Em Sat, 06 Sep 2014 05:09:55 +0300 Antti Palosaari <crope@xxxxxx> escreveu: > Moro! > > On 08/29/2014 01:45 PM, Akihiro TSUKADA wrote: > > moikka, > > > >> Start polling thread, which polls once per 2 sec or so, which reads RSSI > >> and writes value to struct dtv_frontend_properties. That it is, in my > >> understanding. Same for all those DVBv5 stats. Mauro knows better as he > >> designed that functionality. > > > > I understand that RSSI property should be set directly in the tuner driver, > > but I'm afraid that creating a kthread just for updating RSSI would be > > overkill and complicate matters. > > > > Would you give me an advice? >> Mauro > > Now I know that as I implement it. I added kthread and it works > correctly, just I though it is aimed to work. In my case signal strength > is reported by demod, not tuner, because there is some logic in firmware > to calculate it. > > Here is patches you would like to look as a example: > > af9033: implement DVBv5 statistic for signal strength > https://patchwork.linuxtv.org/patch/25748/ Actually, you don't need to add a separate kthread to collect the stats. The DVB frontend core already has a thread that calls the frontend status on every 3 seconds (the time can actually be different, depending on the value for fepriv->delay. So, if the device doesn't have any issues on getting stats on this period, it could just hook the DVBv5 stats logic at ops.read_status(). >From the last time I reviewed the code, the PT3 driver seems to be using this approach already at the demod. Getting this value at the tuner makes it a little more trickier, as you need to use some tuner callback to update the demod cache. The .get_rf_strength ops is meant to get the signal strength from the tuner, but it doesn't allow the tuner to return a value in dBm. It shouldn't be the demod's task to convert a raw value on a tuner client into dBm. After reading this thread and its comments, I think that the best would be to not add a new callback. Instead, change the implementation at the .get_rf_strength callback in a way that it will return an integer from 0 to 65535 that would represent a "percentage" level, where 100% means the maximum signal that the device can measure. Inside the tuner driver (mxl301rf), a call to .get_rf_strength will directly update the FE stats cache to reflect the signal measurements in dBm. So, from the bridge driver, it will just call .get_rf_strength() without using the returned results. If, latter, we use this tuner on some other configuration (for example, on an hybrid analog/digital or SDR/digital board), the V4L2 part will use the "percentage" level, as the V4L2 API doesn't support returning values in dBm. Regards, Mauro > af9033: implement DVBv5 statistic for CNR > https://patchwork.linuxtv.org/patch/25744/ > > af9033: implement DVBv5 stat block counters > https://patchwork.linuxtv.org/patch/25749/ > > af9033: implement DVBv5 post-Viterbi BER > https://patchwork.linuxtv.org/patch/25750/ > > regards > Antti > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
