> .vidioc_g_fmt_vid_out = uvc_ioctl_g_fmt,
>
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