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{ "id": 26691, "url": "https://patchwork.libcamera.org/api/patches/26691/?format=api", "web_url": "https://patchwork.libcamera.org/patch/26691/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/projects/1/?format=api", "name": "libcamera", "link_name": "libcamera", "list_id": "libcamera_core", "list_email": "libcamera-devel@lists.libcamera.org", "web_url": "", "scm_url": "", "webscm_url": "" }, "msgid": "<20260508130804.8238-2-david.plowman@raspberrypi.com>", "date": "2026-05-08T12:57:41", "name": "[v5,1/3] pipeline: rpi: Simplify delayed controls", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": false, "hash": "118d6df606795b38292c25a09b55b1d06020b47c", "submitter": { "id": 42, "url": "https://patchwork.libcamera.org/api/people/42/?format=api", "name": "David Plowman", "email": "david.plowman@raspberrypi.com" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/26691/mbox/", "series": [ { "id": 5924, "url": "https://patchwork.libcamera.org/api/series/5924/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=5924", "date": "2026-05-08T12:57:40", "name": "Atomic control lists on Raspberry Pi", "version": 5, "mbox": "https://patchwork.libcamera.org/series/5924/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/26691/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/26691/checks/", "tags": {}, "headers": { "Return-Path": "<libcamera-devel-bounces@lists.libcamera.org>", "X-Original-To": "parsemail@patchwork.libcamera.org", "Delivered-To": "parsemail@patchwork.libcamera.org", "Received": [ "from lancelot.ideasonboard.com (lancelot.ideasonboard.com\n\t[92.243.16.209])\n\tby patchwork.libcamera.org (Postfix) with ESMTPS id D5796BDCBD\n\tfor <parsemail@patchwork.libcamera.org>;\n\tFri, 8 May 2026 13:08:11 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 1D26F6301A;\n\tFri, 8 May 2026 15:08:10 +0200 (CEST)", "from mail-wm1-x334.google.com (mail-wm1-x334.google.com\n\t[IPv6:2a00:1450:4864:20::334])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id B67DD62FE1\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tFri, 8 May 2026 15:08:07 +0200 (CEST)", "by mail-wm1-x334.google.com with SMTP id\n\t5b1f17b1804b1-48a7fe4f40bso21547685e9.0\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tFri, 08 May 2026 06:08:07 -0700 (PDT)", "from localhost.localdomain ([2a06:61c0:f337:0:9c1f:b517:931a:3b19])\n\tby smtp.gmail.com with ESMTPSA id\n\t5b1f17b1804b1-48e68f5d9b5sm34044905e9.15.2026.05.08.06.08.06\n\t(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n\tFri, 08 May 2026 06:08:06 -0700 (PDT)" ], "Authentication-Results": "lancelot.ideasonboard.com; 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\n\tFri, 08 May 2026 06:08:06 -0700 (PDT)", "From": "David Plowman <david.plowman@raspberrypi.com>", "To": "libcamera-devel@lists.libcamera.org", "Cc": "David Plowman <david.plowman@raspberrypi.com>,\n\tNaushir Patuck <naush@raspberrypi.com>,\n\tJacopo Mondi <jacopo.mondi@ideasonboard.com>", "Subject": "[PATCH v5 1/3] pipeline: rpi: Simplify delayed controls", "Date": "Fri, 8 May 2026 13:57:41 +0100", "Message-ID": "<20260508130804.8238-2-david.plowman@raspberrypi.com>", "X-Mailer": "git-send-email 2.47.3", "In-Reply-To": "<20260508130804.8238-1-david.plowman@raspberrypi.com>", "References": "<20260508130804.8238-1-david.plowman@raspberrypi.com>", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "X-BeenThere": "libcamera-devel@lists.libcamera.