Re: [PATCH 2/2] Added timers for dvb_ca_en50221_write_data

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Sun, 17 Sep 2017 03:27:22 +0200
"Jasmin J." <jasmin@anw.at> escreveu:

> From: Jasmin Jessich <jasmin@anw.at>
> 
> Some (older) CAMs are really slow in accepting data. The CI interface
> specification doesn't define a handshake for accepted data. Thus, the
> en50221 protocol driver can't control if a data byte has been correctly
> written to the CAM.
> 
> The current implementation writes the length and the data quick after
> each other. Thus, the slow CAMs may generate a WR error, which leads to
> the known error logging
>    "CAM tried to send a buffer larger than the ecount size".
> 
> To solve this issue the en50221 protocol driver needs to wait some CAM
> depending time between the different bytes to be written. Because the
> time is CAM dependent, an individual value per CAM needs to be set. For
> that SysFS is used in favor of ioctl's to allow the control of the timer
> values independent from any user space application.
> 
> This patch adds the timers and the SysFS nodes to set/get the timeout
> values and the timer waiting between the different steps of the CAM write
> access. A timer value of 0 (default) means "no timeout".

The patch series looks OK. However, I'm not seeing any documentation
patches explaining the new sysfs interface. I would be expecting an
update at linux DVB uAPI. Also, for all sysfs stuff, you need to add
it to Documentation/ABI/ using the format explained at its README.

Once you add it, I'll gladly apply it. Please add Ralph's ack on the
existing patches on your next submission.

Just a minor nitpick: on all patches, please prepend with "media: "
and the name of the part of the media subsystem that you're patching.

In this case, a good subject would be:

