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GET /api/1.1/patches/25625/?format=api
{ "id": 25625, "url": "https://patchwork.libcamera.org/api/1.1/patches/25625/?format=api", "web_url": "https://patchwork.libcamera.org/patch/25625/", "project": { "id": 1, "url": "https://patchwork.libcamera.org/api/1.1/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": "<20260105-softisp-agc-v3-1-434f2053c549@mainlining.org>", "date": "2026-01-05T13:57:44", "name": "[v3] ipa: simple: fix minimal analog gain init", "commit_ref": "98e5e561502bdff0da6e58fe265846906bf72816", "pull_url": null, "state": "accepted", "archived": false, "hash": "d7a89ad8e7b3236cd683660548f7a84a0f3e299f", "submitter": { "id": 255, "url": "https://patchwork.libcamera.org/api/1.1/people/255/?format=api", "name": "Vasiliy Doylov", "email": "nekocwd@mainlining.org" }, "delegate": null, "mbox": "https://patchwork.libcamera.org/patch/25625/mbox/", "series": [ { "id": 5684, "url": "https://patchwork.libcamera.org/api/1.1/series/5684/?format=api", "web_url": "https://patchwork.libcamera.org/project/libcamera/list/?series=5684", "date": "2026-01-05T13:57:44", "name": "[v3] ipa: simple: fix minimal analog gain init", "version": 3, "mbox": "https://patchwork.libcamera.org/series/5684/mbox/" } ], "comments": "https://patchwork.libcamera.org/api/patches/25625/comments/", "check": "pending", "checks": "https://patchwork.libcamera.org/api/patches/25625/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 80EF1BDCBF\n\tfor <parsemail@patchwork.libcamera.org>;\n\tMon, 5 Jan 2026 13:57:50 +0000 (UTC)", "from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id 7AE5661F9F;\n\tMon, 5 Jan 2026 14:57:49 +0100 (CET)", "from mail.mainlining.org (mail.mainlining.org [5.75.144.95])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 9B55761F35\n\tfor <libcamera-devel@lists.libcamera.org>;\n\tMon, 5 Jan 2026 14:57:47 +0100 (CET)" ], "Authentication-Results": "lancelot.ideasonboard.com; dkim=pass (2048-bit key;\n\tunprotected) header.d=mainlining.org header.i=@mainlining.org\n\theader.b=\"Z4BfCbKt\"; \n\tdkim=permerror (0-bit key) header.d=mainlining.org\n\theader.i=@mainlining.org header.b=\"cROYHTk8\"; \n\tdkim-atps=neutral", "DKIM-Signature": [ "v=1; a=rsa-sha256; s=202507r; d=mainlining.org;\n\tc=relaxed/relaxed; \n\th=To:Message-Id:Subject:Date:From; t=1767621466;\n\tbh=P6aC8/wJfDc3eZbabp7oMGX hXk1z3n/2GtV14rcaiuo=;\n\tb=Z4BfCbKt/tPOdMmv1UiVDes8qhS4oFJI/bC+HgexWKedSOTaer\n\t0yhyvw45wh3IbLEZ3UZ8YWSNG00qvPGtyrjT+HpOeF+O45NNmZ0kfIFDBOJWlk00I8NWzg+mKVR\n\tkCJ4pwphT8qaqSfnun26A7FPZT9T1V0g/qXWnhgrv2yw3LGES6nRstFZyxKTYbJElh1pPtMtcfE\n\tdz77z00GZ+f5wrO6dL8Whx/BYfruVQ6cAalnZxIWTN9XBhtQfYJZQM9Ix9KKf7PFTyWbLScK9Zi\n\tACePFwZiJjsGLs0K5lrWrvDAOkrUuMDfjXenPtnpR/hjl+ocyyEuXDw7PlzZvbP3cug==;", "v=1; a=ed25519-sha256; s=202507e; d=mainlining.org;\n\tc=relaxed/relaxed; \n\th=To:Message-Id:Subject:Date:From; t=1767621466;\n\tbh=P6aC8/wJfDc3eZbabp7oMGX hXk1z3n/2GtV14rcaiuo=;\n\tb=cROYHTk83khw3tq98snCwVNxguihUEmDUXE05qZopDKVbDwU+H\n\tcOnO5Lz+icW5fNZKds3eBmy9KLlG9dCnuhBA==;" ], "From": "Vasiliy Doylov <nekocwd@mainlining.org>", "Date": "Mon, 05 Jan 2026 16:57:44 +0300", "Subject": "[PATCH v3] ipa: simple: fix minimal analog gain init", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=\"utf-8\"", "Content-Transfer-Encoding": "7bit", "Message-Id": "<20260105-softisp-agc-v3-1-434f2053c549@mainlining.org>", "X-B4-Tracking": "v=1; b=H4sIAFfDW2kC/33MSwrCMBSF4a2UOzaSh0ltR+5DHMTm0QualKQEp\n\tXTvpp0qDv8D51sg24Q2Q98skGzBjDHUEIcGhlEHbwma2sApV5RRSXJ0M+aJaD8Qpgxlw10Yfeq\n\tgPqZkHb527XqrPWKeY3rveGHb+tspjDDStoorSeVZCn15agwPDBj8MSYPG1b4H4BXoKNMWNUJ5\n\t4z8AtZ1/QDK3NxC7AAAAA==", "X-Change-ID": "20260105-softisp-agc-16d01cb3da49", "To": "libcamera-devel@lists.libcamera.org", "Cc": "Vasiliy