Date:   Tue, 28 Jan 2020 21:59:23 -0800
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Helen Koike <helen.koike@...labora.com>,
        <thierry.reding@...il.com>, <jonathanh@...dia.com>,
        <frankc@...dia.com>, <hverkuil@...all.nl>
CC:     <linux-media@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-clk@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v1 4/5] media: tegra: Add Tegra Video input driver for
 Tegra210


On 1/28/20 6:11 PM, Sowjanya Komatineni wrote:
>
> On 1/28/20 5:05 PM, Helen Koike wrote:
>> External email: Use caution opening links or attachments
>>
>>
>> On 1/28/20 10:49 PM, Sowjanya Komatineni wrote:
>>> On 1/28/20 2:13 PM, Sowjanya Komatineni wrote:
>>>> On 1/28/20 1:45 PM, Helen Koike wrote:
>>>>> External email: Use caution opening links or attachments
>>>>>
>>>>>
>>>>> Hi Sowjanya,
>>>>>
>>>>> I just took a really quick look, I didn't check the driver in 
>>>>> deep, so just some small comments below.
>>>>>
>>>>> On 1/28/20 4:23 PM, Sowjanya Komatineni wrote:
>>>>>> Tegra210 contains a powerful Video Input (VI) hardware controller
>>>>>> which can support up to 6 MIPI CSI camera sensors.
>>>>>>
>>>>>> Each Tegra CSI port can be one-to-one mapped to VI channel and can
>>>>>> capture from an external camera sensor connected to CSI or from
>>>>>> built-in test pattern generator.
>>>>>>
>>>>>> Tegra210 supports built-in test pattern generator from CSI to VI.
>>>>>>
>>>>>> This patch adds a V4L2 media controller and capture driver support
>>>>>> for Tegra210 built-in CSI to VI test pattern generator.
>>>>>>
>>>>>> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
>>>>> Could you send us the output of media-ctl --print-dot ? So we can 
>>>>> view the media topology easily?
>>>> root@...ra-ubuntu:/home/ubuntu# ./media-ctl --print-dot
>>>> digraph board {
>>>>          rankdir=TB
>>>>          n00000001 [label="54080000.vi-output-0\n/dev/video0", 
>>>> shape=box, style=filled, fillcolor=yellow]
>>>>          n00000005 [label="54080000.vi-output-1\n/dev/video1", 
>>>> shape=box, style=filled, fillcolor=yellow]
>>>>          n00000009 [label="54080000.vi-output-2\n/dev/video2", 
>>>> shape=box, style=filled, fillcolor=yellow]
>>>>          n0000000d [label="54080000.vi-output-3\n/dev/video3", 
>>>> shape=box, style=filled, fillcolor=yellow]
>>>>          n00000011 [label="54080000.vi-output-4\n/dev/video4", 
>>>> shape=box, style=filled, fillcolor=yellow]
>>>>          n00000015 [label="54080000.vi-output-5\n/dev/video5", 
>>>> shape=box, style=filled, fillcolor=yellow]
>>>>          n00000019 [label="{{} | tpg-0 | {<port0> 0}}", 
>>>> shape=Mrecord, style=filled, fillcolor=green]
>>>>          n00000019:port0 -> n00000001
>>>>          n0000001d [label="{{} | tpg-1 | {<port0> 0}}", 
>>>> shape=Mrecord, style=filled, fillcolor=green]
>>>>          n0000001d:port0 -> n00000005
>>>>          n00000021 [label="{{} | tpg-2 | {<port0> 0}}", 
>>>> shape=Mrecord, style=filled, fillcolor=green]
>>>>          n00000021:port0 -> n00000009
>>>>          n00000025 [label="{{} | tpg-3 | {<port0> 0}}", 
>>>> shape=Mrecord, style=filled, fillcolor=green]
>>>>          n00000025:port0 -> n0000000d
>>>>          n00000029 [label="{{} | tpg-4 | {<port0> 0}}", 
>>>> shape=Mrecord, style=filled, fillcolor=green]
>>>>          n00000029:port0 -> n00000011
>>>>          n0000002d [label="{{} | tpg-5 | {<port0> 0}}", 
>>>> shape=Mrecord, style=filled, fillcolor=green]
>>>>          n0000002d:port0 -> n00000015
>>>> }
>>>>
>>>>>> --- diff --git a/drivers/staging/media/tegra/host1x-video.h 
>>>>>> b/drivers/staging/media/tegra/host1x-video.h
>>>>>> new file mode 100644
>>>>>> index 000000000000..84d28e6f4362
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/staging/media/tegra/host1x-video.h
>>>>>> @@ -0,0 +1,33 @@
>>>>>> +// SPDX-License-Identifier: GPL-2.0-only
>>>>>> +/*
>>>>>> + * Copyright (C) 2020 NVIDIA CORPORATION.  All rights reserved.
