[Linux-kernel-mentees] [PATCH v2 1/2] cec-follower: add tuner step increment/decrement

[hverkuil at xs4all.nl (Hans Verkuil)]

Hi Jiunn,

On 9/24/19 9:24 PM, Jiunn Chang wrote:
> Tuner step increment/decrement will select the next highest or next
> lowest service frequency.  There are a total of three possible
> frequencies from analog_freqs_khz given a broadcast type and system.
> 
> Opcodes implemented:
>   - <Tuner Step Increment>
>   - <Tuner Step Decrement>
> 
> Signed-off-by: Jiunn Chang <c0d1n61at3 at gmail.com>
> ---
>  utils/cec-follower/cec-tuner.cpp | 47 ++++++++++++++++++++++++++++++--
>  1 file changed, 44 insertions(+), 3 deletions(-)
> 
> diff --git a/utils/cec-follower/cec-tuner.cpp b/utils/cec-follower/cec-tuner.cpp
> index acc3fd00..1a9b9d90 100644
> --- a/utils/cec-follower/cec-tuner.cpp
> +++ b/utils/cec-follower/cec-tuner.cpp
> @@ -135,6 +135,22 @@ static bool analog_set_tuner_dev_info(struct node *node, struct cec_msg *msg)
>  	return false;
>  }
>  
> +static int analog_find_freq_index(struct cec_op_tuner_device_info *info)
> +{
> +	if (info->analog.ana_freq == 0)
> +		return -1;
> +
> +	int ana_freq_khz = (info->analog.ana_freq * 625) / 10;
> +
> +	for (int i = 0; i < NUM_ANALOG_FREQS; i++) {
> +		int freq = analog_freqs_khz[info->analog.ana_bcast_type][info->analog.bcast_system][i];
> +
> +		if (ana_freq_khz == freq)
> +			return i;
> +	}
> +	return -1;
> +}

Hmm, I don't like this code. I think that it would be cleaner to just add:

static unsigned int analog_freq_idx[3][9];

Which contains the index of the current frequency for each bcast_type/system
combination.

This ensures that 1) there always is a current frequency and 2) tuner stepping
is now trivial since all you need to do is to update the corresponding index.

Now, that said, I was thinking that it would be nice to have one bcast_type/system
combo with no channels at all, since that's a nice test as well.

I think that setting secam-lq for satellite to { 0, 0, 0 } to indicate no
defined channels would make a nice test case.

Something for a follow-up patch, though.

> +
>  void process_tuner_record_timer_msgs(struct node *node, struct cec_msg &msg, unsigned me)
>  {
>  	bool is_bcast = cec_msg_is_broadcast(&msg);
> @@ -178,12 +194,37 @@ void process_tuner_record_timer_msgs(struct node *node, struct cec_msg &msg, uns
>  		return;
>  
>  	case CEC_MSG_SELECT_DIGITAL_SERVICE:
> -	case CEC_MSG_TUNER_STEP_DECREMENT:
> -	case CEC_MSG_TUNER_STEP_INCREMENT:
> -		if (!cec_has_tuner(1 << me))
> +	case CEC_MSG_TUNER_STEP_DECREMENT: {
> +		if (!cec_has_tuner(1 << me) && !cec_has_tv(1 << me))
>  			break;
> +
> +		struct cec_op_tuner_device_info *info = &node->state.tuner_dev_info;
> +		int freq_idx = analog_find_freq_index(info);
> +		int idx = (freq_idx == 0) ? NUM_ANALOG_FREQS : freq_idx;
> +
> +		if (info->is_analog) {
> +			int freq = analog_freqs_khz[info->analog.ana_bcast_type][info->analog.bcast_system][--idx];
> +
> +			info->analog.ana_freq = (freq * 10) / 625;
> +		}
>  		return;
> +	}
> +
> +	case CEC_MSG_TUNER_STEP_INCREMENT: {
> +		if (!cec_has_tuner(1 << me) && !cec_has_tv(1 << me))
> +			break;
>  
> +		struct cec_op_tuner_device_info *info = &node->state.tuner_dev_info;
> +		int freq_idx = analog_find_freq_index(info);
> +		int idx = (freq_idx == NUM_ANALOG_FREQS - 1) ? -1 : freq_idx;
> +
> +		if (info->is_analog) {
> +			int freq = analog_freqs_khz[info->analog.ana_bcast_type][info->analog.bcast_system][++idx];
> +
> +			info->analog.ana_freq = (freq * 10) / 625;
> +		}
> +		return;
> +	}
>  
>  		/*
>  		  One Touch Record
> 

Regards,

	Hans