[{"id":37208,"web_url":"https://patchwork.libcamera.org/comment/37208/","msgid":"<85ldjjz2nh.fsf@mzamazal-thinkpadp1gen7.tpbc.csb>","date":"2025-12-03T21:17:06","subject":"Re: [PATCH v6 23/24] libcamera: software_isp: lut: Skip calculation\n\tlookup tables if gpuIspEnabled is true.","submitter":{"id":177,"url":"https://patchwork.libcamera.org/api/people/177/","name":"Milan Zamazal","email":"mzamazal@redhat.com"},"content":"Bryan O'Donoghue writes:\n\n> On my reference platform Qualcomm RB5 sm8520 the qcam application CPU\n> occupancy drops from ~100% to about 95% of a single core so this one change\n> sheds aprox 5% CPU usage.\n>\n> Signed-off-by: Bryan O'Donoghue \n\nNo dot at the end of the commit title.\n\nReviewed-by: Milan Zamazal \n\n> ---\n> src/ipa/simple/algorithms/lut.cpp | 70 ++++++++++++++++---------------\n> 1 file changed, 37 insertions(+), 33 deletions(-)\n>\n> diff --git a/src/ipa/simple/algorithms/lut.cpp b/src/ipa/simple/algorithms/lut.cpp\n> index 7f223e812..618219b17 100644\n> --- a/src/ipa/simple/algorithms/lut.cpp\n> +++ b/src/ipa/simple/algorithms/lut.cpp\n> @@ -56,32 +56,34 @@ void Lut::queueRequest(typename Module::Context &context,\n> \n> void Lut::updateGammaTable(IPAContext &context)\n> {\n> -\tauto &gammaTable = context.activeState.gamma.gammaTable;\n> \tconst auto blackLevel = context.activeState.blc.level;\n> -\tconst unsigned int blackIndex = blackLevel * gammaTable.size() / 256;\n> \tconst auto contrast = context.activeState.knobs.contrast.value_or(1.0);\n> \n> -\tconst float divisor = gammaTable.size() - blackIndex - 1.0;\n> -\tfor (unsigned int i = blackIndex; i < gammaTable.size(); i++) {\n> -\t\tdouble normalized = (i - blackIndex) / divisor;\n> -\t\t/* Convert 0..2 to 0..infinity; avoid actual inifinity at tan(pi/2) */\n> -\t\tdouble contrastExp = tan(std::clamp(contrast * M_PI_4, 0.0, M_PI_2 - 0.00001));\n> -\t\t/* Apply simple S-curve */\n> -\t\tif (normalized < 0.5)\n> -\t\t\tnormalized = 0.5 * std::pow(normalized / 0.5, contrastExp);\n> -\t\telse\n> -\t\t\tnormalized = 1.0 - 0.5 * std::pow((1.0 - normalized) / 0.5, contrastExp);\n> -\t\tgammaTable[i] = UINT8_MAX *\n> -\t\t\t\tstd::pow(normalized, context.configuration.gamma);\n> +\tif (!context.gpuIspEnabled) {\n> +\t\tauto &gammaTable = context.activeState.gamma.gammaTable;\n> +\t\tconst unsigned int blackIndex = blackLevel * gammaTable.size() / 256;\n> +\t\tconst float divisor = gammaTable.size() - blackIndex - 1.0;\n> +\t\tfor (unsigned int i = blackIndex; i < gammaTable.size(); i++) {\n> +\t\t\tdouble normalized = (i - blackIndex) / divisor;\n> +\t\t\t/* Convert 0..2 to 0..infinity; avoid actual inifinity at tan(pi/2) */\n> +\t\t\tdouble contrastExp = tan(std::clamp(contrast * M_PI_4, 0.0, M_PI_2 - 0.00001));\n> +\t\t\t/* Apply simple S-curve */\n> +\t\t\tif (normalized < 0.5)\n> +\t\t\t\tnormalized = 0.5 * std::pow(normalized / 0.5, contrastExp);\n> +\t\t\telse\n> +\t\t\t\tnormalized = 1.0 - 0.5 * std::pow((1.0 - normalized) / 0.5, contrastExp);\n> +\t\t\tgammaTable[i] = UINT8_MAX *\n> +\t\t\t\t\tstd::pow(normalized, context.configuration.gamma);\n> +\t\t}\n> +\t\t/*\n> +\t\t * Due to CCM operations, the table lookup may reach indices below the black\n> +\t\t * level. Let's set the table values below black level to the minimum\n> +\t\t * non-black value to prevent problems when the minimum value is\n> +\t\t * significantly non-zero (for example, when the image should be all grey).