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Message-ID: <1da32e17-5bc0-2bf1-c2b5-9dd55fc3c2da@xs4all.nl>
Date: Wed, 21 Feb 2018 08:37:48 +0100
From: Hans Verkuil <hverkuil@...all.nl>
To: Alexandre Courbot <acourbot@...omium.org>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>,
Laurent Pinchart <laurent.pinchart@...asonboard.com>,
Pawel Osciak <posciak@...omium.org>,
Marek Szyprowski <m.szyprowski@...sung.com>,
Tomasz Figa <tfiga@...omium.org>,
Sakari Ailus <sakari.ailus@...ux.intel.com>,
Gustavo Padovan <gustavo.padovan@...labora.com>,
Linux Media Mailing List <linux-media@...r.kernel.org>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFCv4 16/21] v4l2: video_device: support for creating requests
On 02/21/2018 07:01 AM, Alexandre Courbot wrote:
> On Wed, Feb 21, 2018 at 1:35 AM, Hans Verkuil <hverkuil@...all.nl> wrote:
>> On 02/20/2018 05:44 AM, Alexandre Courbot wrote:
>>> Add a new VIDIOC_NEW_REQUEST ioctl, which allows to instanciate requests
>>> on devices that support the request API. Requests created that way can
>>> only control the device they originate from, making them suitable for
>>> simple devices, but not complex pipelines.
>>>
>>> Signed-off-by: Alexandre Courbot <acourbot@...omium.org>
>>> ---
>>> Documentation/ioctl/ioctl-number.txt | 1 +
>>> drivers/media/v4l2-core/v4l2-dev.c | 2 ++
>>> drivers/media/v4l2-core/v4l2-ioctl.c | 25 +++++++++++++++++++++++++
>>> include/media/v4l2-dev.h | 2 ++
>>> include/uapi/linux/videodev2.h | 3 +++
>>> 5 files changed, 33 insertions(+)
>>>
>>> diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt
>>> index 6501389d55b9..afdc9ed255b0 100644
>>> --- a/Documentation/ioctl/ioctl-number.txt
>>> +++ b/Documentation/ioctl/ioctl-number.txt
>>> @@ -286,6 +286,7 @@ Code Seq#(hex) Include File Comments
>>> <mailto:oe@...t.de>
>>> 'z' 10-4F drivers/s390/crypto/zcrypt_api.h conflict!
>>> '|' 00-7F linux/media.h
>>> +'|' 80-9F linux/media-request.h
>>> 0x80 00-1F linux/fb.h
>>> 0x89 00-06 arch/x86/include/asm/sockios.h
>>> 0x89 0B-DF linux/sockios.h
>>
>> This ^^^^ doesn't belong in this patch.
>
> Do you mean we need a separate patch for this?
Yes.
I now also see why you started at 0x80. Let's keep that for now.
>
>>
>>> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
>>> index 0301fe426a43..062ebee5bffc 100644
>>> --- a/drivers/media/v4l2-core/v4l2-dev.c
>>> +++ b/drivers/media/v4l2-core/v4l2-dev.c
>>> @@ -559,6 +559,8 @@ static void determine_valid_ioctls(struct video_device *vdev)
>>> set_bit(_IOC_NR(VIDIOC_TRY_EXT_CTRLS), valid_ioctls);
>>> if (vdev->ctrl_handler || ops->vidioc_querymenu)
>>> set_bit(_IOC_NR(VIDIOC_QUERYMENU), valid_ioctls);
>>> + if (vdev->req_mgr)
>>> + set_bit(_IOC_NR(VIDIOC_NEW_REQUEST), valid_ioctls);
>>> SET_VALID_IOCTL(ops, VIDIOC_G_FREQUENCY, vidioc_g_frequency);
>>> SET_VALID_IOCTL(ops, VIDIOC_S_FREQUENCY, vidioc_s_frequency);
>>> SET_VALID_IOCTL(ops, VIDIOC_LOG_STATUS, vidioc_log_status);
>>> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
>>> index ab4968ea443f..a45fe078f8ae 100644
>>> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
>>> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
>>> @@ -21,6 +21,7 @@
>>>
>>> #include <linux/videodev2.h>
>>>
>>> +#include <media/media-request.h>
>>> #include <media/v4l2-common.h>
>>> #include <media/v4l2-ioctl.h>
>>> #include <media/v4l2-ctrls.h>
>>> @@ -842,6 +843,13 @@ static void v4l_print_freq_band(const void *arg, bool write_only)
>>> p->rangehigh, p->modulation);
>>> }
>>>
>>> +static void vidioc_print_new_request(const void *arg, bool write_only)
>>> +{
>>> + const struct media_request_new *new = arg;
>>> +
>>> + pr_cont("fd=0x%x\n", new->fd);
>>
>> I'd use %d since fds are typically shown as signed integers.
>
> Right.