	media: dvb-core: add timers for dvb_ca_en50221_write_data

Regards,
Mauro

> 
> Signed-off-by: Jasmin Jessich <jasmin@anw.at>
> ---
>  drivers/media/dvb-core/dvb_ca_en50221.c | 132 +++++++++++++++++++++++++++++++-
>  1 file changed, 131 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c
> index 95b3723..50c4e45 100644
> --- a/drivers/media/dvb-core/dvb_ca_en50221.c
> +++ b/drivers/media/dvb-core/dvb_ca_en50221.c
> @@ -86,6 +86,13 @@ MODULE_PARM_DESC(cam_debug, "enable verbose debug messages");
>  #define DVB_CA_SLOTSTATE_WAITFR         6
>  #define DVB_CA_SLOTSTATE_LINKINIT       7
>  
> +enum dvb_ca_timers {
> +	DVB_CA_TIM_WR_HIGH  /* wait after writing length high */
> +,	DVB_CA_TIM_WR_LOW   /* wait after writing length low */
> +,	DVB_CA_TIM_WR_DATA  /* wait between data bytes */
> +,	DVB_CA_TIM_MAX
> +};
> +
>  /* Information on a CA slot */
>  struct dvb_ca_slot {
>  	/* current state of the CAM */
> @@ -119,6 +126,11 @@ struct dvb_ca_slot {
>  	unsigned long timeout;
>  };
>  
> +struct dvb_ca_timer {
> +	unsigned long min;
> +	unsigned long max;
> +};
> +
>  /* Private CA-interface information */
>  struct dvb_ca_private {
>  	struct kref refcount;
> @@ -161,6 +173,14 @@ struct dvb_ca_private {
>  
>  	/* mutex serializing ioctls */
>  	struct mutex ioctl_mutex;
> +
> +	struct dvb_ca_timer timers[DVB_CA_TIM_MAX];
> +};
> +
> +static const char dvb_ca_tim_names[DVB_CA_TIM_MAX][15] = {
> +	"tim_wr_high"
> +,	"tim_wr_low"
> +,	"tim_wr_data"
>  };
>  
>  static void dvb_ca_private_free(struct dvb_ca_private *ca)
> @@ -223,6 +243,14 @@ static char *findstr(char *haystack, int hlen, char *needle, int nlen)
>  	return NULL;
>  }
>  
> +static void dvb_ca_sleep(struct dvb_ca_private *ca, enum dvb_ca_timers tim)
> +{
> +	unsigned long min = ca->timers[tim].min;
> +
> +	if (min)
> +		usleep_range(min, ca->timers[tim].max);
> +}
> +
>  /* ************************************************************************** */
>  /* EN50221 physical interface functions */
>  
> @@ -868,10 +896,13 @@ static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot,
>  					    bytes_write >> 8);
>  	if (status)
>  		goto exit;
> +	dvb_ca_sleep(ca, DVB_CA_TIM_WR_HIGH);
> +
>  	status = ca->pub->write_cam_control(ca->pub, slot, CTRLIF_SIZE_LOW,
>  					    bytes_write & 0xff);
>  	if (status)
>  		goto exit;
> +	dvb_ca_sleep(ca, DVB_CA_TIM_WR_LOW);
>  
>  	/* send the buffer */
>  	for (i = 0; i < bytes_write; i++) {
> @@ -879,6 +910,7 @@ static int dvb_ca_en50221_write_data(struct dvb_ca_private *ca, int slot,
>  						    buf[i]);
>  		if (status)
>  			goto exit;
> +		dvb_ca_sleep(ca, DVB_CA_TIM_WR_DATA);
>  	}
>  
>  	/* check for write error (WE should now be 0) */
> @@ -1832,6 +1864,97 @@ static const struct dvb_device dvbdev_ca = {
>  };
>  
>  /* ************************************************************************** */
> +/* EN50221 device attributes (SysFS) */
> +
> +static int dvb_ca_tim_idx(struct dvb_ca_private *ca, const char *name)
> +{
> +	int tim_idx;
> +
> +	for (tim_idx = 0; tim_idx < DVB_CA_TIM_MAX; tim_idx++) {
> +		if (!strcmp(dvb_ca_tim_names[tim_idx], name))
> +			return tim_idx;
> +	}
> +	return -1;
> +}
> +
> +static ssize_t dvb_ca_tim_show(struct device *device,
> +			       struct device_attribute *attr, char *buf)
> +{
> +	struct dvb_device *dvbdev = dev_get_drvdata(device);
> +	struct dvb_ca_private *ca = dvbdev->priv;
> +	int tim_idx = dvb_ca_tim_idx(ca, attr->attr.name);
> +
> +	if (tim_idx < 0)
> +		return -ENXIO;
> +
> +	return sprintf(buf, "%ld\n", ca->timers[tim_idx].min);
> +}
> +
> +static ssize_t dvb_ca_tim_store(struct device *device,
> +				struct device_attribute *attr,
> +				const char *buf, size_t count)
> +{
> +	struct dvb_device *dvbdev = dev_get_drvdata(device);
> +	struct dvb_ca_private *ca = dvbdev->priv;
> +	int tim_idx = dvb_ca_tim_idx(ca, attr->attr.name);
> +	unsigned long min, max;
> +
> +	if (tim_idx < 0)
> +		return -ENXIO;
> +
> +	if (sscanf(buf, "%lu\n", &min) != 1)
> +		return -EINVAL;
> +
> +	/* value is in us; 100ms is a good maximum */
> +	if (min > (100 * USEC_PER_MSEC))
> +		return -EINVAL;
> +
> +	/* +10% (rounded up) */
> +	max = (min * 11 + 5) / 10;
> +	ca->timers[tim_idx].min = min;
> +	ca->timers[tim_idx].max = max;
> +
> +	return count;
> +}
> +
> +/* attribute definition with string pointer (see include/linux/sysfs.h) */
> +#define DVB_CA_ATTR(_name, _mode, _show, _store) {	\
> +	.attr = {.name = _name, .mode = _mode },	\
> +	.show	= _show,				\
> +	.store	= _store,				\
> +}
> +
> +#define DVB_CA_ATTR_TIM(_tim_idx)					\
> +	DVB_CA_ATTR(dvb_ca_tim_names[_tim_idx], 0664, dvb_ca_tim_show,	\
> +		    dvb_ca_tim_store)
> +
> +static const struct device_attribute dvb_ca_attrs[DVB_CA_TIM_MAX] = {
> +	DVB_CA_ATTR_TIM(DVB_CA_TIM_WR_HIGH)
> +,	DVB_CA_ATTR_TIM(DVB_CA_TIM_WR_LOW)
> +,	DVB_CA_ATTR_TIM(DVB_CA_TIM_WR_DATA)
> +};
> +
> +static int dvb_ca_device_attrs_add(struct dvb_ca_private *ca)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(dvb_ca_attrs); i++)
> +		if (device_create_file(ca->dvbdev->dev, &dvb_ca_attrs[i]))
> +			goto fail;
> +	return 0;
> +fail:
> +	return -1;
> +}
> +
> +static void ddb_device_attrs_del(struct dvb_ca_private *ca)
> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(dvb_ca_attrs); i++)
> +		device_remove_file(ca->dvbdev->dev, &dvb_ca_attrs[i]);
> +}
> +
> +/* ************************************************************************** */
>  /* Initialisation/shutdown functions */
>  
>  /**
> @@ -1901,6 +2024,10 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
>  		ret = -EINTR;
>  		goto unregister_device;
>  	}
> +
> +	if (dvb_ca_device_attrs_add(ca))
> +		goto unregister_device;
> +
>  	mb();
>  
>  	/* create a kthread for monitoring this CA device */
> @@ -1910,10 +2037,12 @@ int dvb_ca_en50221_init(struct dvb_adapter *dvb_adapter,
>  		ret = PTR_ERR(ca->thread);
>  		pr_err("dvb_ca_init: failed to start kernel_thread (%d)\n",
>  		       ret);
> -		goto unregister_device;
> +		goto delete_attrs;
>  	}
>  	return 0;
>  
> +delete_attrs:
> +	ddb_device_attrs_del(ca);
>  unregister_device:
>  	dvb_unregister_device(ca->dvbdev);
>  free_slot_info:
> @@ -1945,6 +2074,7 @@ void dvb_ca_en50221_release(struct dvb_ca_en50221 *pubca)
>  	for (i = 0; i < ca->slot_count; i++)
>  		dvb_ca_en50221_slot_shutdown(ca, i);
>  
> +	ddb_device_attrs_del(ca);
>  	dvb_remove_device(ca->dvbdev);
>  	dvb_ca_private_put(ca);
>  	pubca->private = NULL;



Thanks,
Mauro