Re: [PATCH v3] media: i2c-polling: add i2c-polling driver

Matt Ranostay
2016-11-23T19:19:38Z

On Wed, Nov 23, 2016 at 8:30 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Hi Matt,
>
> Thank you for the patch.
>
> On Tuesday 22 Nov 2016 17:18:40 Matt Ranostay wrote:
>> There are several thermal sensors that only have a low-speed bus
>> interface but output valid video data. This patchset enables support
>> for the AMG88xx "Grid-Eye" sensor family.
>>
>> Cc: Attila Kinali <attila@kinali.ch>
>> Cc: Marek Vasut <marex@denx.de>
>> Cc: Luca Barbato <lu_zero@gentoo.org>
>> Signed-off-by: Matt Ranostay <matt@ranostay.consulting>
>> ---
>> Changes from v1:
>> * correct i2c_polling_remove() operations
>> * fixed delay calcuation in buffer_queue()
>> * add include linux/slab.h
>>
>> Changes from v2:
>> * fix build error due to typo in include of slab.h
>>
>> drivers/media/i2c/Kconfig | 8 +
>> drivers/media/i2c/Makefile | 1 +
>> drivers/media/i2c/i2c-polling.c | 469 +++++++++++++++++++++++++++++++++++++
>
> Just looking at the driver name I believe a rename is needed. i2c-polling is a
> very generic name and would mislead many people into thinking about an I2C
> subsystem core feature instead of a video driver. "video-i2c" is one option,
> I'm open to other ideas.
>
>> 3 files changed, 478 insertions(+)
>> create mode 100644 drivers/media/i2c/i2c-polling.c
>>
>> diff --git a/drivers/media/i2c/Kconfig b/drivers/media/i2c/Kconfig
>> index b31fa6fae009..d840e7be0036 100644
>> --- a/drivers/media/i2c/Kconfig
>> +++ b/drivers/media/i2c/Kconfig
>> @@ -768,6 +768,14 @@ config VIDEO_M52790
>>
>> To compile this driver as a module, choose M here: the
>> module will be called m52790.
>> +
>> +config VIDEO_I2C_POLLING
>> + tristate "I2C polling video support"
>> + depends on VIDEO_V4L2 && I2C
>> + select VIDEOBUF2_VMALLOC
>> + ---help---
>> + Enable the I2C polling video support which supports the following:
>> + * Panasonic AMG88xx Grid-Eye Sensors
>> endmenu
>>
>> menu "Sensors used on soc_camera driver"
>> diff --git a/drivers/media/i2c/Makefile b/drivers/media/i2c/Makefile
>> index 92773b2e6225..8182ec9f66b9 100644
>> --- a/drivers/media/i2c/Makefile
>> +++ b/drivers/media/i2c/Makefile
>> @@ -79,6 +79,7 @@ obj-$(CONFIG_VIDEO_LM3646) += lm3646.o
>> obj-$(CONFIG_VIDEO_SMIAPP_PLL) += smiapp-pll.o
>> obj-$(CONFIG_VIDEO_AK881X) += ak881x.o
>> obj-$(CONFIG_VIDEO_IR_I2C) += ir-kbd-i2c.o
>> +obj-$(CONFIG_VIDEO_I2C_POLLING) += i2c-polling.o
>> obj-$(CONFIG_VIDEO_ML86V7667) += ml86v7667.o
>> obj-$(CONFIG_VIDEO_OV2659) += ov2659.o
>> obj-$(CONFIG_VIDEO_TC358743) += tc358743.o
>> diff --git a/drivers/media/i2c/i2c-polling.c
>> b/drivers/media/i2c/i2c-polling.c new file mode 100644
>> index 000000000000..46a4eecde2d2
>> --- /dev/null
>> +++ b/drivers/media/i2c/i2c-polling.c
>> @@ -0,0 +1,469 @@
>> +/*
>> + * i2c_polling.c - Support for polling I2C video devices
>> + *
>> + * Copyright (C) 2016 Matt Ranostay <mranostay@ranostay.consulting>
>> + *
>> + * Based on the orginal work drivers/media/parport/bw-qcam.c
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; either version 2 of the License, or
>> + * (at your option) any later version.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * Supported:
>> + * - Panasonic AMG88xx Grid-Eye Sensors
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>
> I don't think you implement device tree support, is linux/of.h needed ? Or
> maybe you could implement device tree support ;-)
>
Indeed.

