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 0D2C71487CB for ; Fri, 12 Apr 2024 19:07:56 +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=1712948878; cv=none; b=MLayKCeParx9opewJkBfWivBRNyjAZETaOCtLlyl7VdsyPYiiTynNykewp2ip3TDVShT2Z92SGIGr/4yeHGGORUBQdCUXFBNVf4IwR/CfMg06AZUWVoIp4cW3fOY3xSwbH70GTlTi+FFS2SCGC5TMYRD2sW28MuD/7XEauG0wTA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712948878; c=relaxed/simple; bh=iBuwmavZMJ5jpcg8mNizkJ/zoPhJeyREETJcIjhK4kI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nJGtZYl0LX0L8gA1Yex5ibSJnB3aVZ/oW5aNBAydiNOWnGn1EnVk+nWgWj7nr07N1PbttyKecZ7RpsoeAW4O2KG8YeD8l8XQ1ZuoDLNcH9KP2NdsLo3xyrjmHCvD/GNrqNFob9Dobq1lw4BOlrOznJB2znI2DToFX5vCfDfPX9k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=XgTk8cbI; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="XgTk8cbI" Received: from pendragon.ideasonboard.com (85-76-16-252-nat.elisa-mobile.fi [85.76.16.252]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id E91CC9D5; Fri, 12 Apr 2024 21:07:10 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1712948831; bh=iBuwmavZMJ5jpcg8mNizkJ/zoPhJeyREETJcIjhK4kI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XgTk8cbI8ThLuCJGf33KEMnnDrD3qMeOmYuZovRl16iMUkwZzTNQ1A+NgqeA1hZf2 dVUAjAmECvHWBFAEiMwlzSOxRd5Uis+ecVEHD3IiYZgndaqCaaBvJwrHgWf/q1fWhw pjSQtjK4AV/jIW8p3KbcRD4zVhkLyQ2iJyyxBYuA= Date: Fri, 12 Apr 2024 22:07:46 +0300 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org, tomi.valkeinen@ideasonboard.com, bingbu.cao@intel.com, hongju.wang@intel.com, hverkuil@xs4all.nl, Andrey Konovalov , Jacopo Mondi , Dmitry Perchanov , "Ng, Khai Wen" , Alain Volmat Subject: Re: [PATCH v8 23/38] media: uapi: ccs: Add media bus code for MIPI CCS embedded data Message-ID: <20240412190746.GO31122@pendragon.ideasonboard.com> References: <20240313072516.241106-1-sakari.ailus@linux.intel.com> <20240313072516.241106-24-sakari.ailus@linux.intel.com> <20240321164914.GD9582@pendragon.ideasonboard.com> Precedence: bulk X-Mailing-List: linux-media@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: Hi Sakari, On Thu, Apr 11, 2024 at 09:04:47AM +0000, Sakari Ailus wrote: > On Thu, Mar 21, 2024 at 06:49:14PM +0200, Laurent Pinchart wrote: > > On Wed, Mar 13, 2024 at 09:25:01AM +0200, Sakari Ailus wrote: > > > Add new MIPI CCS embedded data media bus code > > > (MEDIA_BUS_FMT_CCS_EMBEDDED). > > > > > > Signed-off-by: Sakari Ailus > > > --- > > > .../media/v4l/subdev-formats.rst | 28 +++++++++++++++++++ > > > include/uapi/linux/media-bus-format.h | 3 ++ > > > 2 files changed, 31 insertions(+) > > > > > > diff --git a/Documentation/userspace-api/media/v4l/subdev-formats.rst b/Documentation/userspace-api/media/v4l/subdev-formats.rst > > > index cbd475f7cae9..c8f982411e70 100644 > > > --- a/Documentation/userspace-api/media/v4l/subdev-formats.rst > > > +++ b/Documentation/userspace-api/media/v4l/subdev-formats.rst > > > @@ -8564,3 +8564,31 @@ and finally the bit number in subscript. "X" indicates a padding bit. > > > - X > > > - X > > > - X > > > + > > > +.. _MEDIA-BUS-FMT-CCS-EMBEDDED: > > > + > > > +MIPI CCS Embedded Data Formats > > > +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > > + > > > +`MIPI CCS `_ defines a > > > +metadata format for sensor embedded data, which is used to store the register > > > +configuration used for capturing a given frame. The format is defined in the CCS > > > +specification. The media bus code for this format is > > > +``MEDIA_BUS_FMT_CCS_EMBEDDED``. > > > + > > > +The CCS embedded data format definition includes three levels: > > > + > > > +1. Padding within CSI-2 bus :ref:`Data unit ` as > > > > s/Data unit/Data Unit/ > > Yes. > > > > + documented in the MIPI CCS specification. > > > + > > > +2. The tagged data format as documented in the MIPI CCS specification. > > > + > > > +3. Register addresses and register documentation as documented in the MIPI CCS > > > + specification. > > > + > > > +The format definition shall be used only by devices that fulfill all three > > > +levels above. > > > > Hmmmm... Do we need to mandate level 3 ? There are lots of sensors that > > comply with the first two levels but have their own register set. Would > > you like a sensor-specific embedded data format for each of them ? If > > so, how would we document it without essentially copying the datasheet ? > > You could refer to the datasheet if it's publicly available. What if it's not ? How would you expect documentation to be organized ? Will we then end up adding one media bus code per sensor ? > The CCS static data format is meaningful only for accessing (level 1) and > parsing (level 2) the data without knowing its meaning, which is the most > important aspect. The user space will need to know the meaning of the data > and can additionally select the same data unpacker than for CCS and > possibly also the CCS data parser if applicable. > > The user space should especially not have to have a list of CCS-compliant > sensors which would become necessary, should we skip on the 3rd level > requirement here. > > > > + > > > +This mbus code are only used for "2-byte simplified tagged data format" (code > > > +0xa) but their use may be extended further in the future, to cover other CCS > > > +embedded data format codes. > > > diff --git a/include/uapi/linux/media-bus-format.h b/include/uapi/linux/media-bus-format.h > > > index d4c1d991014b..03f7e9ab517b 100644 > > > --- a/include/uapi/linux/media-bus-format.h > > > +++ b/include/uapi/linux/media-bus-format.h > > > @@ -183,4 +183,7 @@ > > > #define MEDIA_BUS_FMT_META_20 0x8006 > > > #define MEDIA_BUS_FMT_META_24 0x8007 > > > > > > +/* Specific metadata formats. Next is 0x9002. */ > > > +#define MEDIA_BUS_FMT_CCS_EMBEDDED 0x9001 > > > + > > > #endif /* __LINUX_MEDIA_BUS_FORMAT_H */ -- Regards, Laurent Pinchart