\n> +\t\t */\n> +\t\tstd::fill(gammaTable.begin(), gammaTable.begin() + blackIndex,\n> +\t\t\t gammaTable[blackIndex]);\n> \t}\n> -\t/*\n> -\t * Due to CCM operations, the table lookup may reach indices below the black\n> -\t * level. Let's set the table values below black level to the minimum\n> -\t * non-black value to prevent problems when the minimum value is\n> -\t * significantly non-zero (for example, when the image should be all grey).\n> -\t */\n> -\tstd::fill(gammaTable.begin(), gammaTable.begin() + blackIndex,\n> -\t\t gammaTable[blackIndex]);\n> \n> \tcontext.activeState.gamma.blackLevel = blackLevel;\n> \tcontext.activeState.gamma.contrast = contrast;\n> @@ -134,17 +136,19 @@ void Lut::prepare(IPAContext &context,\n> \t\tauto &green = params->greenCcm;\n> \t\tauto &blue = params->blueCcm;\n> \t\tparams->ccm = ccm;\n> -\t\tfor (unsigned int i = 0; i < DebayerParams::kRGBLookupSize; i++) {\n> -\t\t\tred[i].r = ccmValue(i, ccm[0][0]);\n> -\t\t\tred[i].g = ccmValue(i, ccm[1][0]);\n> -\t\t\tred[i].b = ccmValue(i, ccm[2][0]);\n> -\t\t\tgreen[i].r = ccmValue(i, ccm[0][1]);\n> -\t\t\tgreen[i].g = ccmValue(i, ccm[1][1]);\n> -\t\t\tgreen[i].b = ccmValue(i, ccm[2][1]);\n> -\t\t\tblue[i].r = ccmValue(i, ccm[0][2]);\n> -\t\t\tblue[i].g = ccmValue(i, ccm[1][2]);\n> -\t\t\tblue[i].b = ccmValue(i, ccm[2][2]);\n> -\t\t\tparams->gammaLut[i] = gammaTable[i / div];\n> +\t\tif (!context.gpuIspEnabled) {\n> +\t\t\tfor (unsigned int i = 0; i < DebayerParams::kRGBLookupSize; i++) {\n> +\t\t\t\tred[i].r = ccmValue(i, ccm[0][0]);\n> +\t\t\t\tred[i].g = ccmValue(i, ccm[1][0]);\n> +\t\t\t\tred[i].b = ccmValue(i, ccm[2][0]);\n> +\t\t\t\tgreen[i].r = ccmValue(i, ccm[0][1]);\n> +\t\t\t\tgreen[i].g = ccmValue(i, ccm[1][1]);\n> +\t\t\t\tgreen[i].b = ccmValue(i, ccm[2][1]);\n> +\t\t\t\tblue[i].r = ccmValue(i, ccm[0][2]);\n> +\t\t\t\tblue[i].g = ccmValue(i, ccm[1][2]);\n> +\t\t\t\tblue[i].b = ccmValue(i, ccm[2][2]);\n> +\t\t\t\tparams->gammaLut[i] = gammaTable[i / div];\n> +\t\t\t}\n> \t\t}\n> \t}","headers":{"Return-Path":"","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 A0960BD80A\n\tfor ;\n\tWed, 3 Dec 2025 21:17:15 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id A7A56610B2;\n\tWed, 3 Dec 2025 22:17:14 +0100 (CET)","from us-smtp-delivery-124.mimecast.com\n\t(us-smtp-delivery-124.mimecast.com [170.10.133.124])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id 5FD46609D8\n\tfor ;\n\tWed, 3 Dec 2025 22:17:12 +0100 (CET)","from mail-wr1-f71.google.com (mail-wr1-f71.google.com\n\t[209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS\n\t(version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id\n\tus-mta-636-14UoxpVvO2aRJMOTmKP75w-1; Wed, 03 Dec 2025 16:17:10 -0500","by mail-wr1-f71.google.com with SMTP id\n\tffacd0b85a97d-42b366a76ffso133653f8f.1\n\tfor ;\n\tWed, 03 Dec 2025 13:17:10 -0800 (PST)","from mzamazal-thinkpadp1gen7.tpbc.csb\n\t(ip-77-48-47-2.net.vodafone.cz. 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