Re: [PATCH v4] [DVB][FRONTEND] Added a new ioctl for optimizing frontend property set operation

Mauro Carvalho Chehab
2017-09-19T09:33:31Z

Em Mon, 18 Sep 2017 05:35:45 -0400
Satendra Singh Thakur <satendra.t@samsung.com> escreveu:

> Hello Mr Chehab,
> It seems that there is a mismatch among tab spacing
> in local patch on my PC, the patch in email
> and the patch in lkml site.
> This is causing alignment problem. Even if I fix alignment problem
> in my PC, alignment is different in lkml and email.
> Anyway, I have run checkpatch and got 0 err and warnings
> Please review it.
> Thanks for the patience.

Please, always put patch description here.

>
> Signed-off-by: Satendra Singh Thakur <satendra.t@samsung.com>
> ---

If you have any comments to maintainers/reviewers, add here,
after the "---" line.

> Documentation/media/uapi/dvb/fe-get-property.rst | 24 ++-
> drivers/media/dvb-core/dvb_frontend.c | 191 ++++++++++++++---------
> include/uapi/linux/dvb/frontend.h | 24 +++
> 3 files changed, 158 insertions(+), 81 deletions(-)
>
> diff --git a/Documentation/media/uapi/dvb/fe-get-property.rst b/Documentation/media/uapi/dvb/fe-get-property.rst
> index 015d4db..b63a588 100644
> --- a/Documentation/media/uapi/dvb/fe-get-property.rst
> +++ b/Documentation/media/uapi/dvb/fe-get-property.rst
> @@ -2,14 +2,14 @@
>
> .. _FE_GET_PROPERTY:
>
> -**************************************
> -ioctl FE_SET_PROPERTY, FE_GET_PROPERTY
> -**************************************
> +**************************************************************
> +ioctl FE_SET_PROPERTY, FE_GET_PROPERTY, FE_SET_PROPERTY_SHORT
> +**************************************************************
>
> Name
> ====
>
> -FE_SET_PROPERTY - FE_GET_PROPERTY - FE_SET_PROPERTY sets one or more frontend properties. - FE_GET_PROPERTY returns one or more frontend properties.
> +FE_SET_PROPERTY and FE_SET_PROPERTY_SHORT set one or more frontend properties. FE_GET_PROPERTY returns one or more frontend properties.
>
>
> Synopsis
> @@ -21,6 +21,8 @@ Synopsis
> .. c:function:: int ioctl( int fd, FE_SET_PROPERTY, struct dtv_properties *argp )
> :name: FE_SET_PROPERTY
>
> +.. c:function:: int ioctl( int fd, FE_SET_PROPERTY_SHORT, struct dtv_properties_short *argp )
> + :name: FE_SET_PROPERTY_SHORT
>
> Arguments
> =========
> @@ -29,15 +31,16 @@ Arguments
> File descriptor returned by :ref:`open() <frontend_f_open>`.
>
> ``argp``
> - pointer to struct :c:type:`dtv_properties`
> + Pointer to struct :c:type:`dtv_properties` or
> + struct :c:type:`dtv_properties_short`.
>
>
> Description
> ===========
>
> -All DVB frontend devices support the ``FE_SET_PROPERTY`` and
> -``FE_GET_PROPERTY`` ioctls. The supported properties and statistics
> -depends on the delivery system and on the device:
> +All DVB frontend devices support the ``FE_SET_PROPERTY``, ``FE_GET_PROPERTY``
> +and ``FE_SET_PROPERTY_SHORT`` ioctls. The supported properties and
> +statistics depends on the delivery system and on the device:
>
> - ``FE_SET_PROPERTY:``
>
> @@ -60,6 +63,11 @@ depends on the delivery system and on the device:
>
> - This call only requires read-only access to the device.
>
> +- ``FE_SET_PROPERTY_SHORT:``
> +
> + - This ioctl is similar to FE_SET_PROPERTY ioctl mentioned above
> + except that the arguments of the former utilize a struct :c:type:`dtv_property_short`
> + which is smaller in size.
>
> Return Value
> ============

I'm still in doubt about something: what's the real requirement from userspace
to justify a new ioctl?

Userspace will still need to allocate the same memory in order to get back
the tuner parameters with FE_GET_PROPERTY and to get statistics. Also, tuning
happens just once per channel, so hardly this would bring *any* real
performance improvement while tuning into a channel.

> diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c
> index e3fff8f..7c96197 100644
> --- a/drivers/media/dvb-core/dvb_frontend.c
> +++ b/drivers/media/dvb-core/dvb_frontend.c
> @@ -1081,28 +1081,25 @@ static struct dtv_cmds_h dtv_cmds[DTV_MAX_COMMAND + 1] = {
> _DTV_CMD(DTV_STAT_TOTAL_BLOCK_COUNT, 0, 0),
> };
>
> -static void dtv_property_dump(struct dvb_frontend *fe,
> - bool is_set,
> +static void dtv_get_property_dump(struct dvb_frontend *fe,
> struct dtv_property *tvp)
> {
> int i;
>
> if (tvp->cmd <= 0 || tvp->cmd > DTV_MAX_COMMAND) {
> - dev_warn(fe->dvb->device, "%s: %s tvp.cmd = 0x%08x undefined\n",
> - __func__,
> - is_set ? "SET" : "GET",
> - tvp->cmd);
> + dev_warn(fe->dvb->device, "%s: GET tvp.cmd = 0x%08x undefined\n"
> + , __func__,
> + tvp->cmd);
> return;
> }
>
> - dev_dbg(fe->dvb->device, "%s: %s tvp.cmd = 0x%08x (%s)\n", __func__,
> - is_set ? "SET" : "GET",
> - tvp->cmd,
> - dtv_cmds[tvp->cmd].name);
> + dev_dbg(fe->dvb->device, "%s: GET tvp.cmd = 0x%08x (%s)\n", __func__,
> + tvp->cmd,
> + dtv_cmds[tvp->cmd].name);
>
> if (dtv_cmds[tvp->cmd].buffer) {
> dev_dbg(fe->dvb->device, "%s: tvp.u.buffer.len = 0x%02x\n",
> - __func__, tvp->u.buffer.len);
> + __func__, tvp->u.buffer.len);
>
> for(i = 0; i < tvp->u.buffer.len; i++)
> dev_dbg(fe->dvb->device,
> @@ -1515,7 +1512,7 @@ static int dtv_property_process_get(struct dvb_frontend *fe,
> return r;
> }
>
> - dtv_property_dump(fe, false, tvp);
> + dtv_get_property_dump(fe, tvp);
>
> return 0;
> }
> @@ -1738,23 +1735,35 @@ static int dvbv3_set_delivery_system(struct dvb_frontend *fe)
> return emulate_delivery_system(fe, delsys);
> }
>
> +/**
> + * dtv_property_process_set - Sets a single DTV property
> + * @fe: Pointer to &struct dvb_frontend
> + * @file: Pointer to &struct file
> + * @cmd: Digital TV command
> + * @data: An unsigned 32-bits number
> + *
> + * This routine assigns the property
> + * value to the corresponding member of
> + * &struct dtv_frontend_properties
> + *
> + * Returns:
> + * Zero on success, negative errno on failure.
> + */
> static int dtv_property_process_set(struct dvb_frontend *fe,
> - struct dtv_property *tvp,
> - struct file *file)
> + struct file *file,
> + u32 cmd, u32 data)
> {
> int r = 0;
> struct dtv_frontend_properties *c = &fe->dtv_property_cache;
> -
> - /* Allow the frontend to validate incoming properties */
> - if (fe->ops.set_property) {
> - r = fe->ops.set_property(fe, tvp);
> - if (r < 0)
> - return r;
> - }
> -
> - dtv_property_dump(fe, true, tvp);
> -
> - switch(tvp->cmd) {
> + /** Dump DTV command name and value*/
> + if (!cmd || cmd > DTV_MAX_COMMAND)
> + dev_warn(fe->dvb->device, "%s: SET cmd 0x%08x undefined\n",
> + __func__, cmd);
> + else
> + dev_dbg(fe->dvb->device,
> + "%s: SET cmd 0x%08x (%s) to 0x%08x\n",
> + __func__, cmd, dtv_cmds[cmd].name, data);
> + switch (cmd) {
> case DTV_CLEAR:
> /*
> * Reset a cache of data specific to the frontend here. This does
> @@ -1767,140 +1776,140 @@ static int dtv_property_process_set(struct dvb_frontend *fe,
> * tunerequest so we can pass validation in the FE_SET_FRONTEND
> * ioctl.
> */
> - c->state = tvp->cmd;
> + c->state = cmd;
> dev_dbg(fe->dvb->device, "%s: Finalised property cache\n",
> __func__);
>
> r = dtv_set_frontend(fe);
> break;
> case DTV_FREQUENCY:
> - c->frequency = tvp->u.data;
> + c->frequency = data;
> break;
> case DTV_MODULATION:
> - c->modulation = tvp->u.data;
> + c->modulation = data;
> break;
> case DTV_BANDWIDTH_HZ:
> - c->bandwidth_hz = tvp->u.data;
> + c->bandwidth_hz = data;
> break;
> case DTV_INVERSION:
> - c->inversion = tvp->u.data;
> + c->inversion = data;
> break;
> case DTV_SYMBOL_RATE:
> - c->symbol_rate = tvp->u.data;
> + c->symbol_rate = data;
> break;
> case DTV_INNER_FEC:
> - c->fec_inner = tvp->u.data;
> + c->fec_inner = data;
> break;
> case DTV_PILOT:
> - c->pilot = tvp->u.data;
> + c->pilot = data;
> break;
> case DTV_ROLLOFF:
> - c->rolloff = tvp->u.data;
> + c->rolloff = data;
> break;
