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=1794340057; b=JkyxjCGrwXwcNxnbUEv27tGDw+RPB1E5z8hgb/gHsgfRy+/qf5aLJtJfGxH1LwQ2x+yt +ohRC9sJWxu9ScEh7K3d9uD9Osy9vQj0W2e47UDGIsj26+fXcK+gawGjJ6ooITvxVceJ1 QxE91jSlHl4Y1wVC1N7ZBh6BRO/5svGxmR/rUoEPDuj5mlKSADQGTUVHMuMijWGELL/uB C3rBZTbjYwogZjtQH8lPAzUY4B0k8KYDQODJGPksY/nAUujY2EdJdsWP6NpkS/+CNlSAG UeRLynMQn7KRJo6t+e2IlKQkrryehIUH7n2FAcYNd/WSiAqMdlbfECegu/QKHildwAQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794340057; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=YKzr0fOYEBbci2KWp2n/aI8Dz/rEuVkJrHN7HyC5L+Y=; b=ped/o1+wuQYlLGD/Q4tek8mdEYG4pynQV+plDPbDnFBXyzh+HewHqkZ6Pe20qxZcR44j KTNWgjzS6OntHBW2Xnn2TOQc6fxaNMf7Q1/dsCNhzSVoSnE8GsL6DLJqCDyuv5Iecm0Ez S5dORQRXaTd8ZglbRgwcWepE+zUoIKFzUAsNR4kKeERy7lddSDXSOBvbf5NveagsB9zze jHdvkjM2N1PkPSAyhb593hn6hHkbHkmg9qQvvPizQqWCJFlc5lrHjE0o6yQCD1XMDlXbI WUtuVKdcBxH3arugaMST3tFfm06DOu6IUDJSjPNs/BszJ5ciXNTJngBiXfqBOXyexVQ== 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=LhFCE52E; 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 AAEC0606A31C for ; Tue, 10 Nov 2026 19:47:36 +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=LhFCE52E Received: by smtp.kernel.org (Postfix) with ESMTPSA id C628E1F0089F; Tue, 10 Nov 2026 19:47:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794340056; bh=YKzr0fOYEBbci2KWp2n/aI8Dz/rEuVkJrHN7HyC5L+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LhFCE52EGGc6kEhop0asY6azpXoe2vWlc4CMuL9q4FDyq5Vp4D9sIQhmEobb6TyMq xWxgAusXDBayVD7X7g8ETU867SR9DO8W/vYlfUtGVScZCfhBgLogOWpaJuSzrcA9I/ +oryGLtJGiwfyRkv6aYG1nW8b/aU7DDYEHZTQk6Lwso0eViJfhrTxlGwIDan61Pl9q IRH4ok8LLqOfqo8HTRlg2gzSBEc5uC598h2RT06BfuNFwzP0RteNQpZ2augAMo7DmP wPl1HiYqcGMsplh7Jooynek06FXUZTQhRUQwLBvWoIhgEnppYzDDSRu2HgMrrdigMc Fnr6lb2XC0ZzA== From: Sasha Levin To: stable@vger.kernel.org Cc: Vladyslav Tymoshchuk , Srinivas Kandagatla , Mark Brown , Sasha Levin Subject: [PATCH 6.12.y] ASoC: qcom: q6apm-dai: wrap the position of a full ring to 0 Date: Tue, 10 Nov 2026 14:47:33 -0500 Message-ID: <20261110193643.3552101-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107052307-failed-6.12-0ea3e0b196f9@kernel.org> References: <20261107052307-failed-6.12-0ea3e0b196f9@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 3b00c6d5174ab..fef69e4318908 100644 --- a/sound/soc/qcom/qdsp6/q6apm-dai.c +++ b/sound/soc/qcom/qdsp6/q6apm-dai.c @@ -441,11 +441,15 @@ 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