From: Todor Tomov <todor.tomov@linaro.org>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: mchehab@kernel.org, hans.verkuil@cisco.com,
s.nawrocki@samsung.com, sakari.ailus@iki.fi,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v4 04/21] doc: media/v4l-drivers: Add Qualcomm Camera Subsystem driver document
Date: Fri, 18 Aug 2017 10:53:58 +0300 [thread overview]
Message-ID: <5d7d59c0-6306-ca14-fabe-d6789f6bfd5d@linaro.org> (raw)
In-Reply-To: <1ee25592-63c7-0da8-c58f-a82e0b5d692f@xs4all.nl>
Hi Hans,
On 18.08.2017 10:45, Hans Verkuil wrote:
> Hi Todor,
>
> A few small comments below:
>
> On 08/08/2017 03:30 PM, Todor Tomov wrote:
>> Add a document to describe Qualcomm Camera Subsystem driver.
>>
>> Signed-off-by: Todor Tomov <todor.tomov@linaro.org>
>> ---
>> Documentation/media/v4l-drivers/qcom_camss.rst | 124 +++++++++++++++++++++++++
>> 1 file changed, 124 insertions(+)
>> create mode 100644 Documentation/media/v4l-drivers/qcom_camss.rst
>>
>> diff --git a/Documentation/media/v4l-drivers/qcom_camss.rst b/Documentation/media/v4l-drivers/qcom_camss.rst
>> new file mode 100644
>> index 0000000..4707ea7
>> --- /dev/null
>> +++ b/Documentation/media/v4l-drivers/qcom_camss.rst
>> @@ -0,0 +1,124 @@
>> +.. include:: <isonum.txt>
>> +
>> +Qualcomm Camera Subsystem driver
>> +================================
>> +
>> +Introduction
>> +------------
>> +
>> +This file documents the Qualcomm Camera Subsystem driver located under
>> +drivers/media/platform/qcom/camss-8x16.
>> +
>> +The current version of the driver supports the Camera Subsystem found on
>> +Qualcomm MSM8916 and APQ8016 processors.
>> +
>> +The driver implements V4L2, Media controller and V4L2 subdev interfaces.
>> +Camera sensor using V4L2 subdev interface in the kernel is supported.
>> +
>> +The driver is implemented using as a reference the Qualcomm Camera Subsystem
>> +driver for Android as found in Code Aurora [#f1]_.
>> +
>> +
>> +Qualcomm Camera Subsystem hardware
>> +----------------------------------
>> +
>> +The Camera Subsystem hardware found on 8x16 processors and supported by the
>> +driver consists of:
>> +
>> +- 2 CSIPHY modules. They handle the Physical layer of the CSI2 receivers.
>> + A separate camera sensor can be connected to each of the CSIPHY module;
>> +- 2 CSID (CSI Decoder) modules. They handle the Protocol and Application layer
>> + of the CSI2 receivers. A CSID can decode data stream from any of the CSIPHY.
>> + Each CSID also contains a TG (Test Generator) block which can generate
>> + artificial input data for test purposes;
>> +- ISPIF (ISP Interface) module. Handles the routing of the data streams from
>> + the CSIDs to the inputs of the VFE;
>> +- VFE (Video Front End) module. Contains a pipeline of image processing hardware
>> + blocks. The VFE has different input interfaces. The PIX input interface feeds
>> + the input data to the image processing pipeline. Three RDI input interfaces
>> + bypass the image processing pipeline. The VFE also contains the AXI bus
>> + interface which writes the output data to memory.
>
> Can you explain what PIX and RDI stand for?
>
> I would also think it is a good idea to add a comment at the top of the various
> subdev sources that say a bit more than just "CSID Module".
>
> A simple "CSID (CSI Decoder) Module" is enough. Just so the reader knows what
> it is all about.
>
> Otherwise I don't have any more comments about this series.
>
> I don't need a v5 for this, if you can just post one patch for this documentation
> and one patch improving the source comments as described above, then that's
> fine with me.
Thank you for the review again.
I'll post two additional patches to add explanations of the abbreviations.
>
> Regards,
>
> Hans
>
>> +
>> +
>> +Supported functionality
>> +-----------------------
>> +
>> +The current version of the driver supports:
>> +
>> +- input from camera sensor via CSIPHY;
>> +- generation of test input data by the TG in CSID;
>> +- raw dump of the input data to memory. RDI interface of VFE is supported.
>> + PIX interface (ISP processing, statistics engines, resize/crop, format
>> + conversion) is not supported in the current version;
>> +- concurrent and independent usage of two data inputs - could be camera sensors
>> + and/or TG.
>> +
>> +
>> +Driver Architecture and Design
>> +------------------------------
>> +
>> +The driver implements the V4L2 subdev interface. With the goal to model the
>> +hardware links between the modules and to expose a clean, logical and usable
>> +interface, the driver is split into V4L2 sub-devices as follows:
>> +
>> +- 2 CSIPHY sub-devices - each CSIPHY is represented by a single sub-device;
>> +- 2 CSID sub-devices - each CSID is represented by a single sub-device;
>> +- 2 ISPIF sub-devices - ISPIF is represented by a number of sub-devices equal
>> + to the number of CSID sub-devices;
>> +- 3 VFE sub-devices - VFE is represented by a number of sub-devices equal to
>> + the number of RDI input interfaces.
