Root cause (verified against our exact IDF tree, not the community guess):
the "258" in "sdio_write_task: Failed to send data: 258" is NOT a timeout
(that is 263). 258 = 0x102 = ESP_ERR_INVALID_ARG. On the ESP32-P4, block-
mode CMD53 writes require the SOURCE buffer to be 64-byte (cache-line)
aligned; the IDF sdmmc driver rejects a misaligned source with INVALID_ARG
BEFORE any bus activity. esp_hosts write loop then declares "Unrecoverable
host sdio state" and reboots the whole P4. The audio TX payload is not
64-aligned, so streaming mic audio wedged on the very FIRST frame (which is
exactly what we saw: listening -> instant Failed to send -> reboot).
This also explains why buffer/queue/clock/retry tuning all did nothing: the
write never reached the bus. And why our symptom was instant, not after
~100 writes (the community block-mode-desync theory) — it is the first
misaligned buffer, every time.
Fix: vendored esp_hosted 2.12.11 as an editable local component (overrides
the registry copy) and bounce a misaligned TX payload through one aligned
DMA scratch buffer in hosted_sdio_write_block (port_esp_hosted_host_sdio.c).
TX is serialized by the bus lock so a single static bounce buffer is safe;
freed in hosted_sdio_deinit. Host-only change — no C6 reflash.
VERIFIED ON HARDWARE (autonomous self-test): 40s of continuous mic-audio
upstream streaming — the traffic that previously wedged on the first frame
— ran clean, zero timeouts, zero reboots. A guarded SDIO_TX_SELFTEST harness
is kept (compiled out) for future SDIO stress testing.
Credit: root cause + patch designed via multi-agent investigation; the
precise 258=INVALID_ARG decode (correcting the upstream community timeout
assumption) came from checking our actual esp_err.h.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
