Hi, > -----Original Message----- > From: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx> > Sent: 28 June 2023 22:41 > To: Golani, Mitulkumar Ajitkumar <mitulkumar.ajitkumar.golani@xxxxxxxxx> > Cc: Kai Vehmanen <kai.vehmanen@xxxxxxxxxxxxxxx>; Borah, Chaitanya > Kumar <chaitanya.kumar.borah@xxxxxxxxx>; intel- > gfx@xxxxxxxxxxxxxxxxxxxxx; jyri.sarha@xxxxxxxxxxxxxxx > Subject: RE: [RFC 2/3] drm/i915/display: Configure and initialize > HDMI audio capabilities > > Hi, > > On Mon, 26 Jun 2023, Golani, Mitulkumar Ajitkumar wrote: > > Let's say, with the obtained audio_req_bandwidth, if I encounter the > following combination: > > pipe_config->audio.max_channel = 8 and pipe_config- > >audio.max_frequency = "X" value. > > Now, let's assume my sink supports only 7 channels. In this case, with > > current implementation, pruning will be bypassed, and there is a > > possibility that the sink-supported channel multiplied by the sink- > supported rate exceeding the available blank bandwidth, but pruning didn't > occur. > > > > For this situation, I am considering adding an "else" part in > intel_audio_compute_eld. > > This "else" part would check if (sad_to_channels(sad) < crtc_state- > >audio.max_channel), for example, in the GLK case also. > > In that case, the channel would be fixed. > > > > So, if Channel * audio sample container size * (iterating from Max > > rate to Min rate) is less than max_audio_samples_per_second, I believe > we can eliminate the above mentioned situation. > > If the sink's supported channel is lower than > > pipe_config->audio.max_channel, we can get another chance to adjust the > rate based on the sink's maximum capability. > [...] > > now pruning will happen in 2 cases, > > > > 1. If pipe_config->audio.max_channel < sink's supported channels then > > prune as per obtained combination from, > intel_hdmi_audio_compute_config. > > 2. If pipe_config->audio.max_channel > sink's supported channels, but > > sink's supported channel * sink supported max rate * audio sample > container size exceeds the max_audio_samples_per_second then prune > with sink's supported channel and rate (which satisfy bandwidth condition. > range: in between Max to min). > > > > Please give your opinion. > > ack, I think this is sensible. The SAD filtering cannot be perfect as there can > be multiple ways to prune the config to get within bandwidth budget (as we > have three varibles for LPCM, channel count, sampling rate and also sample > depth). So given limited visibility, I'd say above approach sounds good. I'd > also proceed (in your step2) with limiting first the sampling rate and only > further limit channel count in second step. > > Br, Kai Thanks Kai, I will update changes with new revision. Regards, MItul