>> +#include <linux/delay.h>
>> +#include <linux/videodev2.h>
>> +#include <linux/mutex.h>
>> +#include <linux/slab.h>
>> +#include <linux/i2c.h>
>> +#include <media/v4l2-common.h>
>> +#include <media/v4l2-ioctl.h>
>> +#include <media/v4l2-device.h>
>> +#include <media/v4l2-fh.h>
>> +#include <media/v4l2-ctrls.h>
>> +#include <media/v4l2-event.h>
>
> You don't implement any control, you can drop support for control events as
> well.
>
>> +#include <media/videobuf2-vmalloc.h>
>
> Please sort includes alphabetically, it makes it easier to locate duplicates.
>
>> +#define I2C_POLLING_DRIVER "i2c-polling"
>> +
>> +struct i2c_polling_chip;
>> +
>> +struct i2c_polling_data {
>> + struct i2c_client *client;
>> + const struct i2c_polling_chip *chip;
>> + struct mutex lock;
>> + struct mutex queue_lock;
>> + unsigned int last_update;
>> +
>> + struct v4l2_device v4l2_dev;
>> + struct video_device vdev;
>> + struct vb2_queue vb_vidq;
>> +};
>> +
>> +static struct v4l2_fmtdesc amg88xx_format = {
>> + .description = "12-bit Greyscale",
>> + .pixelformat = V4L2_PIX_FMT_Y12,
>> +};
>> +
>> +static struct v4l2_frmsize_discrete amg88xx_size = {
>> + .width = 8,
>> + .height = 8,
>> +};
>> +
>> +struct i2c_polling_chip {
>> + /* video dimensions */
>> + struct v4l2_fmtdesc *format;
>> + struct v4l2_frmsize_discrete *size;
>> +
>> + /* max frames per second */
>> + unsigned int max_fps;
>> +
>> + /* pixel buffer size */
>> + unsigned int buffer_size;
>> +
>> + /* xfer function */
>> + int (*xfer)(struct i2c_polling_data *data, char *buf);
>> +};
>> +
>> +enum {
>> + AMG88XX = 0,
>> + I2C_POLLING_CHIP_CNT,
>> +};
>> +
>> +static int amg88xx_xfer(struct i2c_polling_data *data, char *buf)
>> +{
>> + struct i2c_client *client = data->client;
>> + struct i2c_msg msg[2];
>> + u8 reg = 0x80;
>> + int ret;
>> +
>> + msg[0].addr = client->addr;
>> + msg[0].flags = 0;
>> + msg[0].len = 1;
>> + msg[0].buf = (char *) &reg;
>> +
>> + msg[1].addr = client->addr;
>> + msg[1].flags = I2C_M_RD;
>> + msg[1].len = data->chip->buffer_size;
>> + msg[1].buf = (char *) buf;
>> +
>> + ret = i2c_transfer(client->adapter, msg, 2);
>> +
>> + return (ret == 2) ? 0 : -EIO;
>> +}
>> +
>> +static const struct i2c_polling_chip
>> i2c_polling_chips[I2C_POLLING_CHIP_CNT] = {
>> + [AMG88XX] = {
>> + .size = &amg88xx_size,
>> + .format = &amg88xx_format,
>> + .max_fps = 10,
>> + .buffer_size = 128,
>> + .xfer = &amg88xx_xfer,
>> + },
>> +};
>> +
>> +static const struct v4l2_file_operations i2c_polling_fops = {
>> + .owner = THIS_MODULE,
>> + .open = v4l2_fh_open,
>> + .release = vb2_fop_release,
>> + .poll = vb2_fop_poll,
>> + .unlocked_ioctl = video_ioctl2,
>> + .read = vb2_fop_read,
>> + .mmap = vb2_fop_mmap,
>> +};
>> +
>> +static int queue_setup(struct vb2_queue *vq,
>> + unsigned int *nbuffers, unsigned int *nplanes,
>> + unsigned int sizes[], struct device *alloc_devs[])
>> +{
>> + struct i2c_polling_data *data = vb2_get_drv_priv(vq);
>> +
>> + if (!(*nbuffers))
>> + *nbuffers = 3;
>> +
>> + *nplanes = 1;
>> + sizes[0] = data->chip->buffer_size;
>> +
>> + return 0;
>> +}
>> +
>> +static void buffer_queue(struct vb2_buffer *vb)
>> +{
>> + struct i2c_polling_data *data = vb2_get_drv_priv(vb->vb2_queue);
>> + unsigned int delay = 1000 / data->chip->max_fps;
>> + int delta;
>> +
>> + mutex_lock(&data->lock);
>> +
>> + delta = jiffies - data->last_update;
>> +
>> + if (delta < msecs_to_jiffies(delay)) {
>> + int tmp = (delay - jiffies_to_msecs(delta)) * 1000;
>> +
>> + usleep_range(tmp, tmp + 1000);
>> + }
>> + data->last_update = jiffies;
>> +
>> + mutex_unlock(&data->lock);
>> +
>> + vb2_buffer_done(vb, VB2_BUF_STATE_DONE);
>> +}
>> +
>> +static void buffer_finish(struct vb2_buffer *vb)
>> +{
>> + struct i2c_polling_data *data = vb2_get_drv_priv(vb->vb2_queue);
>> + void *vbuf = vb2_plane_vaddr(vb, 0);
>> + int size = vb2_plane_size(vb, 0);
>> + int ret;
>> +
>> + mutex_lock(&data->lock);
>> +
>> + ret = data->chip->xfer(data, vbuf);
>> + if (ret < 0)
>> + vb->state = VB2_BUF_STATE_ERROR;
>
> That's not nice, the status should be set through vb2_buffer_done().
>
> You can't transfer data in the buffer_queue handler is that function can't
> sleep. Instead, I'm wondering whether it would make sense to perform transfers
> in a workqueue, to making timings less dependent on userspace.