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<libcamera-devel.lists.libcamera.org>", "List-Unsubscribe": "<https://lists.libcamera.org/options/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=unsubscribe>", "List-Archive": "<https://lists.libcamera.org/pipermail/libcamera-devel/>", "List-Post": "<mailto:libcamera-devel@lists.libcamera.org>", "List-Help": "<mailto:libcamera-devel-request@lists.libcamera.org?subject=help>", "List-Subscribe": "<https://lists.libcamera.org/listinfo/libcamera-devel>,\n\t<mailto:libcamera-devel-request@lists.libcamera.org?subject=subscribe>", "Errors-To": "libcamera-devel-bounces@lists.libcamera.org", "Sender": "\"libcamera-devel\" <libcamera-devel-bounces@lists.libcamera.org>" }, "content": "The queueCount_ value is redundant and can be removed.\n\nThe pipeline handler calls the push and applyControls functions in a\nan interleaved manner, so queueCount_ was merely tracking writeCount_,\nand is therefore unnecessary.\n\nSigned-off-by: David Plowman <david.plowman@raspberrypi.com>\nReviewed-by: Naushir Patuck <naush@raspberrypi.com>\nReviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>\n---\n .../pipeline/rpi/common/delayed_controls.cpp | 62 +++++++++++--------\n .../pipeline/rpi/common/delayed_controls.h | 1 -\n 2 files changed, 36 insertions(+), 27 deletions(-)", "diff": "diff --git a/src/libcamera/pipeline/rpi/common/delayed_controls.cpp b/src/libcamera/pipeline/rpi/common/delayed_controls.cpp\nindex 19c71946..b647174f 100644\n--- a/src/libcamera/pipeline/rpi/common/delayed_controls.cpp\n+++ b/src/libcamera/pipeline/rpi/common/delayed_controls.cpp\n@@ -32,14 +32,15 @@ namespace RPi {\n *\n * Some sensor controls take effect with a delay as the sensor needs time to\n * adjust, for example exposure and analog gain. This is a helper class to deal\n- * with such controls and the intended users are pipeline handlers.\n+ * with such controls.\n *\n- * The idea is to extend the concept of the buffer depth of a pipeline the\n- * application needs to maintain to also cover controls. Just as with buffer\n- * depth if the application keeps the number of requests queued above the\n- * control depth the controls are guaranteed to take effect for the correct\n- * request. The control depth is determined by the control with the greatest\n- * delay.\n+ * The idea is to maintain a queue of controls that have been submitted.\n+ * Whenever a new frame starts, we can \"peak back\" into this queue to send\n+ * controls at the correct number of frames in advance to account for each\n+ * control's delay.\n+ *\n+ * The overall delay for controls becomes the maximum delay of any of the\n+ * controls.\n */\n \n /**\n@@ -119,7 +120,6 @@ DelayedControls::DelayedControls(V4L2Device *device,\n */\n void DelayedControls::reset(unsigned int cookie)\n {\n-\tqueueCount_ = 1;\n \twriteCount_ = 0;\n \tcookies_[0] = cookie;\n \n@@ -146,18 +146,25 @@ void DelayedControls::reset(unsigned int cookie)\n * \\brief Push a set of controls on the queue\n * \\param[in] controls List of controls to add to the device queue\n *\n- * Push a set of controls to the control queue. This increases the control queue\n- * depth by one.\n+ * Push a set of controls to the control queue. The next call to applyControls\n+ * will advance the slot in the queue where the next call to push will write\n+ * controls.