>>>>>> + */
>>>>>> +
>>>>>> +#ifndef HOST1X_VIDEO_H
>>>>>> +#define HOST1X_VIDEO_H 1
>>>>>> +
>>>>>> +#include <linux/host1x.h>
>>>>>> +
>>>>>> +#include <media/media-device.h>
>>>>>> +#include <media/media-entity.h>
>>>>>> +#include <media/v4l2-async.h>
>>>>>> +#include <media/v4l2-ctrls.h>
>>>>>> +#include <media/v4l2-device.h>
>>>>>> +#include <media/v4l2-dev.h>
>>>>>> +#include <media/videobuf2-v4l2.h>
>>>>>> +
>>>>>> +#include "tegra-vi.h"
>>>>>> +#include "csi.h"
>>>>>> +
>>>>>> +struct tegra_camera {
>>>>>> +     struct v4l2_device v4l2_dev;
>>>>>> +     struct media_device media_dev;
>>>>>> +     struct device *dev;
>>>>> You can use cam->media_dev.dev instead of having this pointer.
>>>>>
>>> Will fix in v2
>>>>>> +     struct tegra_vi *vi;
>>>>>> +     struct tegra_csi_device *csi;
>>>>>> +};
>>>>>> +
>>>>>> +
>>>>>> +#define to_tegra_channel(vdev) \
>>>>>> +     container_of(vdev, struct tegra_channel, video)
>>>>> Why not inline instead of define. Inlines has the advantage of 
>>>>> checking types.
>>> Will change in v2
>>>>>> +static int __tegra_channel_try_format(struct tegra_channel *chan,
>>>>>> +                                   struct v4l2_pix_format *pix,
>>>>>> +                                   const struct 
>>>>>> tegra_video_format **vfmt)
>>>>>> +{
>>>>>> +     const struct tegra_video_format *fmt_info;
>>>>>> +     struct v4l2_subdev *subdev;
>>>>>> +     struct v4l2_subdev_format fmt;
>>>>>> +     struct v4l2_subdev_pad_config *pad_cfg;
>>>>>> +
>>>>>> +     subdev = tegra_channel_get_remote_subdev(chan);
>>>>>> +     pad_cfg = v4l2_subdev_alloc_pad_config(subdev);
>>>>>> +     if (!pad_cfg)
>>>>>> +             return -ENOMEM;
>>>>>> +
>>>>>> +     /*
>>>>>> +      * Retrieve format information and select the default 
>>>>>> format if the
>>>>>> +      * requested format isn't supported.
>>>>>> +      */
>>>>>> +     fmt_info = tegra_core_get_format_by_fourcc(chan, 
>>>>>> pix->pixelformat);
>>>>>> +     if (!fmt_info) {
>>>>>> +             pix->pixelformat = chan->format.pixelformat;
>>>>>> +             pix->colorspace = chan->format.colorspace;
>>>>>> +             fmt_info = tegra_core_get_format_by_fourcc(chan,
>>>>>> + pix->pixelformat);
>>>>>> +     }
>>>>>> +
>>>>>> +     /* Change this when start adding interlace format support */
>>>>>> +     pix->field = V4L2_FIELD_NONE;
>>>>>> +     fmt.which = V4L2_SUBDEV_FORMAT_TRY;
>>>>>> +     fmt.pad = 0;
>>>>>> +     v4l2_fill_mbus_format(&fmt.format, pix, fmt_info->code);
>>>>>> +     v4l2_subdev_call(subdev, pad, set_fmt, pad_cfg, &fmt);
>>>>> As fas as I understand, entities formats should be independent, it 
>>>>> is up to link_validate
>>>>> to check formats between entities.
>>>>> The capture shouldn't change the format of the subdevice.
>>>>>
>>> Tegra Built-in TPG on CSI accepts specific TPG sizes and CSI is 
>>> source and VI is sink.
>>>
>>> link validation happens only for sink ends of the link.
>> And what is the problem with it being on the sink end?
>> You just need to implement custom link validation in 
>> tegra_csi_media_ops that also checks the format
>> between the capture and the subdevice, no? Unless I missunderstood 
>> something here (which is quite possible).
>>
>> Examples:
>> drivers/staging/media/rkisp1/rkisp1-capture.c - 
>> rkisp1_capture_link_validate()
>> drivers/media/pci/intel/ipu3/ipu3-cio2.c - cio2_video_link_validate()
>> drivers/media/platform/sunxi/sun6i-csi/sun6i_video.c - 
>> sun6i_video_link_validate()
>>
>> Regards,
>> Helen
>>
> But if we move subdevice side format/size check into its 
> link_validation, any incorrect image size set thru set-fmt-video will 
> be taken and get-fmt-video will also show same as it doesn't validate 
> formats/sizes supported by CSI subdev during this time. link 
> validation happens during pipeline start. So thought to prevent 
> accepting incorrect format/size during set-fmt-video/get-fmt-video.