Ok will think of how to refactor this for a workqueue.

>
>> + mutex_unlock(&data->lock);
>> +
>> + vb->timestamp = ktime_get_ns();
>> + vb2_set_plane_payload(vb, 0, ret ? 0 : size);
>> +}
>> +
>> +static struct vb2_ops i2c_polling_video_qops = {
>> + .queue_setup = queue_setup,
>> + .buf_queue = buffer_queue,
>> + .buf_finish = buffer_finish,
>> + .wait_prepare = vb2_ops_wait_prepare,
>> + .wait_finish = vb2_ops_wait_finish,
>> +};
>> +
>> +static int i2c_polling_querycap(struct file *file, void *priv,
>> + struct v4l2_capability *vcap)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(file);
>> +
>> + strlcpy(vcap->driver, data->v4l2_dev.name, sizeof(vcap->driver));
>> + strlcpy(vcap->card, "I2C Polling Video", sizeof(vcap->card));
>> +
>> + strlcpy(vcap->bus_info, "I2C:i2c-polling", sizeof(vcap->bus_info));
>
> The bus_info field should contain information to locate the device in the
> system. It correctly starts with I2C:, but should then be followed by the I2C
> bus number and the device address.

Ok.
>
>> + vcap->device_caps = V4L2_CAP_VIDEO_CAPTURE |
>> + V4L2_CAP_READWRITE | V4L2_CAP_STREAMING;
>> + vcap->capabilities = vcap->device_caps | V4L2_CAP_DEVICE_CAPS;
>
> You can set device_caps in the video_device structure instead, the code will
> fill vcap->device_caps and vcap->capabilities for you.

Ok.
>
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_g_input(struct file *file, void *fh, unsigned int
>> *inp)
>> +{
>> + *inp = 0;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_s_input(struct file *file, void *fh, unsigned int
>> inp)
>> +{
>> + return (inp > 0) ? -EINVAL : 0;
>> +}
>> +
>> +static int i2c_polling_enum_input(struct file *file, void *fh,
>> + struct v4l2_input *vin)
>> +{
>> + if (vin->index > 0)
>> + return -EINVAL;
>> +
>> + strlcpy(vin->name, "Camera", sizeof(vin->name));
>> +
>> + vin->type = V4L2_INPUT_TYPE_CAMERA;
>> + vin->audioset = 0;
>> + vin->tuner = 0;
>> + vin->std = 0;
>> + vin->status = 0;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_enum_fmt_vid_cap(struct file *file, void *fh,
>> + struct v4l2_fmtdesc *fmt)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(file);
>> + enum v4l2_buf_type type = fmt->type;
>> +
>> + if (fmt->index > 0)
>> + return -EINVAL;
>> +
>> + *fmt = *data->chip->format;
>> + fmt->type = type;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_enum_framesizes(struct file *file, void *fh,
>> + struct v4l2_frmsizeenum *fsize)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(file);
>> + struct v4l2_frmsize_discrete *size = data->chip->size;
>> +
>> + /* currently only one frame size is allowed */
>> + if (fsize->index > 0)
>> + return -EINVAL;
>> +
>> + if (fsize->pixel_format != data->chip->format->pixelformat)
>> + return -EINVAL;
>> +
>> + fsize->type = V4L2_FRMSIZE_TYPE_DISCRETE;
>> + fsize->discrete.width = size->width;
>> + fsize->discrete.height = size->height;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_enum_frameintervals(struct file *file, void *priv,
>> + struct v4l2_frmivalenum *fe)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(file);
>> + struct v4l2_frmsize_discrete *size = data->chip->size;
>> +
>> + if (fe->index > 0)
>> + return -EINVAL;
>> +
>> + if ((fe->width != size->width) || (fe->height != size->height))
>> + return -EINVAL;
>
> No need for the extra inner parentheses.
>
>> +
>> + fe->type = V4L2_FRMIVAL_TYPE_DISCRETE;
>> + fe->discrete.numerator = 1;
>> + fe->discrete.denominator = data->chip->max_fps;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_try_fmt_vid_cap(struct file *file, void *fh,
>> + struct v4l2_format *fmt)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(file);
>> + struct v4l2_pix_format *pix = &fmt->fmt.pix;
>> + struct v4l2_frmsize_discrete *size = data->chip->size;
>> +
>> + pix->width = size->width;
>> + pix->height = size->height;
>> + pix->pixelformat = data->chip->format->pixelformat;
>> + pix->field = V4L2_FIELD_NONE;
>> + pix->bytesperline = pix->width * 2;
>> + pix->sizeimage = pix->width * pix->height * 2;
>
> The bytesperline and sizeimage values depend on the format. If you make the
> format chip-specific, the computation should be generic as well.
>
> It's very hard at this time to know how much genericity should be expected
> from similar sensors. Unless you have more information about that, I would be
> tempted to make a device-specific driver for now, and then refactor it later
> to support more devices if the need arises (and if possible in a clean way).

