drivers: video: wrap the CONFIG_POLL #ifdefs

[josuah]

Is your enhancement proposal related to a problem? Please describe.

Video drivers use k_polll_signal_raise() to communicate events, this is wrapped in #ifdef CONFIG_POLL.

zephyr/drivers/video/video_sw_generator.c

Lines 169 to 171 in c4ebf71

	if (IS_ENABLED(CONFIG_POLL) && data->signal) {
	k_poll_signal_raise(data->signal, VIDEO_BUF_DONE);
	}

zephyr/drivers/video/video_sw_generator.c

Lines 221 to 223 in c4ebf71

	if (IS_ENABLED(CONFIG_POLL) && data->signal) {
	k_poll_signal_raise(data->signal, VIDEO_BUF_ABORTED);
	}

zephyr/drivers/video/video_sw_generator.c

Lines 242 to 256 in c4ebf71

	#ifdef CONFIG_POLL
	static int video_sw_generator_set_signal(const struct device *dev, enum video_endpoint_id ep,
	struct k_poll_signal *signal)
	{
	struct video_sw_generator_data *data = dev->data;
	if (data->signal && signal != NULL) {
	return -EALREADY;
	}
	data->signal = signal;
	return 0;
	}
	#endif

zephyr/drivers/video/video_sw_generator.c

Lines 347 to 349 in c4ebf71

	#ifdef CONFIG_POLL
	.set_signal = video_sw_generator_set_signal,
	#endif

Describe the solution you'd like

Like I2C and SPI, add a wrapper around the k_poll_signal_raise() to avoid drivers to have to add #ifdef CONFIG_POLL every time:

zephyr/include/zephyr/drivers/i2c.h

Lines 967 to 1009 in c4ebf71

	#if defined(CONFIG_POLL) || defined(__DOXYGEN__)
	/** @cond INTERNAL_HIDDEN */
	void z_i2c_transfer_signal_cb(const struct device *dev, int result, void *userdata);
	/** @endcond */
	/**
	* @brief Perform data transfer to another I2C device in controller mode.
	*
	* This routine provides a generic interface to perform data transfer
	* to another I2C device asynchronously with a k_poll_signal completion.
	*
	* @see i2c_transfer_cb()
	* @funcprops \isr_ok
	*
	* @param dev Pointer to the device structure for an I2C controller
	* driver configured in controller mode.
	* @param msgs Array of messages to transfer, must live until callback completes.
	* @param num_msgs Number of messages to transfer.
	* @param addr Address of the I2C target device.
	* @param sig Signal to notify of transfer completion.
	*
	* @retval 0 If successful.
	* @retval -EIO General input / output error.
	* @retval -ENOSYS If transfer async is not implemented
	* @retval -EWOULDBLOCK If the device is temporarily busy doing another transfer
	*/
	static inline int i2c_transfer_signal(const struct device *dev,
	struct i2c_msg *msgs,
	uint8_t num_msgs,
	uint16_t addr,
	struct k_poll_signal *sig)
	{
	const struct i2c_driver_api *api = (const struct i2c_driver_api *)dev->api;
	if (api->transfer_cb == NULL) {
	return -ENOSYS;
	}
	return api->transfer_cb(dev, msgs, num_msgs, addr, z_i2c_transfer_signal_cb, sig);
	}
	#endif /* CONFIG_POLL */

zephyr/include/zephyr/drivers/spi.h

Lines 937 to 980 in c4ebf71

	#if defined(CONFIG_POLL) || defined(__DOXYGEN__)
	/** @cond INTERNAL_HIDDEN */
	void z_spi_transfer_signal_cb(const struct device *dev, int result, void *userdata);
	/** @endcond */
	/**
	* @brief Read/write the specified amount of data from the SPI driver.
	*
	* @note This function is asynchronous.
	*
	* @note This function is available only if @kconfig{CONFIG_SPI_ASYNC}
	* and @kconfig{CONFIG_POLL} are selected.
	*
	* @param dev Pointer to the device structure for the driver instance
	* @param config Pointer to a valid spi_config structure instance.
	* Pointer-comparison may be used to detect changes from
	* previous operations.
	* @param tx_bufs Buffer array where data to be sent originates from,
	* or NULL if none.
	* @param rx_bufs Buffer array where data to be read will be written to,
	* or NULL if none.
	* @param sig A pointer to a valid and ready to be signaled
	* struct k_poll_signal. (Note: if NULL this function will not
	* notify the end of the transaction, and whether it went
	* successfully or not).
	*
	* @retval frames Positive number of frames received in slave mode.
	* @retval 0 If successful in master mode.
	* @retval -errno Negative errno code on failure.
	*/
	static inline int spi_transceive_signal(const struct device *dev,
	const struct spi_config *config,
	const struct spi_buf_set *tx_bufs,
	const struct spi_buf_set *rx_bufs,
	struct k_poll_signal *sig)
	{
	const struct spi_driver_api *api =
	(const struct spi_driver_api *)dev->api;
	spi_callback_t cb = (sig == NULL) ? NULL : z_spi_transfer_signal_cb;
	return api->transceive_async(dev, config, tx_bufs, rx_bufs, cb, sig);
	}

Describe alternatives you've considered

Advise to keep struct k_poll_signal in the dev->data struct, allowing more lightweight idioms like (IF_ENABLED(CONFIG_POLL) && data->signal != NULL) instead of #ifdefs

zephyr/drivers/video/video_sw_generator.c

Lines 36 to 38 in c4ebf71

	bool ctrl_vflip;
	struct k_poll_signal *signal;
	uint32_t frame_rate;

Additional context

Example of extra work contributors would not need to do inside of #86915