[RFC] soundwire: add runtime BPT support #5604
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We should get as much as bandwidth for the BPT stream. Signed-off-by: Bard Liao <[email protected]>
The DP0 (BPT) params are computed in sdw_compute_dp0_port_params(). We should exclude the BPT stream when calculating the audio streams. Signed-off-by: Bard Liao <[email protected]>
We just need to conunt the audio stream bandwidth and BRA stream will use the remaining bandwidth. Signed-off-by: Bard Liao <[email protected]>
colume The existing code assumes the column number will not change, but it could change if curr_dr_freq changes. Calculate the new column number before checking the bandwidth to make the checking be more accurate. Signed-off-by: Bard Liao <[email protected]>
To allow BPT and audio stream work simultaneously, we need to record the hstop of the BPT stream. And use column bpt_hstop + 1 to the last column for audio streams. No function changed since bus->bpt_hstop is set to bus->params.col - 1 for now. Will update bus->audio_stream_hstart in the follow up commit. Signed-off-by: Bard Liao <[email protected]>
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Pull request overview
This PR implements runtime BPT (Bulk Point-to-Point) stream support for SoundWire, enabling firmware downloads while audio streams are active. The changes calculate available columns in SoundWire frames and allocate them to BPT streams on a first-come, first-served basis, with a reservation of 2 columns for audio streams when possible.
Key changes:
- Modified bandwidth calculation to exclude BPT streams and use remaining available bandwidth
- Added
bpt_hstopfield to track BPT stream column allocation - Updated frame column allocation logic to dynamically reserve space for audio streams
Reviewed changes
Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.
| File | Description |
|---|---|
| include/linux/soundwire/sdw.h | Added bpt_hstop field to track BPT stream column boundaries |
| drivers/soundwire/stream.c | Excluded BPT streams from bandwidth calculations during prepare/deprepare |
| drivers/soundwire/intel_ace2x.c | Updated to use bpt_hstop instead of total columns for BPT buffer calculations |
| drivers/soundwire/generic_bandwidth_allocation.c | Implemented dynamic column allocation logic with BPT stream filtering and reservation |
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| * @stream_refcount: number of streams currently using this bus | ||
| * @btp_stream_refcount: number of BTP streams currently using this bus (should | ||
| * be zero or one, multiple streams per link is not supported). | ||
| * @bpt_hstop: The hstop of the BPT stream. |
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Inconsistent terminology: comment uses 'hstop' (without underscore) while field name is 'bpt_hstop' (with underscore). Also, line 986 above uses 'BTP' while this and line 989 use 'BPT'. The terminology should be consistent throughout.
Suggested change
| * @bpt_hstop: The hstop of the BPT stream. | |
| * @bpt_hstop: The bpt_hstop of the BTP stream. |
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BPT is the right terminology. Also hstop is a terminology of SoundWire. I will leave it as it is.
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Update bus->bpt_hstop to record the hstop of the BPT stream. And return -EAGAIN when there is no bandwidth for the BPT stream. Signed-off-by: Bard Liao <[email protected]>
When a BRA stream is running, we should subtract the columns that is used by the BRA stream in bandwidth calculation. Signed-off-by: Bard Liao <[email protected]>
Now the SoundWire BPT stream and the audio stream can share the SoundWire bus bandwidth. However, it is still not allowed to have more than 1 BPT stream running simultaneously. Signed-off-by: Bard Liao <[email protected]>
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The driver may want to use BPT stream to download the firmware while an audio stream is running. This series calculates the available columns in a SoundWire frame and use them for the BPT stream. The streams are on on a first-come, first-served basis but will reserve 2 columns for the audio stream if possible. That should apply to most cases.