Ok makes sense. There are other sensors that are thermopile arrays,
will have to think about this for awhile.

>
>> + pix->colorspace = V4L2_COLORSPACE_SRGB;
>> + pix->priv = 0;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_fmt_vid_cap(struct file *file, void *fh,
>> + struct v4l2_format *fmt)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(file);
>> + int ret = i2c_polling_try_fmt_vid_cap(file, fh, fmt);
>> +
>> + if (ret < 0)
>> + return ret;
>> +
>> + if (vb2_is_busy(&data->vb_vidq))
>> + return -EBUSY;
>
> A get format operation should be allowed even if the queue is busy, only set
> format should return -EBUSY.
>
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_g_parm(struct file *filp, void *priv,
>> + struct v4l2_streamparm *parm)
>> +{
>> + struct i2c_polling_data *data = video_drvdata(filp);
>> +
>> + if (parm->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
>> + return -EINVAL;
>> +
>> + parm->parm.capture.readbuffers = 3;
>> + parm->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
>> + parm->parm.capture.timeperframe.numerator = 1;
>> + parm->parm.capture.timeperframe.denominator = data->chip->max_fps;
>> +
>> + return 0;
>> +}
>> +
>> +static int i2c_polling_s_parm(struct file *filp, void *priv,
>> + struct v4l2_streamparm *parm)
>> +{
>> + if (parm->type != V4L2_BUF_TYPE_VIDEO_CAPTURE)
>> + return -EINVAL;
>> +
>> + return i2c_polling_g_parm(filp, priv, parm);
>> +}
>> +
>> +static const struct v4l2_ioctl_ops i2c_polling_ioctl_ops = {
>> + .vidioc_querycap = i2c_polling_querycap,
>> + .vidioc_g_input = i2c_polling_g_input,
>> + .vidioc_s_input = i2c_polling_s_input,
>> + .vidioc_enum_input = i2c_polling_enum_input,
>> + .vidioc_enum_fmt_vid_cap = i2c_polling_enum_fmt_vid_cap,
>> + .vidioc_enum_framesizes = i2c_polling_enum_framesizes,
>> + .vidioc_enum_frameintervals = i2c_polling_enum_frameintervals,
>> + .vidioc_g_fmt_vid_cap = i2c_polling_fmt_vid_cap,
>> + .vidioc_s_fmt_vid_cap = i2c_polling_fmt_vid_cap,
>> + .vidioc_g_parm = i2c_polling_g_parm,
>> + .vidioc_s_parm = i2c_polling_s_parm,
>> + .vidioc_try_fmt_vid_cap = i2c_polling_try_fmt_vid_cap,
>> + .vidioc_reqbufs = vb2_ioctl_reqbufs,
>> + .vidioc_create_bufs = vb2_ioctl_create_bufs,
>> + .vidioc_prepare_buf = vb2_ioctl_prepare_buf,
>> + .vidioc_querybuf = vb2_ioctl_querybuf,
>> + .vidioc_qbuf = vb2_ioctl_qbuf,
>> + .vidioc_dqbuf = vb2_ioctl_dqbuf,
>> + .vidioc_streamon = vb2_ioctl_streamon,
>> + .vidioc_streamoff = vb2_ioctl_streamoff,
>
> No need to set the buffer-related .vidioc_* pointers to vb2_ioctl_*
> explicitly, the core will use vb2 if the fields are left unset.
>
>> + .vidioc_log_status = v4l2_ctrl_log_status,
>> + .vidioc_subscribe_event = v4l2_ctrl_subscribe_event,
>> + .vidioc_unsubscribe_event = v4l2_event_unsubscribe,
>> +};
>> +
>> +static int i2c_polling_probe(struct i2c_client *client,
>> + const struct i2c_device_id *id)
>> +{
>> + struct i2c_polling_data *data;
>> + struct v4l2_device *v4l2_dev;
>> + struct vb2_queue *queue;
>> + int ret;
>> +
>> + data = kzalloc(sizeof(*data), GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + data->chip = &i2c_polling_chips[id->driver_data];
>> + data->client = client;
>> + data->last_update = jiffies;
>> + v4l2_dev = &data->v4l2_dev;
>> + strlcpy(v4l2_dev->name, I2C_POLLING_DRIVER, sizeof(v4l2_dev->name));
>> +
>> + ret = v4l2_device_register(&client->dev, v4l2_dev);
>> + if (ret < 0)
>> + goto error_free_device;
>> +
>> + mutex_init(&data->lock);
>> + mutex_init(&data->queue_lock);
>> +
>> + queue = &data->vb_vidq;
>> + queue->type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>> + queue->io_modes = VB2_MMAP | VB2_USERPTR | VB2_READ;
>> + queue->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC;
>
> Please also set one of V4L2_BUF_FLAG_TSTAMP_SRC_SOF or
> V4L2_BUF_FLAG_TSTAMP_SRC_EOF.

