Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 4deea4cb authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

[media] dvb: document dvb_frontend_sleep_until() 



This function is used mainly at the DVB core, in order to provide
emulation for a legacy ioctl. The only current exception is
the stv0299 driver, with takes more than 8ms to switch voltage,
breaking the emulation for FE_DISHNETWORK_SEND_LEGACY_CMD.

Document that.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent 6747b394

drivers/media/dvb-core/dvb_frontend.c

+5 −4
Original line number Diff line number Diff line
@@ -891,10 +891,11 @@ static void dvb_frontend_stop(struct dvb_frontend *fe) 
}



/*

 * Sleep until gettimeofday() > waketime + add_usec

 * This needs to be as precise as possible, but as the delay is

 * usually between 2ms and 32ms, it is done using a scheduled msleep

 * followed by usleep (normally a busy-wait loop) for the remainder

 * Sleep for the amount of time given by add_usec parameter

 *

 * This needs to be as precise as possible, as it affects the detection of

 * the dish tone command at the satellite subsystem. The precision is improved

 * by using a scheduled msleep followed by udelay for the remainder.

 */

void dvb_frontend_sleep_until(ktime_t *waketime, u32 add_usec)

{

drivers/media/dvb-core/dvb_frontend.h

+29 −1
Original line number Diff line number Diff line
@@ -404,6 +404,11 @@ struct dtv_frontend_properties; 
 *			FE_ENABLE_HIGH_LNB_VOLTAGE ioctl (only Satellite).

 * @dishnetwork_send_legacy_command: callback function to implement the

 *			FE_DISHNETWORK_SEND_LEGACY_CMD ioctl (only Satellite).

 *			Drivers should not use this, except when the DVB

 *			core emulation fails to provide proper support (e.g.

 *			if set_voltage() takes more than 8ms to work), and

 *			when backward compatibility with this legacy API is

 *			required.

 * @i2c_gate_ctrl:	controls the I2C gate. Newer drivers should use I2C

 *			mux support instead.

 * @ts_bus_ctrl:	callback function used to take control of the TS bus.
@@ -693,6 +698,29 @@ extern void dvb_frontend_reinitialise(struct dvb_frontend *fe); 
extern int dvb_frontend_suspend(struct dvb_frontend *fe);

extern int dvb_frontend_resume(struct dvb_frontend *fe);



extern void dvb_frontend_sleep_until(ktime_t *waketime, u32 add_usec);

/**

 * dvb_frontend_sleep_until() - Sleep for the amount of time given by

 *                      add_usec parameter

 *

 * @waketime: pointer to a struct ktime_t

 * @add_usec: time to sleep, in microseconds

 *

 * This function is used to measure the time required for the

 * %FE_DISHNETWORK_SEND_LEGACY_CMD ioctl to work. It needs to be as precise

 * as possible, as it affects the detection of the dish tone command at the

 * satellite subsystem.

 *

 * Its used internally by the DVB frontend core, in order to emulate

 * %FE_DISHNETWORK_SEND_LEGACY_CMD using the &dvb_frontend_ops.set_voltage()

 * callback.

 *

 * NOTE: it should not be used at the drivers, as the emulation for the

 * legacy callback is provided by the Kernel. The only situation where this

 * should be at the drivers is when there are some bugs at the hardware that

 * would prevent the core emulation to work. On such cases, the driver would

 * be writing a &dvb_frontend_ops.dishnetwork_send_legacy_command() and

 * calling this function directly.

 */

void dvb_frontend_sleep_until(ktime_t *waketime, u32 add_usec);



#endif