From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DD0E71DF987; Sun, 1 Feb 2026 20:06:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769976415; cv=none; b=OIDsKnI6iFrQa0PxBNUu7cFpF7zfIyF/t73A15uS5edWyp8QjlEMKdokX84kNtRz2DbBUuu0fdDb6KZ2R35HpJVX9i4eBUr5x7nDeDzc4gT8CVjgQcugAJuVkphAvNoj7LsqHXLv7H0mprCkVCGEslBcJnB1IZ/VMP6MUSTuPgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769976415; c=relaxed/simple; bh=vaCDMVxeae+zPHzcYJkZ6gPRr/Oj8xlx/FLS4UMBdhs=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=aC9xcRiBmUROb0GeNVfjjz8b3cSBQZoAkwGVAyp6+FiPYevtQ4qbqQd6eRngxU7Om7OEH21Tnd+f4BKIVaIagfk3dV0Zdnn8ITmzPxs39VY71sWvZV+wi7cM76TY1S5S97R5f6MjFpJl5BxyHFkEjq2j98iH3EPLFXOb4e5M3m0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=H2p6vmhJ; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="H2p6vmhJ" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id 2F2EB1BA; Sun, 1 Feb 2026 21:06:11 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1769976371; bh=vaCDMVxeae+zPHzcYJkZ6gPRr/Oj8xlx/FLS4UMBdhs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=H2p6vmhJ521cQBDEJaanSabS/ZjcnQ9UWggdEZepFtWi4PtD1MIMFNbido4li7DMS vLZfWdVe4gq4Y40r7QRKkDMoOuVeplgmM0xYPk1xo9eJzESUqeb/xfHEfG9HtoToLt k+GcGiM0nHNatX7ZRGYgfYsbe9I92phiU3TtlPPg= Date: Sun, 1 Feb 2026 22:06:49 +0200 From: Laurent Pinchart To: Jarkko Sakkinen Cc: linux-media@vger.kernel.org, jani.nikula@linux.intel.com, anisse@astier.eu, oleksandr@natalenko.name, Mauro Carvalho Chehab , Hans Verkuil , Sakari Ailus , Jacopo Mondi , Ricardo Ribalda , open list Subject: Re: [RFC PATCH] media: Virtual camera driver Message-ID: <20260201200649.GW3374091@killaraus> References: <20260201133342.335680-1-jarkko@kernel.org> <20260201182011.GV3374091@killaraus> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: On Sun, Feb 01, 2026 at 09:04:00PM +0200, Jarkko Sakkinen wrote: > On Sun, Feb 01, 2026 at 08:20:11PM +0200, Laurent Pinchart wrote: > > On Sun, Feb 01, 2026 at 03:33:38PM +0200, Jarkko Sakkinen wrote: > > > vcam is a DMA-BUF backed virtual camera driver capable of creating video > > > capture devices to which data can be streamed through /dev/vcam after > > > calling VCAM_IOC_CREATE. Frames are pushed with VCAM_IOC_QUEUE and recycled > > > with VCAM_IOC_DEQUEUE. > > > > > > Zero-copy semantics are supported for shared DMA-BUF between capture and > > > output. > > > > > > Signed-off-by: Jarkko Sakkinen > > > --- > > > Early feedback e.g., is this completely in wrong direction? V4L2 world > > > is relatively alien world, and thus I need a sanity check ;-) > > > > We already have multiple virtual drivers, including vivid and vimc. > > Could you please explain the rationale for yet another one, and why the > > new features it provides (if any) can't be added to existing drivers ? > > There is a notable user base for v4l2-loopback. It is the defacto choice > for streaming phone cams. This will then likely face the same hurdles as v4l2-loopback, the main one being that camera support should be upstreamed with proper drivers instead of a closed-source userspace daemon. For phone cameras, the way forward upstream is libcamera. Until kernel drivers for ISPs are available, the soft ISP is a stop-gap solution. It recently gained GPU acceleration support (with work to improve image quality with additional algorithms ongoing). > The motivation here is to provide a service optimized for that use and > purpose. It's virtual but non-generic i.e. not aimed for testing/emulation. > > > > .../driver-api/media/drivers/index.rst | 1 + > > > .../driver-api/media/drivers/vcam.rst | 16 + > > > MAINTAINERS | 8 + > > > drivers/media/Kconfig | 13 + > > > drivers/media/Makefile | 1 + > > > drivers/media/vcam.c | 1700 +++++++++++++++++ > > > include/uapi/linux/vcam.h | 124 ++ > > > 7 files changed, 1863 insertions(+) > > > create mode 100644 Documentation/driver-api/media/drivers/vcam.rst > > > create mode 100644 drivers/media/vcam.c > > > create mode 100644 include/uapi/linux/vcam.h [snip] -- Regards, Laurent Pinchart