Ok will do.
>
>> + queue->drv_priv = data;
>> + queue->ops = &i2c_polling_video_qops;
>> + queue->mem_ops = &vb2_vmalloc_memops;
>> +
>> + ret = vb2_queue_init(queue);
>> + if (ret < 0)
>> + goto error_free_device;
>> +
>> + data->vdev.queue = queue;
>> + data->vdev.queue->lock = &data->queue_lock;
>> +
>> + strlcpy(data->vdev.name, "I2C Polling Video", sizeof(data-
>>vdev.name));
>> +
>> + data->vdev.v4l2_dev = v4l2_dev;
>> + data->vdev.fops = &i2c_polling_fops;
>> + data->vdev.lock = &data->lock;
>> + data->vdev.ioctl_ops = &i2c_polling_ioctl_ops;
>> + data->vdev.release = video_device_release_empty;
>
> You should implement a release function and free the data structure there.
> Freeing data in the remove operation is a bad idea, as your driver will crash
> if the device is unbound from the driver during video streaming.
> Unregistration of the v4l2_device instance can also happen in the release
> callback. The video_device instance obviously has to be unregistered in the
> remove operation as done now.

Ok makes sense.
>
>> +
>> + video_set_drvdata(&data->vdev, data);
>> + i2c_set_clientdata(client, data);
>> +
>> + ret = video_register_device(&data->vdev, VFL_TYPE_GRABBER, -1);
>> + if (ret < 0)
>> + goto error_unregister_device;
>> +
>> + return 0;
>> +
>> +error_unregister_device:
>> + v4l2_device_unregister(v4l2_dev);
>> +
>> +error_free_device:
>> + kfree(data);
>> +
>> + return ret;
>> +}
>> +
>> +static int i2c_polling_remove(struct i2c_client *client)
>> +{
>> + struct i2c_polling_data *data = i2c_get_clientdata(client);
>> +
>> + v4l2_device_unregister(&data->v4l2_dev);
>> + video_unregister_device(&data->vdev);
>> + kfree(data);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct i2c_device_id i2c_polling_id_table[] = {
>> + { "amg88xx", AMG88XX },
>> + {}
>> +};
>> +MODULE_DEVICE_TABLE(i2c, i2c_polling_id_table);
>> +
>> +static struct i2c_driver i2c_polling_driver = {
>> + .driver = {
>> + .name = I2C_POLLING_DRIVER,
>> + },
>> + .probe = i2c_polling_probe,
>> + .remove = i2c_polling_remove,
>> + .id_table = i2c_polling_id_table,
>> +};
>> +
>> +module_i2c_driver(i2c_polling_driver);
>> +
>> +MODULE_AUTHOR("Matt Ranostay <mranostay@ranostay.consulting>");
>> +MODULE_DESCRIPTION("I2C polling video support");
>> +MODULE_LICENSE("GPL");
>
> --
> Regards,
>
> Laurent Pinchart
>