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Wed, 11 Nov 2026 16:47:59 -0800 (PST) Received: from localhost.localdomain ([183.96.175.225]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b3b5b2eeffsm20672163c88.9.2026.11.11.16.47.56 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Wed, 11 Nov 2026 16:47:58 -0800 (PST) From: Joonho Lee To: linux-sound@vger.kernel.org Cc: tiwai@suse.com, perex@perex.cz, anton.yakovlev@opensynergy.com, mst@redhat.com, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, corbet@lwn.net, skhan@linuxfoundation.org, rdunlap@infradead.org, linux-doc@vger.kernel.org, Joonho Lee Subject: [PATCH v27 14/17] docs: describe virtio-sound capture options Date: Thu, 12 Nov 2026 09:47:01 +0900 Message-ID: <20261112004704.49758-15-mynameisjune111@gmail.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20261112004704.49758-1-mynameisjune111@gmail.com> References: <20261112004704.49758-1-mynameisjune111@gmail.com> X-Mailing-List: linux-kernel@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 Document request-owned capture in the ALSA configuration guide. Describe `capture_packed_status` as default-off, reading a packed trailer after returned data while the fixed status scatterlist remains the default. Describe default-off `capture_pause_restart`: pause uses STOP and RELEASE, then resume uses PREPARE and START; disabled mode uses STOP and START while retaining the prepared stream. Note that on MMU systems request buffers are vmalloc-backed and page-rounded individually. They remain allocated from hw_params through hw_free, and capture data is copied into the ALSA ring. Assisted-by: LLM Signed-off-by: Joonho Lee --- Documentation/admin-guide/kernel-parameters.txt | 14 +++++++++++++ Documentation/sound/alsa-configuration.rst | 25 +++++++++++++++++++++++ 2 files changed, 39 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -8344,6 +8344,20 @@ Can be used multiple times for multiple devices. + virtio_snd.capture_packed_status= [HW,ALSA] + Read an explicitly enabled packed status trailer after + the returned capture data. The fixed status scatterlist is + used by default. + Format: + Default: false. + + virtio_snd.capture_pause_restart= [HW,ALSA] + Stop and release the stream when pausing capture. On + resume, send PREPARE and START. If disabled, pause uses + STOP and START while retaining the prepared stream. + Format: + Default: false. + vga= [BOOT,X86-32] Select a particular video mode See Documentation/arch/x86/boot.rst and Documentation/admin-guide/svga.rst. diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst --- a/Documentation/sound/alsa-configuration.rst +++ b/Documentation/sound/alsa-configuration.rst @@ -2537,6 +2537,31 @@ This module supports multiple cards. +Module virtio-snd +----------------- + +Virtio-sound capture receives data into a separate request buffer for each +PCM period. The driver validates the responses and appends frame-aligned audio +to the ALSA ring in request order. Valid short responses are retained. Empty +responses are accepted only during bounded startup or for requests already in +flight at STOP or PAUSE. + +capture_packed_status + Read an explicitly enabled packed status trailer after returned capture + data. The fixed status scatterlist is used by default. + (default = false) + +capture_pause_restart + Stop and release capture on pause. Resume with PREPARE and START. When + disabled, pause uses STOP and START while retaining the prepared stream. + (default = false) + +On MMU systems, the request buffers are vmalloc-backed and page-rounded +individually. Allocator rounding can make total additional memory exceed the +ALSA ring size, especially with small periods. The request buffers remain +allocated from hw_params until hw_free. +Captured audio is copied from each request buffer into the ALSA ring. + Module snd-virtuoso -------------------