Doylov <nekocwd@mainlining.org>", "X-Mailer": "b4 0.14.3", "X-Developer-Signature": "v=1; a=openpgp-sha256; l=2700;\n\ti=nekocwd@mainlining.org; h=from:subject:message-id;\n\tbh=s0qQ1gzIuIiwsI8h3KTDHwEJsYF25Y1Uk//f/fs9mRU=;\n\tb=owGbwMvMwCXGd//xporA/cmMp9WSGDKjD0fN0L1+5Xu6nqUXc77tn6mLNZW7N6nmxvpYVulF9\n\txtejS3sKGVhEONikBVTZPlvuEjuwA1lz7rc1Gcwc1iZQIYwcHEKwESyvzD8L8hP6do+p/7p2t18\n\tS48W8MUteXawnNfi/U/9NTmlXhrfMxn+R0/8MMmihz1Oit9JrUNx7dv/Nd9vJZ41iXVZ4rX8qud\n\tSdgA=", "X-Developer-Key": "i=nekocwd@mainlining.org; a=openpgp;\n\tfpr=FF31A21EC0D823497E6D65E60EDFE3B27851BF63", "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": "On most imx sensors the formula seems to be:\n\nagain_float = 512.0 / (512.0 - again_ctrl_value)\n\nSo the minimum again of 0 makes sense and actually translates to a gain of 1.0.\nAnd the max gain of 400 leads to 512.0 / 112.0 = 4.57 which is about typical for\na maximum again. Since a minimum again value of 0 is actually normal, the special\nhandling of againMin == 0 is undesirable and this is actually causing problems\non these IMX sensors. again10 correctly gets set to 0 which is less then the\nadjusted againMin which causes the AGC code to not work properly.\n\nFix this by dropping the special handling of againMin == 0.\n\nSigned-off-by: Vasiliy Doylov <nekocwd@mainlining.org>\n---\nChanges in v3:\n- Expanded commit message\n- Link to v2: https://lists.libcamera.org/pipermail/libcamera-devel/2026-January/056068.html\n\nChanges in v2:\n- Drop old solution\n- Fix minimal analog gain initialisation\n- Link to v1: https://lists.libcamera.org/pipermail/libcamera-devel/2026-January/056045.html\n---\n src/ipa/simple/soft_simple.cpp | 19 +------------------\n 1 file changed, 1 insertion(+), 18 deletions(-)\n\n\n---\nbase-commit: 2861817f09c96a0660b88783eff159631e42030f\nchange-id: 20260105-softisp-agc-16d01cb3da49\n\nBest regards,", "diff": "diff --git a/src/ipa/simple/soft_simple.cpp b/src/ipa/simple/soft_simple.cpp\nindex b147aca2..dde11666 100644\n--- a/src/ipa/simple/soft_simple.cpp\n+++ b/src/ipa/simple/soft_simple.cpp\n@@ -237,26 +237,9 @@ int IPASoftSimple::configure(const IPAConfigInfo &configInfo)\n \t\t\t\tcamHelper_->blackLevel().value() / 256;\n \t\t}\n \t} else {\n-\t\t/*\n-\t\t * The camera sensor gain (g) is usually not equal to the value written\n-\t\t * into the gain register (x). But the way how the AGC algorithm changes\n-\t\t * the gain value to make the total exposure closer to the optimum\n-\t\t * assumes that g(x) is not too far from linear function. If the minimal\n-\t\t * gain is 0, the g(x) is likely to be far from the linear, like\n-\t\t * g(x) = a / (b * x + c). To avoid unexpected changes to the gain by\n-\t\t * the AGC algorithm (abrupt near one edge, and very small near the\n-\t\t * other) we limit the range of the gain values used.\n-\t\t */\n \t\tcontext_.configuration.agc.againMax = againMax;\n \t\tcontext_.configuration.agc.again10 = againDef;\n-\t\tif (againMin) {\n-\t\t\tcontext_.configuration.agc.againMin = againMin;\n-\t\t} else {\n-\t\t\tLOG(IPASoft, Warning)\n-\t\t\t\t<< \"Minimum gain is zero, that can't be linear\";\n-\t\t\tcontext_.configuration.agc.againMin =\n-\t\t\t\tstd::min(100, againMin / 2 + againMax / 2);\n-\t\t}\n+\t\tcontext_.configuration.agc.againMin = againMin;\n \t\tcontext_.configuration.agc.againMinStep = 1.0;\n \t}\n \n", "prefixes": [ "v3" ] }