\n *\n * \\returns true if \\a controls are accepted, or false otherwise\n */\n bool DelayedControls::push(const ControlList &controls, const unsigned int cookie)\n {\n \t/* Copy state from previous frame. */\n-\tfor (auto &ctrl : values_) {\n-\t\tInfo &info = ctrl.second[queueCount_];\n-\t\tinfo = values_[ctrl.first][queueCount_ - 1];\n-\t\tinfo.updated = false;\n+\tif (writeCount_ > 0) {\n+\t\tfor (auto &ctrl : values_) {\n+\t\t\tInfo &info = ctrl.second[writeCount_];\n+\t\t\tinfo = values_[ctrl.first][writeCount_ - 1];\n+\t\t\tinfo.updated = false;\n+\t\t}\n+\t} else {\n+\t\t/* Although it works, we don't expect this. */\n+\t\tLOG(RPiDelayedControls, Warning)\n+\t\t\t<< \"push called before applyControls\";\n \t}\n \n \t/* Update with new controls. */\n@@ -175,18 +182,17 @@ bool DelayedControls::push(const ControlList &controls, const unsigned int cooki\n \t\tif (controlParams_.find(id) == controlParams_.end())\n \t\t\treturn false;\n \n-\t\tInfo &info = values_[id][queueCount_];\n+\t\tInfo &info = values_[id][writeCount_];\n \n \t\tinfo = Info(control.second);\n \n \t\tLOG(RPiDelayedControls, Debug)\n \t\t\t<< \"Queuing \" << id->name()\n \t\t\t<< \" to \" << info.toString()\n-\t\t\t<< \" at index \" << queueCount_;\n+\t\t\t<< \" at index \" << writeCount_;\n \t}\n \n-\tcookies_[queueCount_] = cookie;\n-\tqueueCount_++;\n+\tcookies_[writeCount_] = cookie;\n \n \treturn true;\n }\n@@ -200,9 +206,9 @@ bool DelayedControls::push(const ControlList &controls, const unsigned int cooki\n * the callers responsibility to not read too old sequence numbers that have been\n * pushed out of the history.\n *\n- * Historic values are evicted by pushing new values onto the queue using\n- * push(). The max history from the current sequence number that yields valid\n- * values are thus 16 minus number of controls pushed.\n+ * Historic values are evicted by new frames arriving and applyControls\n+ * advancing the head of the queue in the ring buffer. The valid history in\n+ * the queue consists of 16 entries from this head of the queue.\n *\n * \\return The controls at \\a sequence number\n */\n@@ -234,6 +240,10 @@ std::pair<ControlList, unsigned int> DelayedControls::get(uint32_t sequence)\n * number. Any user of these helpers is responsible to inform the helper about\n * the start of any frame. This can be connected with ease to the start of a\n * exposure (SOE) V4L2 event.\n+ *\n+ * Controls will be sent to the device, each staggered by the appropriate\n+ * number of frames for that control, so that they are applied at the same\n+ * time.\n */\n void DelayedControls::applyControls(uint32_t sequence)\n {\n@@ -277,12 +287,12 @@ void DelayedControls::applyControls(uint32_t sequence)\n \t\t}\n \t}\n \n-\twriteCount_ = sequence + 1;\n-\n-\twhile (writeCount_ > queueCount_) {\n+\twhile (writeCount_ < sequence + 1) {\n+\t\twriteCount_++;\n \t\tLOG(RPiDelayedControls, Debug)\n-\t\t\t<< \"Queue is empty, auto queue no-op.\";\n-\t\tpush({}, cookies_[queueCount_ - 1]);\n+\t\t\t<< \"Pushing noop with for index \" << writeCount_\n+\t\t\t<< \" with cookie \" << cookies_[writeCount_ - 1];\n+\t\tpush({}, cookies_[writeCount_ - 1]);\n \t}\n \n \tdevice_->setControls(&out);\ndiff --git a/src/libcamera/pipeline/rpi/common/delayed_controls.h b/src/libcamera/pipeline/rpi/common/delayed_controls.h\nindex 487b0057..48ad5a0f 100644\n--- a/src/libcamera/pipeline/rpi/common/delayed_controls.h\n+++ b/src/libcamera/pipeline/rpi/common/delayed_controls.h\n@@ -76,7 +76,6 @@ private:\n \tstd::unordered_map<const ControlId *, ControlParams> controlParams_;\n \tunsigned int maxDelay_;\n \n-\tuint32_t queueCount_;\n \tuint32_t writeCount_;\n \tstd::unordered_map<const ControlId *, RingBuffer<Info>> values_;\n \tRingBuffer<unsigned int> cookies_;\n", "prefixes": [ "v5", "1/3" ] }