> case DTV_DELIVERY_SYSTEM:
> - r = dvbv5_set_delivery_system(fe, tvp->u.data);
> + r = dvbv5_set_delivery_system(fe, data);
> break;
> case DTV_VOLTAGE:
> - c->voltage = tvp->u.data;
> + c->voltage = data;
> r = dvb_frontend_ioctl_legacy(file, FE_SET_VOLTAGE,
> (void *)c->voltage);
> break;
> case DTV_TONE:
> - c->sectone = tvp->u.data;
> + c->sectone = data;
> r = dvb_frontend_ioctl_legacy(file, FE_SET_TONE,
> (void *)c->sectone);
> break;
> case DTV_CODE_RATE_HP:
> - c->code_rate_HP = tvp->u.data;
> + c->code_rate_HP = data;
> break;
> case DTV_CODE_RATE_LP:
> - c->code_rate_LP = tvp->u.data;
> + c->code_rate_LP = data;
> break;
> case DTV_GUARD_INTERVAL:
> - c->guard_interval = tvp->u.data;
> + c->guard_interval = data;
> break;
> case DTV_TRANSMISSION_MODE:
> - c->transmission_mode = tvp->u.data;
> + c->transmission_mode = data;
> break;
> case DTV_HIERARCHY:
> - c->hierarchy = tvp->u.data;
> + c->hierarchy = data;
> break;
> case DTV_INTERLEAVING:
> - c->interleaving = tvp->u.data;
> + c->interleaving = data;
> break;
>
> /* ISDB-T Support here */
> case DTV_ISDBT_PARTIAL_RECEPTION:
> - c->isdbt_partial_reception = tvp->u.data;
> + c->isdbt_partial_reception = data;
> break;
> case DTV_ISDBT_SOUND_BROADCASTING:
> - c->isdbt_sb_mode = tvp->u.data;
> + c->isdbt_sb_mode = data;
> break;
> case DTV_ISDBT_SB_SUBCHANNEL_ID:
> - c->isdbt_sb_subchannel = tvp->u.data;
> + c->isdbt_sb_subchannel = data;
> break;
> case DTV_ISDBT_SB_SEGMENT_IDX:
> - c->isdbt_sb_segment_idx = tvp->u.data;
> + c->isdbt_sb_segment_idx = data;
> break;
> case DTV_ISDBT_SB_SEGMENT_COUNT:
> - c->isdbt_sb_segment_count = tvp->u.data;
> + c->isdbt_sb_segment_count = data;
> break;
> case DTV_ISDBT_LAYER_ENABLED:
> - c->isdbt_layer_enabled = tvp->u.data;
> + c->isdbt_layer_enabled = data;
> break;
> case DTV_ISDBT_LAYERA_FEC:
> - c->layer[0].fec = tvp->u.data;
> + c->layer[0].fec = data;
> break;
> case DTV_ISDBT_LAYERA_MODULATION:
> - c->layer[0].modulation = tvp->u.data;
> + c->layer[0].modulation = data;
> break;
> case DTV_ISDBT_LAYERA_SEGMENT_COUNT:
> - c->layer[0].segment_count = tvp->u.data;
> + c->layer[0].segment_count = data;
> break;
> case DTV_ISDBT_LAYERA_TIME_INTERLEAVING:
> - c->layer[0].interleaving = tvp->u.data;
> + c->layer[0].interleaving = data;
> break;
> case DTV_ISDBT_LAYERB_FEC:
> - c->layer[1].fec = tvp->u.data;
> + c->layer[1].fec = data;
> break;
> case DTV_ISDBT_LAYERB_MODULATION:
> - c->layer[1].modulation = tvp->u.data;
> + c->layer[1].modulation = data;
> break;
> case DTV_ISDBT_LAYERB_SEGMENT_COUNT:
> - c->layer[1].segment_count = tvp->u.data;
> + c->layer[1].segment_count = data;
> break;
> case DTV_ISDBT_LAYERB_TIME_INTERLEAVING:
> - c->layer[1].interleaving = tvp->u.data;
> + c->layer[1].interleaving = data;
> break;
> case DTV_ISDBT_LAYERC_FEC:
> - c->layer[2].fec = tvp->u.data;
> + c->layer[2].fec = data;
> break;
> case DTV_ISDBT_LAYERC_MODULATION:
> - c->layer[2].modulation = tvp->u.data;
> + c->layer[2].modulation = data;
> break;
> case DTV_ISDBT_LAYERC_SEGMENT_COUNT:
> - c->layer[2].segment_count = tvp->u.data;
> + c->layer[2].segment_count = data;
> break;
> case DTV_ISDBT_LAYERC_TIME_INTERLEAVING:
> - c->layer[2].interleaving = tvp->u.data;
> + c->layer[2].interleaving = data;
> break;
>
> /* Multistream support */
> case DTV_STREAM_ID:
> case DTV_DVBT2_PLP_ID_LEGACY:
> - c->stream_id = tvp->u.data;
> + c->stream_id = data;
> break;
>
> /* ATSC-MH */
> case DTV_ATSCMH_PARADE_ID:
> - fe->dtv_property_cache.atscmh_parade_id = tvp->u.data;
> + fe->dtv_property_cache.atscmh_parade_id = data;
> break;
> case DTV_ATSCMH_RS_FRAME_ENSEMBLE:
> - fe->dtv_property_cache.atscmh_rs_frame_ensemble = tvp->u.data;
> + fe->dtv_property_cache.atscmh_rs_frame_ensemble = data;
> break;
>
> case DTV_LNA:
> - c->lna = tvp->u.data;
> + c->lna = data;
> if (fe->ops.set_lna)
> r = fe->ops.set_lna(fe);
> if (r < 0)
> @@ -1939,7 +1948,8 @@ static int dvb_frontend_ioctl(struct file *file,
> return -EPERM;
> }