>
> Other than this I don't see any issue moving it to link_validation.
>
link validation happens for all the links in the pipeline where both of 
the ends of the links are V4L2 sub-devices.

v4l2_subdev_link_validate calls sink pad link_validate.

This driver has currently TPG support only where CSI v4l2 subdevice is 
the source and VI is the sink video entity.


>
>>> So with CSI subdev set_fmt sets width/height to default incase if 
>>> width/height is not from one of the supported sizes.
>>>
>>>>>> +
>>>>>> +     v4l2_fill_pix_format(pix, &fmt.format);
>>>>>> +     tegra_channel_fmt_align(chan, &fmt_info->bpp, &pix->width, 
>>>>>> &pix->height,
>>>>>> + &pix->bytesperline);
>>>>>> +     pix->sizeimage = pix->bytesperline * pix->height;
>>>>>> +
>>>>>> +     if (vfmt)
>>>>>> +             *vfmt = fmt_info;
>>>>>> +
>>>>>> +     v4l2_subdev_free_pad_config(pad_cfg);
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int tegra_channel_try_format(struct file *file, void *fh,
>>>>>> +                                 struct v4l2_format *format)
>>>>>> +{
>>>>>> +     struct v4l2_fh *vfh = file->private_data;
>>>>>> +     struct tegra_channel *chan = to_tegra_channel(vfh->vdev);
>>>>>> +
>>>>>> +     return __tegra_channel_try_format(chan, &format->fmt.pix, 
>>>>>> NULL);
>>>>>> +}
>>>>>> +
>>>>>> +static int tegra_channel_set_format(struct file *file, void *fh,
>>>>>> +                                 struct v4l2_format *format)
>>>>>> +{
>>>>>> +     struct v4l2_fh *vfh = file->private_data;
>>>>>> +     struct tegra_channel *chan = to_tegra_channel(vfh->vdev);
>>>>>> +     const struct tegra_video_format *info;
>>>>>> +     int ret;
>>>>>> +     struct v4l2_subdev_format fmt;
>>>>>> +     struct v4l2_subdev *subdev;
>>>>>> +     struct v4l2_pix_format *pix = &format->fmt.pix;
>>>>>> +
>>>>>> +     if (vb2_is_busy(&chan->queue))
>>>>>> +             return -EBUSY;
>>>>>> +
>>>>>> +     /* get supported format by try_fmt */
>>>>>> +     ret = __tegra_channel_try_format(chan, pix, &info);
>>>>>> +     if (ret)
>>>>>> +             return ret;
>>>>>> +
>>>>>> +     subdev = tegra_channel_get_remote_subdev(chan);
>>>>>> +
>>>>>> +     fmt.which = V4L2_SUBDEV_FORMAT_ACTIVE;
>>>>>> +     fmt.pad = 0;
>>>>>> +     v4l2_fill_mbus_format(&fmt.format, pix, info->code);
>>>>>> +     v4l2_subdev_call(subdev, pad, set_fmt, NULL, &fmt);
>>>>> same here.
>>>>>
>>> Calling subdev set_fmt here for the same reason as explained above.
>>>>>> +
>>>>>> +     v4l2_fill_pix_format(pix, &fmt.format);
>>>>>> +     chan->format = *pix;
>>>>>> +     chan->fmtinfo = info;
>>>>>> +     tegra_channel_update_format(chan, pix->width,
>>>>>> +                                 pix->height, info->fourcc,
>>>>>> +                                 &info->bpp,
>>>>>> +                                 pix->bytesperline);
>>>>>> +     *pix = chan->format;
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int tegra_channel_enum_input(struct file *file, void *fh,
>>>>>> +                                 struct v4l2_input *inp)
>>>>>> +{
>>>>>> +     /* Currently driver supports internal TPG only */
>>>>>> +     if (inp->index != 0)
>>>>> just
>>>>> if (inp->index)
>>>>>
>>> Will update in v2
>>>>>> +             return -EINVAL;
>>>>>> +
>>>>>> +     inp->type = V4L2_INPUT_TYPE_CAMERA;
>>>>>> +     strscpy(inp->name, "Tegra TPG", sizeof(inp->name));
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +static const struct tegra_video_format tegra_default_format = {
>>>>>> +     /* RAW 10 */
>>>>>> +     TEGRA_VF_RAW10,
>>>>>> +     10,
>>>>>> +     MEDIA_BUS_FMT_SRGGB10_1X10,
>>>>>> +     {2, 1},
>>>>>> +     TEGRA_IMAGE_FORMAT_DEF,
>>>>>> +     TEGRA_IMAGE_DT_RAW10,
>>>>>> +     V4L2_PIX_FMT_SRGGB10,
>>>>>> +     "RGRG.. GBGB..",
>>>>> It would be more readable to do:
>>>>>
>>>>> .code = TEGRA_VF_RAW10,
>>>>> .width = 10,
>>>>> .code = MEDIA_BUS_FMT_SRGGB10_1X10,
>>>>>
>>>>> and so on
>>> Will update in v2
>>>>>> +};
>>>>>> +
>>>>>> +/*
>>>>>> + * Helper functions
>>>>>> + */
>>>>>> +
>>>>>> +/**
>>>>>> + * tegra_core_get_default_format - Get default format
>>>>>> + *
>>>>>> + * Return: pointer to the format where the default format needs
>>>>>> + * to be filled in.
