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{ "id": 26672, "url": "https://patchwork.libcamera.org/api/patches/26672/?format=api", "web_url": "https://patchwork.libcamera.org/patch/26672/", "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": "<20260507125458.12140-2-david.plowman@raspberrypi.com>", "date": "2026-05-07T12:20:34", "name": "[v4,1/3] pipeline: rpi: Simplify delayed controls", "commit_ref": null, "pull_url": null, "state": "superseded", "archived": false, "hash": "118d6df606795b38292c25a09b55b1d06020b47c", "submitter": { "id": 42, "url":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/26672/mbox/", "series": [ { "id": 5917, "url": "https://patchwork.libcamera.org/api/series/5917/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=5917", "date": "2026-05-07T12:20:33", "name": "Atomic control lists on Raspberry Pi", "version": 4, "mbox": "https://patchwork.libcamera.org/series/5917/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/26672/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/26672/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 B9592C32F6\n\tfor <parsemail@patchwork.libcamera.org>;\n\tThu, 7 May 2026 12:55:07 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 8CFEE63020;\n\tThu, 7 May 2026 14:55:05 +0200 (CEST)", "from mail-wr1-x430.google.com (mail-wr1-x430.google.com\n\t[IPv6:2a00:1450:4864:20::430])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id E2B3D62010\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tThu, 7 May 2026 14:55:02 +0200 (CEST)", "by mail-wr1-x430.google.com with SMTP id\n\tffacd0b85a97d-44e1860558fso600771f8f.0\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tThu, 07 May 2026 05:55:02 -0700 (PDT)", "from davidp-pi5.pitowers.org\n\t([2a00:1098:3142:1f:88ea:c658:5b20:5e46])\n\tby smtp.gmail.com with ESMTPSA id\n\tffacd0b85a97d-450524833e1sm20396324f8f.2.2026.05.07.05.55.01\n\t(version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256);\n\tThu, 07 May 2026 05:55:01 -0700 (PDT)" ], "Authentication-Results": "lancelot.ideasonboard.com; dkim=pass (2048-bit key;\n\tunprotected) header.d=raspberrypi.com header.i=@raspberrypi.com\n\theader.b=\"bWzQLUsp\"; dkim-atps=neutral", "DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=raspberrypi.com; s=google; t=1778158502; x=1778763302;\n\tdarn=lists.libcamera.org; \n\th=content-transfer-encoding:mime-version:references:in-reply-to\n\t:message-id:date:subject:cc:to:from:from:to:cc:subject:date\n\t:message-id:reply-to;\n\tbh=B/6c4x6aPmSj4hSBbdqWEJNfL9gt9CXnVpTwIUpnx7A=;\n\tb=bWzQLUsp53Wgdgey1p+mfNd46z3nO4Md6r3bNmAkU0QC219xdsoWEKCO6d6m/KuuXv\n\t20TpWL4BMyBNnOa2eBPX1K50pZ6a+yR4egBdaNFHaGRlCXrU41ePcRjtZEI2GpZikcrv\n\tipWO+vJCRB2v7rF/z8IMIcME2QmSlPeRqJxfQGeb6jJGwJsy1HrUmiwGKbTgp1vi4HIV\n\tx8EOd6LV/iXxJYy414VC4Nea+9ReY6e0zhZ5gNTnJ8zwH9Z7KWYUOk3qMIBc8OLSWRL9\n\tWSF+paLQQsimt20jMmvbjR1VyQ8mG5WLq42151uSDLhQJp4i1KRQnB4r6mn0q0ngvhX+\n\tHSVw==", "X-Google-DKIM-Signature": "v=1; a=rsa-sha256; c=relaxed/relaxed;\n\td=1e100.net; s=20251104; t=1778158502; x=1778763302;\n\th=content-transfer-encoding:mime-version:references:in-reply-to\n\t:message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from\n\t:to:cc:subject:date:message-id:reply-to;\n\tbh=B/6c4x6aPmSj4hSBbdqWEJNfL9gt9CXnVpTwIUpnx7A=;\n\tb=k2qoByikWj6UVi2Y2VyIRF93jiBPIpz31/cB4D8wl73rlRcKx9XSXTfABa4aNH0yPy\n\tMPZPvxsfj3GlYKZ+N88BuIVchk4GahLoJhvH9IJPNgsUcYgyJZEaznjsqLC22aLk5TGW\n\tPolXiSf5q2rZr2khLxIDS50tH+/+zlERIo1G3YrGaVXicSvDnBE5Nh4y6X27wM42cvz9\n\tFImljWqHuljZ1Ym5yWAoDWDt8n+zewL4bFSQZAFJMcfHsNKKaW9SK6sqO6No9ra1nZIR\n\tJtOVFQJpMtJvl8+A0AgK9Q8Lz/ac69sT1niPVTKaAV099OAqKqa0YVgmcpfSNtZT7r0Z\n\t++aw==", "X-Gm-Message-State": "AOJu0Yy4PQTL3kPCnZWW7G18EnagUuyVfB3AN5CTG1ObaOl2SxmI9UWM\n\tg6CNkeskYLJcDKQuWUJIPujdM0K/ccVsmhs2VSrt3a59SZRhsJUrZWI2clTzCYczsXiExLb6097\n\tZyc0v", "X-Gm-Gg": "AeBDievDiG9L2gUJbLQWH9cASCFbzVx/xcZf2UFSSJyO0XV5BeVEB8Bfn5lT47unO/6\n\tqYPJ2TzgC5bsoNXGlAoIQN36GB3oKjI21rImag4e+yCy4DJpQ/aUYcLvumYM7vFd862VGe3Ce56\n\t0qTic2HoAU+VewlC8SR9NVa7oKTXSFo1qol8rtiptbVSXXupgY8f9ZryqoaKOA4k5O2YZxRvuk1\n\tUQXsbctollDyJOeQ0DXcRBI7E9KTofXHqDT+eOLqZZbsmKEEmxErF+j+CmZorQ4XDwAvwbeBzvP\n\tm1cjmZWqLBQ78XiJNVpfbHPZjdF9mI7yRJrPG9/VWv1ZKvhe0agwICgt/bg+kToqA3Zppqo/pAJ\n\tygSpQ00zfMOjEoTLnLltnxcI1re6UFrtOV07iAT5/KfPGpFHj+XLqG4yE9qIVebAsllNjReeEn0\n\tAs4WL3cYveVkjxqts+LaPOyI1loRk2lq7R70zDSD3T0E8KXNdyylPmzCrUaQZXdAsoj0D9eVQDQ\n\tfh/kGrvO0ziMwsxJeGCD5AMcsnQQymvoxW6P59q1iJHFemB3qqd", "X-Received": "by 2002:a05:6000:2901:b0:43d:613:4036 with SMTP id\n\tffacd0b85a97d-4515da9535bmr12535111f8f.37.1778158501943; \n\tThu, 07 May 2026 05:55:01 -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 v4 1/3] pipeline: rpi: Simplify delayed controls", "Date": "Thu, 7 May 2026 13:20:34 +0100", "Message-ID": "<20260507125458.12140-2-david.plowman@raspberrypi.com>", "X-Mailer": "git-send-email 2.47.3", "In-Reply-To": "<20260507125458.12140-1-david.plowman@raspberrypi.com>", "References": "<20260507125458.12140-1-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": [ "v4", "1/3" ] }