The above optimization seem OK. Still, it is better to place it on
a separate patch.

>
> - if ((cmd == FE_SET_PROPERTY) || (cmd == FE_GET_PROPERTY))
> + if ((cmd == FE_SET_PROPERTY) || (cmd == FE_GET_PROPERTY)
> + || (cmd == FE_SET_PROPERTY_SHORT))
> err = dvb_frontend_ioctl_properties(file, cmd, parg);
> else {
> c->state = DTV_UNDEFINED;

Assuming that you provide a good reason why we need this ioctl, this
should be on the second patch with the new ioctl.

> @@ -1966,8 +1976,10 @@ static int dvb_frontend_ioctl_properties(struct file *file,
> dev_dbg(fe->dvb->device, "%s:\n", __func__);
>
> if (cmd == FE_SET_PROPERTY) {
> - dev_dbg(fe->dvb->device, "%s: properties.num = %d\n", __func__, tvps->num);
> - dev_dbg(fe->dvb->device, "%s: properties.props = %p\n", __func__, tvps->props);
> + dev_dbg(fe->dvb->device, "%s: properties.num = %d\n",
> + __func__, tvps->num);
> + dev_dbg(fe->dvb->device, "%s: properties.props = %p\n",
> + __func__, tvps->props);
>
> /* Put an arbitrary limit on the number of messages that can
> * be sent at once */
> @@ -1979,20 +1991,25 @@ static int dvb_frontend_ioctl_properties(struct file *file,
> return PTR_ERR(tvp);
>
> for (i = 0; i < tvps->num; i++) {
> - err = dtv_property_process_set(fe, tvp + i, file);
> + err = dtv_property_process_set(fe, file,
> + (tvp + i)->cmd,
> + (tvp + i)->u.data);
> if (err < 0)
> goto out;
> (tvp + i)->result = err;
> }
>
> if (c->state == DTV_TUNE)
> - dev_dbg(fe->dvb->device, "%s: Property cache is full, tuning\n", __func__);
> + dev_dbg(fe->dvb->device, "%s: Property cache is full, tuning\n",
> + __func__);
>
> } else if (cmd == FE_GET_PROPERTY) {
> struct dtv_frontend_properties getp = fe->dtv_property_cache;
>
> - dev_dbg(fe->dvb->device, "%s: properties.num = %d\n", __func__, tvps->num);
> - dev_dbg(fe->dvb->device, "%s: properties.props = %p\n", __func__, tvps->props);
> + dev_dbg(fe->dvb->device, "%s: properties.num = %d\n",
> + __func__, tvps->num);
> + dev_dbg(fe->dvb->device, "%s: properties.props = %p\n",
> + __func__, tvps->props);
>
> /* Put an arbitrary limit on the number of messages that can
> * be sent at once */
> @@ -2026,7 +2043,35 @@ static int dvb_frontend_ioctl_properties(struct file *file,
> err = -EFAULT;
> goto out;
> }