>> +
>> +The considerations to split the driver in this particular way are as follows:
>> +
>> +- representing CSIPHY and CSID modules by a separate sub-device for each module
>> + allows to model the hardware links between these modules;
>> +- representing VFE by a separate sub-devices for each RDI input interface allows
>> + to use the three RDI interfaces concurently and independently as this is
>> + supported by the hardware;
>> +- representing ISPIF by a number of sub-devices equal to the number of CSID
>> + sub-devices allows to create linear media controller pipelines when using two
>> + cameras simultaneously. This avoids branches in the pipelines which otherwise
>> + will require a) userspace and b) media framework (e.g. power on/off
>> + operations) to make assumptions about the data flow from a sink pad to a
>> + source pad on a single media entity.
>> +
>> +Each VFE sub-device is linked to a separate video device node.
>> +
>> +The complete list of the media entities (V4L2 sub-devices and video device
>> +nodes) is as follows:
>> +
>> +- msm_csiphy0
>> +- msm_csiphy1
>> +- msm_csid0
>> +- msm_csid1
>> +- msm_ispif0
>> +- msm_ispif1
>> +- msm_vfe0_rdi0
>> +- msm_vfe0_video0
>> +- msm_vfe0_rdi1
>> +- msm_vfe0_video1
>> +- msm_vfe0_rdi2
>> +- msm_vfe0_video2
>> +
>> +
>> +Implementation
>> +--------------
>> +
>> +Runtime configuration of the hardware (updating settings while streaming) is
>> +not required to implement the currently supported functionality. The complete
>> +configuration on each hardware module is applied on STREAMON ioctl based on
>> +the current active media links, formats and controls set.
>> +
>> +
>> +Documentation
>> +-------------
>> +
>> +APQ8016 Specification:
>> +https://developer.qualcomm.com/download/sd410/snapdragon-410-processor-device-specification.pdf
>> +Referenced 2016-11-24.
>> +
>> +
>> +References
>> +----------
>> +
>> +.. [#f1] https://source.codeaurora.org/quic/la/kernel/msm-3.10/
>>
>
--
Best regards,
Todor Tomov
next prev parent reply other threads:[~2017-08-18 7:54 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-08 13:29 [PATCH v4 00/21] Qualcomm 8x16 Camera Subsystem driver Todor Tomov
2017-08-08 13:29 ` [PATCH v4 01/21] v4l: Add packed Bayer raw12 pixel formats Todor Tomov
2017-08-08 13:29 ` [PATCH v4 02/21] dt-bindings: media: Binding document for Qualcomm Camera subsystem driver Todor Tomov
2017-08-08 13:30 ` [PATCH v4 03/21] MAINTAINERS: Add " Todor Tomov
2017-08-08 13:30 ` [PATCH v4 04/21] doc: media/v4l-drivers: Add Qualcomm Camera Subsystem driver document Todor Tomov
2017-08-18 7:45 ` Hans Verkuil
2017-08-18 7:53 ` Todor Tomov [this message]
2017-08-25 14:10 ` Daniel Mack
2017-08-28 7:10 ` Todor Tomov
2017-08-29 17:02 ` Daniel Mack
2017-10-16 15:01 ` Daniel Mack
2017-10-25 12:07 ` Todor Tomov
2017-10-25 12:18 ` Daniel Mack
2017-08-08 13:30 ` [PATCH v4 05/21] media: camss: Add CSIPHY files Todor Tomov
2017-08-08 13:30 ` [PATCH v4 06/21] media: camss: Add CSID files Todor Tomov
2017-08-08 13:30 ` [PATCH v4 07/21] media: camss: Add ISPIF files Todor Tomov
2017-08-08 13:30 ` [PATCH v4 08/21] media: camss: Add VFE files Todor Tomov
2017-08-08 13:30 ` [PATCH v4 09/21] media: camss: Add files which handle the video device nodes Todor Tomov
2017-08-08 14:44 ` Sakari Ailus
2017-08-08 13:30 ` [PATCH v4 10/21] media: camms: Add core files Todor Tomov
2017-08-08 13:30 ` [PATCH v4 11/21] media: camss: Enable building Todor Tomov
2017-08-08 13:30 ` [PATCH v4 12/21] camss: vfe: Format conversion support using PIX interface Todor Tomov
2017-09-10 9:58 ` Geert Uytterhoeven
2017-09-11 6:56 ` Todor Tomov
2017-09-11 7:45 ` Geert Uytterhoeven
2017-08-08 13:30 ` [PATCH v4 13/21] doc: media/v4l-drivers: Qualcomm Camera Subsystem - PIX Interface Todor Tomov
2017-08-08 13:30 ` [PATCH v4 14/21] camss: vfe: Support for frame padding Todor Tomov
2017-08-08 13:30 ` [PATCH v4 15/21] camss: vfe: Add interface for scaling Todor Tomov
2017-08-08 13:30 ` [PATCH v4 16/21] camss: vfe: Configure scaler module in VFE Todor Tomov
2017-08-08 13:30 ` [PATCH v4 17/21] camss: vfe: Add interface for cropping Todor Tomov
2017-08-08 13:30 ` [PATCH v4 18/21] camss: vfe: Configure crop module in VFE Todor Tomov
2017-08-08 13:30 ` [PATCH v4 19/21] doc: media/v4l-drivers: Qualcomm Camera Subsystem - Scale and crop Todor Tomov
2017-08-08 13:30 ` [PATCH v4 20/21] camss: Use optimal clock frequency rates Todor Tomov
2017-08-08 13:30 ` [PATCH v4 21/21] doc: media/v4l-drivers: Qualcomm Camera Subsystem - Media graph Todor Tomov
2017-08-08 14:53 ` [PATCH v4 00/21] Qualcomm 8x16 Camera Subsystem driver Sakari Ailus
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