>
>>
>>> +}
>>> +
>>> static void v4l_print_edid(const void *arg, bool write_only)
>>> {
>>> const struct v4l2_edid *p = arg;
>>> @@ -2486,6 +2494,22 @@ static int v4l_enum_freq_bands(const struct v4l2_ioctl_ops *ops,
>>> return -ENOTTY;
>>> }
>>>
>>> +static int vidioc_new_request(const struct v4l2_ioctl_ops *ops,
>>> + struct file *file, void *fh, void *arg)
>>> +{
>>> +#if IS_ENABLED(CONFIG_MEDIA_REQUEST_API)
>>> + struct media_request_new *new = arg;
>>> + struct video_device *vfd = video_devdata(file);
>>> +
>>> + if (!vfd->req_mgr)
>>> + return -ENOTTY;
>>> +
>>> + return media_request_ioctl_new(vfd->req_mgr, new);
>>> +#else
>>> + return -ENOTTY;
>>> +#endif
>>> +}
>>
>> You don't need the #ifdef's here. media_request_ioctl_new() will be stubbed if
>> CONFIG_MEDIA_REQUEST_API isn't set.
>
> Correct.
>
>>
>>> +
>>> struct v4l2_ioctl_info {
>>> unsigned int ioctl;
>>> u32 flags;
>>> @@ -2617,6 +2641,7 @@ static struct v4l2_ioctl_info v4l2_ioctls[] = {
>>> IOCTL_INFO_FNC(VIDIOC_ENUM_FREQ_BANDS, v4l_enum_freq_bands, v4l_print_freq_band, 0),
>>> IOCTL_INFO_FNC(VIDIOC_DBG_G_CHIP_INFO, v4l_dbg_g_chip_info, v4l_print_dbg_chip_info, INFO_FL_CLEAR(v4l2_dbg_chip_info, match)),
>>> IOCTL_INFO_FNC(VIDIOC_QUERY_EXT_CTRL, v4l_query_ext_ctrl, v4l_print_query_ext_ctrl, INFO_FL_CTRL | INFO_FL_CLEAR(v4l2_query_ext_ctrl, id)),
>>> + IOCTL_INFO_FNC(VIDIOC_NEW_REQUEST, vidioc_new_request, vidioc_print_new_request, 0),
>>> };
>>> #define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
>>>
>>> diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
>>> index 53f32022fabe..e6c4e10889bc 100644
>>> --- a/include/media/v4l2-dev.h
>>> +++ b/include/media/v4l2-dev.h
>>> @@ -209,6 +209,7 @@ struct v4l2_file_operations {
>>> * @entity: &struct media_entity
>>> * @intf_devnode: pointer to &struct media_intf_devnode
>>> * @pipe: &struct media_pipeline
>>> + * @req_mgr: request manager to use if this device supports creating requests
>>> * @fops: pointer to &struct v4l2_file_operations for the video device
>>> * @device_caps: device capabilities as used in v4l2_capabilities
>>> * @dev: &struct device for the video device
>>> @@ -251,6 +252,7 @@ struct video_device
>>> struct media_intf_devnode *intf_devnode;
>>> struct media_pipeline pipe;
>>> #endif
>>> + struct media_request_mgr *req_mgr;
>>> const struct v4l2_file_operations *fops;
>>>
>>> u32 device_caps;
>>> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
>>> index 91cfe0cbd5c5..35706204e81d 100644
>>> --- a/include/uapi/linux/videodev2.h
>>> +++ b/include/uapi/linux/videodev2.h
>>> @@ -63,6 +63,7 @@
>>> #include <linux/compiler.h>
>>> #include <linux/ioctl.h>
>>> #include <linux/types.h>
>>> +#include <linux/media-request.h>
>>> #include <linux/v4l2-common.h>
>>> #include <linux/v4l2-controls.h>
>>>
>>> @@ -2407,6 +2408,8 @@ struct v4l2_create_buffers {
>>>
>>> #define VIDIOC_QUERY_EXT_CTRL _IOWR('V', 103, struct v4l2_query_ext_ctrl)
>>>
>>> +#define VIDIOC_NEW_REQUEST _IOWR('V', 104, struct media_request_new)
>>
>> Hmm, I probably call this VIDIOC_CREATE_REQUEST (analogous to CREATE_BUFS).
>> Ditto struct media_create_request and MEDIA_IOC_CREATE_REQUEST.
>
> Agree, it is better to keep consistency somehow.
>
>>
>> I'm still not convinced this is the right approach (as opposed to using the media
>> device node). I plan to dig deeper into the data structures tomorrow morning.
>
> I see no reason why this would not work. This seems more elegant than
> relying on the media node for this, and also does not require pulling
> the whole media controller support just to use requests on a simple
> codec or m2m device.
>
> But of course, I may not be seeing everything. :)
>
> Thanks for the review!
> Alex.
>
Regards,
Hans
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