From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794341794; b=fcwrA8yHoxKGEkuelReiGAL82x7jzvqjF2AfyO/X0Kl4+seGtSl9IVV4a27L/GvshP/p dU7vgKVXY2ekXOxTUJbqv1Y/iTcTkmYH4cytx8r6sE3DmXs07m4iRhrxtrZicydyv+8vu szughR3ypqA3CdLwC9qFNuIL95YIvXecq1sRQR9aJqqfqVN9hwImDtMPLOLv0buKI5Oe0 ko10aPT2IINGaPlTSDLAhj75xqODYdM3FNRCw7q11loKWJhpzP8rogHUerei1lDM6115J 3V610hp/khE+CQeq1O45LnVyLTrD4FdQvcfG+LeD264hfpdKjNTYo5yu80T53r8BetQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794341794; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=zO10wKAE4P82VZclOw8qx37lMoJGAPT0t+9u2mDLtvA=; b=Bap/x5NM4Kp4gE7mUtkFskB/gWs75m1UH3dVuOJatu6TSeleDl0plvJ0ncmslLwTUwcY wO3KsLv8mp/2g/Pzraz8C77P9jmg8vTFzqw33bHAg/46BhOfJLRB9qV6BK5in5oRdAJHH qJtxQ8PO0ZGGOxpj0WIcSJexcJaIBQZV//gNbaWfNkHNFoz2r9P4tt+AhrvVe1OFH298x AvKL/E0APLXo75HRv1pPBR1ynx0wqZaiMAOE+oFKeLKqEJVt2juAMjT3m/TQ5UjNe5nMs Th9JGmccppQPVMpW/5ZAM6G/MXvQnmTgEAXFxNDAuZW9gDRQc844+rCazsCchQtX7NA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=XCooIo3y; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A5986606A325 for ; Tue, 10 Nov 2026 20:16:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=XCooIo3y Received: by smtp.kernel.org (Postfix) with ESMTPSA id A67B21F008A5; Tue, 10 Nov 2026 20:16:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794341793; bh=zO10wKAE4P82VZclOw8qx37lMoJGAPT0t+9u2mDLtvA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=XCooIo3yHKZ9cRi4tpLrXW4WoU3rTfbj2vRJZdBDUS1b47S0JwDB1dv/3wz0AHyis ENcXb2eyCKfYRQulgbZsBlpXQx8PDg9qlJni06sPOjczkI7Cy9edP6+BuEsEbpOe5y Q7yWoWXw794M3ru+SpvQpSR1rblBIN0c5Y7X9iCQm8beDI1VcUvORc6ulLuqYcE7j6 lPvNz3VBEOYoaoYIlFMn10fR/GY85XtyfZ+77AGiOP3zxxvC9GR3oMDuMEy51JB3Tv 9QVymPW2nIS3m7lK7wfKblwhmhxnIgGykwN4uAHlfzMLGL488FDgi0oDd/dT2tVlaB YcaQv3xtfx4cg== From: Sasha Levin To: stable@vger.kernel.org Cc: Vladyslav Tymoshchuk , Srinivas Kandagatla , Mark Brown , Sasha Levin Subject: [PATCH 6.6.y] ASoC: qcom: q6apm-dai: wrap the position of a full ring to 0 Date: Tue, 10 Nov 2026 15:16:31 -0500 Message-ID: <20261110200604.3670083-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107053538-failed-6.6-0ea3e0b196f9@kernel.org> References: <20261107053538-failed-6.6-0ea3e0b196f9@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Vladyslav Tymoshchuk [ Upstream commit 0ea3e0b196f9dcc17b40ac881a6efef06459975b ] q6apm_dai_pointer() turns the number of period buffers the DSP has returned in the current lap, 1..periods, into a position and reports one frame less than that. Commit a93dad6f4e6a ("ASoC: q6apm-dai: make use of q6apm_get_hw_pointer") added the "- 1" so that the end of the ring is not reported as a position equal to the buffer size. One frame short has a cost once the application stops feeding the stream. The DSP returns the last queued buffer and the position stops at appl_ptr - 1, so avail stays at buffer_size - 1, below the default stop_threshold. The DSP sends nothing more as its queue is empty, so no period interrupt comes either: ALSA never detects the underrun and the stream stays RUNNING. A poll-driven application that missed its last wakeup waits forever, and drain only ends on its timeout, with -EIO. On capture, the last frame of each period is held back until the next one. Before that commit the position wrapped to 0 at the end of the ring. Do that again. A full lap is the start of the ring, and snd_pcm_update_hw_ptr0() accounts for the wrap: the position cannot move by more than one lap between two updates, as each returned buffer calls snd_pcm_period_elapsed() and the DSP holds at most periods buffers. Seen on a OnePlus Pad 3 (SM8750) with PipeWire in interrupt-driven scheduling: after a stall the PCM sat at hw_ptr 78239, appl_ptr 78240 (avail 3839 of 3840) for two hours. Fixes: a93dad6f4e6a ("ASoC: q6apm-dai: make use of q6apm_get_hw_pointer") Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-5-5 Signed-off-by: Vladyslav Tymoshchuk Reviewed-by: Srinivas Kandagatla Tested-by: Srinivas Kandagatla Link: https://patch.msgid.link/20261014162703.10172-2-tvlad744@gmail.com Signed-off-by: Mark Brown [ sashal: adjusted context in q6apm_dai_pointer() because the preceding bytes_to_frames() branch is absent ] Signed-off-by: Sasha Levin --- sound/soc/qcom/qdsp6/q6apm-dai.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/sound/soc/qcom/qdsp6/q6apm-dai.c b/sound/soc/qcom/qdsp6/q6apm-dai.c index 80df749859190..9e22269a8c723 100644 --- a/sound/soc/qcom/qdsp6/q6apm-dai.c +++ b/sound/soc/qcom/qdsp6/q6apm-dai.c @@ -440,11 +440,15 @@ static snd_pcm_uframes_t q6apm_dai_pointer(struct snd_soc_component *component, struct q6apm_dai_rtd *prtd = runtime->private_data; snd_pcm_uframes_t ptr; - ptr = q6apm_get_hw_pointer(prtd->graph, substream->stream) * runtime->period_size; - if (ptr) - return ptr - 1; + /* + * The hw pointer counts the period buffers the DSP has returned in + * this lap, 1..periods. A full lap is the start of the ring again: + * report 0 rather than one frame less, so that the position of a + * drained buffer reaches appl_ptr and ALSA sees the underrun. + */ + ptr = q6apm_get_hw_pointer(prtd->graph, substream->stream) % runtime->periods; - return 0; + return ptr * runtime->period_size; } static int q6apm_dai_hw_params(struct snd_soc_component *component, -- 2.53.0