{"id":25085,"url":"https://patchwork.libcamera.org/api/patches/25085/?format=json","web_url":"https://patchwork.libcamera.org/patch/25085/","project":{"id":1,"url":"https://patchwork.libcamera.org/api/projects/1/?format=json","name":"libcamera","link_name":"libcamera","list_id":"libcamera_core","list_email":"libcamera-devel@lists.libcamera.org","web_url":"","scm_url":"","webscm_url":""},"msgid":"<20251120094919.12138-1-robert.mader@collabora.com>","date":"2025-11-20T09:49:19","name":"qcam: Sync buffers before import","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"3e9e433bd19fbadc7d573c64c251413372de5ca4","submitter":{"id":140,"url":"https://patchwork.libcamera.org/api/people/140/?format=json","name":"Robert Mader","email":"robert.mader@collabora.com"},"delegate":null,"mbox":"https://patchwork.libcamera.org/patch/25085/mbox/","series":[{"id":5596,"url":"https://patchwork.libcamera.org/api/series/5596/?format=json","web_url":"https://patchwork.libcamera.org/project/libcamera/list/?series=5596","date":"2025-11-20T09:49:19","name":"qcam: Sync buffers before import","version":1,"mbox":"https://patchwork.libcamera.org/series/5596/mbox/"}],"comments":"https://patchwork.libcamera.org/api/patches/25085/comments/","check":"pending","checks":"https://patchwork.libcamera.org/api/patches/25085/checks/","tags":{},"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 71C18C0F1B\n\tfor ;\n\tThu, 20 Nov 2025 09:50:00 +0000 (UTC)","from lancelot.ideasonboard.com (localhost [IPv6:::1])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTP id A46C7606E6;\n\tThu, 20 Nov 2025 10:49:59 +0100 (CET)","from sender3-pp-f112.zoho.com (sender3-pp-f112.zoho.com\n\t[136.143.184.112])\n\tby lancelot.ideasonboard.com (Postfix) with ESMTPS id BA170606E6\n\tfor ;\n\tThu, 20 Nov 2025 10:49:57 +0100 (CET)","by mx.zohomail.com with SMTPS id 1763632190746400.6753210444941;\n\tThu, 20 Nov 2025 01:49:50 -0800 (PST)"],"Authentication-Results":"lancelot.ideasonboard.com; dkim=pass (1024-bit key;\n\tunprotected) header.d=collabora.com\n\theader.i=robert.mader@collabora.com header.b=\"PN+lxRFN\"; \n\tdkim-atps=neutral","ARC-Seal":"i=1; a=rsa-sha256; t=1763632192; cv=none; \n\td=zohomail.com; s=zohoarc; \n\tb=ejXNiCBIXkRi/VD1GqSFWGCnrKT1BtukHm81d0SR+5kCIvxgTyyt3578e+OsI6K/f+ozgcPYIspAue8U8I52Ps6OOCE4vOLoEzNoWt1uS4N82l/vjXNpKLud2ddP00Qq9QE2lHMdf5TPqlEb//Xbuo5yp3svUn0fE1W0OsQFY9I=","ARC-Message-Signature":"i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; \n\ts=zohoarc; t=1763632192;\n\th=Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:MIME-Version:Message-ID:Subject:Subject:To:To:Message-Id:Reply-To;\n\tbh=+iIAm30aDRC67zfxTSzYYlgjiEwVx4EFyui3p76t5wE=; \n\tb=ZxOLMYp8SlVUsju+8IPBg3IfYKopwhvxi35c0LMRUd0HACCOf/XedTmSMkow4C1+/Rx7IdnUaQoxQGXIg5pAbDJ5GUzUSkbOPsrWV1D92Gi+2b8rwOPI5T90/ojL/Yu0+QsncU2EzMZZbdY7MgBcUH0fXkIc1RfOKen8+g81TGM=","ARC-Authentication-Results":"i=1; mx.zohomail.com;\n\tdkim=pass header.i=collabora.com;\n\tspf=pass smtp.mailfrom=robert.mader@collabora.com;\n\tdmarc=pass header.from=","DKIM-Signature":"v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1763632192;\n\ts=zohomail; d=collabora.com; i=robert.mader@collabora.com;\n\th=From:From:To:To:Cc:Cc:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Transfer-Encoding:Message-Id:Reply-To;\n\tbh=+iIAm30aDRC67zfxTSzYYlgjiEwVx4EFyui3p76t5wE=;\n\tb=PN+lxRFN7zipSFR+3Ltbb/mi/HkWJr5pX8OtMtYg//f9rKM0zrkgDMcQxQBw5HzV\n\tdDi6bD/AcymzS4kVp+PzeJ+UkJmqqf1vwth3sv9MQqszWMqpzAFuME+pA8wcELfabzo\n\tzptdbLofAv2KSfoVcz2YgFdJiqNGOxkqJNVROx2M=","From":"Robert Mader ","To":"libcamera-devel@lists.libcamera.org","Cc":"Robert Mader ","Subject":"[PATCH] qcam: Sync buffers before import","Date":"Thu, 20 Nov 2025 10:49:19 +0100","Message-ID":"<20251120094919.12138-1-robert.mader@collabora.com>","X-Mailer":"git-send-email 2.51.1","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":"","List-Unsubscribe":",\n\t","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n\t","Errors-To":"libcamera-devel-bounces@lists.libcamera.org","Sender":"\"libcamera-devel\" "},"content":"Use the DmaSyncer handler to ensure the data from the buffer is\ncoherent. This is required by the spec - from\nhttps://docs.kernel.org/driver-api/dma-buf.html#c.dma_buf_sync:\n\n> When a DMA buffer is accessed from the CPU via mmap, it is not always\n> possible to guarantee coherency between the CPU-visible map and\n> underlying memory. To manage coherency, DMA_BUF_IOCTL_SYNC must be used\n> to bracket any CPU access to give the kernel the chance to shuffle memory\n> around if needed.\n\nThis was reported to fix glitches with the upcoming GPU-ISP, in which\ncase the accessed data in written by the GPU.\n\nNote that in the GPU-ISP case we are effectively seeing a round-trip of\nthe buffer contents - from GPU synced to CPU, copied to GPU again. We\ncould avoid that in the future by implementing direct dmabuf import in\nqcam.\n\nSigned-off-by: Robert Mader \n---\n src/apps/qcam/viewfinder_gl.cpp | 10 ++++++++--\n src/apps/qcam/viewfinder_qt.cpp | 11 +++++++++++\n 2 files changed, 19 insertions(+), 2 deletions(-)","diff":"diff --git a/src/apps/qcam/viewfinder_gl.cpp b/src/apps/qcam/viewfinder_gl.cpp\nindex f31956ff0..0121c97ad 100644\n--- a/src/apps/qcam/viewfinder_gl.cpp\n+++ b/src/apps/qcam/viewfinder_gl.cpp\n@@ -9,14 +9,16 @@\n \n #include \n \n+#include \n+\n+#include \"libcamera/internal/dma_buf_allocator.h\"\n+\n #include \n #include \n #include \n #include \n #include \n \n-#include \n-\n #include \"../common/image.h\"\n \n static const QList supportedFormats{\n@@ -542,6 +544,10 @@ void ViewFinderGL::doRender()\n \t/* Stride of the first plane, in pixels. */\n \tunsigned int stridePixels;\n \n+\tstd::vector dmaSyncers;\n+\tfor (const libcamera::FrameBuffer::Plane &plane : buffer_->planes())\n+\t\tdmaSyncers.emplace_back(plane.fd, libcamera::DmaSyncer::SyncType::Read);\n+\n \tswitch (format_) {\n \tcase libcamera::formats::NV12:\n \tcase libcamera::formats::NV21:\ndiff --git a/src/apps/qcam/viewfinder_qt.cpp b/src/apps/qcam/viewfinder_qt.cpp\nindex 1a238922b..4d00f154d 100644\n--- a/src/apps/qcam/viewfinder_qt.cpp\n+++ b/src/apps/qcam/viewfinder_qt.cpp\n@@ -11,6 +11,7 @@\n #include \n #include \n \n+#include \"libcamera/internal/dma_buf_allocator.h\"\n #include \n \n #include \n@@ -114,6 +115,10 @@ void ViewFinderQt::render(libcamera::FrameBuffer *buffer, Image *image)\n \t\t\t * Otherwise, convert the format and release the frame\n \t\t\t * buffer immediately.\n \t\t\t */\n+\t\t\tstd::vector dmaSyncers;\n+\t\t\tfor (const libcamera::FrameBuffer::Plane &plane : buffer->planes())\n+\t\t\t\tdmaSyncers.emplace_back(plane.fd, libcamera::DmaSyncer::SyncType::Read);\n+\n \t\t\tconverter_.convert(image, size, &image_);\n \t\t}\n \t}\n@@ -161,6 +166,12 @@ void ViewFinderQt::paintEvent(QPaintEvent *)\n \n \t/* If we have an image, draw it, with black letterbox rectangles. */\n \tif (!image_.isNull()) {\n+\t\tif (buffer_) {\n+\t\t\tstd::vector dmaSyncers;\n+\t\t\tfor (const libcamera::FrameBuffer::Plane &plane : buffer_->planes())\n+\t\t\t\tdmaSyncers.emplace_back(plane.fd, libcamera::DmaSyncer::SyncType::Read);\n+\t\t}\n+\n \t\tif (place_.width() < width()) {\n \t\t\tQRect rect{ 0, 0, (width() - place_.width()) / 2, height() };\n \t\t\tpainter.drawRect(rect);\n","prefixes":[]}