>>>>>> + */
>>>>>> +const struct tegra_video_format 
>>>>>> *tegra_core_get_default_format(void)
>>>>>> +{
>>>>>> +     return &tegra_default_format;
>>>>>> +}
>>>>> This is only used in tegra-channel.c, why not to declare it there 
>>>>> as static?
>>>>>
>>> Will move all video format retrieval helper functions to 
>>> corresponding file as static in v2
>>>>>> + +static struct v4l2_frmsize_discrete tegra_csi_tpg_sizes[] = {
>>>>>> +     {1280, 720},
>>>>>> +     {1920, 1080},
>>>>>> +     {3840, 2160},
>>>>>> +};
>>>>>> +
>>>>>> +/*
>>>>>> + * V4L2 Subdevice Pad Operations
>>>>>> + */
>>>>>> +static int tegra_csi_get_format(struct v4l2_subdev *subdev,
>>>>>> +                             struct v4l2_subdev_pad_config *cfg,
>>>>>> +                             struct v4l2_subdev_format *fmt)
>>>>>> +{
>>>>>> +     struct tegra_csi_channel *csi_chan = to_csi_chan(subdev);
>>>>>> +
>>>>>> +     mutex_lock(&csi_chan->format_lock);
>>>>> Do you need this lock? I think there is already a serialization in 
>>>>> the ioctls in place (to be confirmed).
>>>>>
>>> This is on CSI v4l2 subdevice side during format updates
>>>>>> +     memcpy(fmt, &csi_chan->ports->format,
>>>>>> +            sizeof(struct v4l2_mbus_framefmt));
>>>>> I would prefer just:
>>>>> *fmt = *csi_chan->ports->format;
>>>>>
>>>>> I think it is easier to read IMHO.
>>>>> same in tegra_csi_set_format().
>>>>>
>>> Will fix in v2
>>>>>> + mutex_unlock(&csi_chan->format_lock);
>>>>>> +
>>>>>> +     return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static void tegra_csi_try_mbus_fmt(struct v4l2_subdev *subdev,
>>>>>> +                                struct v4l2_mbus_framefmt *mfmt)
>>>>>> +{
>>>>>> +     struct tegra_csi_channel *csi_chan = to_csi_chan(subdev);
>>>>>> +     struct tegra_csi_device *csi = csi_chan->csi;
>>>>>> +     const struct v4l2_frmsize_discrete *sizes;
>>>>>> +     int i, j;
>>>>> unsigned
>>>>>
>>> Will fix in v2
>>>>>> +
>>>>>> +     for (i = 0; i < ARRAY_SIZE(tegra_csi_tpg_fmts); i++) {
>>>>>> +             struct v4l2_mbus_framefmt *mbus_fmt = 
>>>>>> &tegra_csi_tpg_fmts[i];
>>>>>> +
>>>>>> +             if (mfmt->code == mbus_fmt->code) {
>>>>>> +                     for (j = 0; j < 
>>>>>> ARRAY_SIZE(tegra_csi_tpg_sizes); j++) {
>>>>>> +                             sizes = &tegra_csi_tpg_sizes[j];
>>>>>> +                             if (mfmt->width == sizes->width &&
>>>>>> +                                 mfmt->height == sizes->height) {
>>>>>> +                                     return;
>>>>>> +                             }
>>>>>> +                     }
>>>>>> +             }
>>>>>> +
>>>>>> +             dev_info(csi->dev, "using Tegra default RAW10 video 
>>>>>> format\n");
>>>>>> +     }
>>>>>> +
>>>>>> +     dev_info(csi->dev, "using Tegra default WIDTH X HEIGHT 
>>>>>> (1920x1080)\n");
>>>>>> +     memcpy(mfmt, tegra_csi_tpg_fmts, sizeof(struct 
>>>>>> v4l2_mbus_framefmt));
>>>>>> +}
>>>>>> +
>>>>>> +

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