Indentation is still wrong. Are you setting tab to 8?

> -
> + /* New ioctl for optimizing property set*/
> + } else if (cmd == FE_SET_PROPERTY_SHORT) {
> + struct dtv_property_short *tvp_short = NULL;
> + struct dtv_properties_short *tvps_short = parg;
> +
> + dev_dbg(fe->dvb->device, "%s: properties.num = %d\n",
> + __func__, tvps_short->num);
> + dev_dbg(fe->dvb->device, "%s: properties.props = %p\n",
> + __func__, tvps_short->props);
> + if ((!tvps_short->num) ||
> + (tvps_short->num > DTV_IOCTL_MAX_MSGS))
> + return -EINVAL;
> + tvp_short = memdup_user(tvps_short->props,
> + tvps_short->num * sizeof(*tvp_short));
> + if (IS_ERR(tvp_short))
> + return PTR_ERR(tvp_short);
> + for (i = 0; i < tvps_short->num; i++) {
> + err = dtv_property_process_set(fe, file,
> + (tvp_short + i)->cmd,
> + (tvp_short + i)->data);
> + if (err < 0) {
> + kfree(tvp_short);
> + return err;
> + }
> + }
> + if (c->state == DTV_TUNE)
> + dev_dbg(fe->dvb->device, "%s: Property cache is full, tuning\n",
> + __func__);
> + kfree(tvp_short);

Place the new ioctl code on the second patch.

> } else
> err = -EOPNOTSUPP;
>
> diff --git a/include/uapi/linux/dvb/frontend.h b/include/uapi/linux/dvb/frontend.h
> index 00a20cd..9d96dab 100644
> --- a/include/uapi/linux/dvb/frontend.h
> +++ b/include/uapi/linux/dvb/frontend.h
> @@ -476,6 +476,17 @@ struct dtv_property {
> int result;
> } __attribute__ ((packed));
>
> +/**
> + * struct dtv_property_short - A shorter version of &struct dtv_property
> + *
> + * @cmd: Digital TV command.
> + * @data: An unsigned 32-bits number.
> + */
> +struct dtv_property_short {
> + __u32 cmd;
> + __u32 data;
> +};
> +
> /* num of properties cannot exceed DTV_IOCTL_MAX_MSGS per ioctl */
> #define DTV_IOCTL_MAX_MSGS 64
>
> @@ -484,6 +495,18 @@ struct dtv_properties {
> struct dtv_property *props;
> };
>
> +/**
> + * struct dtv_properties_short - A variant of &struct dtv_properties
> + * to support &struct dtv_property_short
> + *
> + * @num: Number of properties
> + * @props: Pointer to &struct dtv_property_short
> + */
> +struct dtv_properties_short {
> + __u32 num;
> + struct dtv_property_short *props;
> +};
> +
> #if defined(__DVB_CORE__) || !defined (__KERNEL__)
>
> /*
> @@ -565,6 +588,7 @@ struct dvb_frontend_event {
>
> #define FE_SET_PROPERTY _IOW('o', 82, struct dtv_properties)
> #define FE_GET_PROPERTY _IOR('o', 83, struct dtv_properties)
> +#define FE_SET_PROPERTY_SHORT _IOW('o', 84, struct dtv_properties_short)
>
> /**
> * When set, this flag will disable any zigzagging or other "normal" tuning

Place the new ioctl code on the second patch.

Thanks,
Mauro