![Mauro Carvalho Chehab](/assets/img/avatar_default.png)
All Documentation files outside the uAPI are all licensed with, at least, GPL 2.0. So, mark them as such. The ondes at media/uapi are at least GFDL 1.1+. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
285 lines
10 KiB
ReStructuredText
285 lines
10 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
.. include:: <isonum.txt>
|
|
|
|
OMAP 3 Image Signal Processor (ISP) driver
|
|
==========================================
|
|
|
|
Copyright |copy| 2010 Nokia Corporation
|
|
|
|
Copyright |copy| 2009 Texas Instruments, Inc.
|
|
|
|
Contacts: Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
|
|
Sakari Ailus <sakari.ailus@iki.fi>, David Cohen <dacohen@gmail.com>
|
|
|
|
|
|
Introduction
|
|
------------
|
|
|
|
This file documents the Texas Instruments OMAP 3 Image Signal Processor (ISP)
|
|
driver located under drivers/media/platform/omap3isp. The original driver was
|
|
written by Texas Instruments but since that it has been rewritten (twice) at
|
|
Nokia.
|
|
|
|
The driver has been successfully used on the following versions of OMAP 3:
|
|
|
|
- 3430
|
|
- 3530
|
|
- 3630
|
|
|
|
The driver implements V4L2, Media controller and v4l2_subdev interfaces.
|
|
Sensor, lens and flash drivers using the v4l2_subdev interface in the kernel
|
|
are supported.
|
|
|
|
|
|
Split to subdevs
|
|
----------------
|
|
|
|
The OMAP 3 ISP is split into V4L2 subdevs, each of the blocks inside the ISP
|
|
having one subdev to represent it. Each of the subdevs provide a V4L2 subdev
|
|
interface to userspace.
|
|
|
|
- OMAP3 ISP CCP2
|
|
- OMAP3 ISP CSI2a
|
|
- OMAP3 ISP CCDC
|
|
- OMAP3 ISP preview
|
|
- OMAP3 ISP resizer
|
|
- OMAP3 ISP AEWB
|
|
- OMAP3 ISP AF
|
|
- OMAP3 ISP histogram
|
|
|
|
Each possible link in the ISP is modelled by a link in the Media controller
|
|
interface. For an example program see [#f2]_.
|
|
|
|
|
|
Controlling the OMAP 3 ISP
|
|
--------------------------
|
|
|
|
In general, the settings given to the OMAP 3 ISP take effect at the beginning
|
|
of the following frame. This is done when the module becomes idle during the
|
|
vertical blanking period on the sensor. In memory-to-memory operation the pipe
|
|
is run one frame at a time. Applying the settings is done between the frames.
|
|
|
|
All the blocks in the ISP, excluding the CSI-2 and possibly the CCP2 receiver,
|
|
insist on receiving complete frames. Sensors must thus never send the ISP
|
|
partial frames.
|
|
|
|
Autoidle does have issues with some ISP blocks on the 3430, at least.
|
|
Autoidle is only enabled on 3630 when the omap3isp module parameter autoidle
|
|
is non-zero.
|
|
|
|
|
|
Events
|
|
------
|
|
|
|
The OMAP 3 ISP driver does support the V4L2 event interface on CCDC and
|
|
statistics (AEWB, AF and histogram) subdevs.
|
|
|
|
The CCDC subdev produces V4L2_EVENT_FRAME_SYNC type event on HS_VS
|
|
interrupt which is used to signal frame start. Earlier version of this
|
|
driver used V4L2_EVENT_OMAP3ISP_HS_VS for this purpose. The event is
|
|
triggered exactly when the reception of the first line of the frame starts
|
|
in the CCDC module. The event can be subscribed on the CCDC subdev.
|
|
|
|
(When using parallel interface one must pay account to correct configuration
|
|
of the VS signal polarity. This is automatically correct when using the serial
|
|
receivers.)
|
|
|
|
Each of the statistics subdevs is able to produce events. An event is
|
|
generated whenever a statistics buffer can be dequeued by a user space
|
|
application using the VIDIOC_OMAP3ISP_STAT_REQ IOCTL. The events available
|
|
are:
|
|
|
|
- V4L2_EVENT_OMAP3ISP_AEWB
|
|
- V4L2_EVENT_OMAP3ISP_AF
|
|
- V4L2_EVENT_OMAP3ISP_HIST
|
|
|
|
The type of the event data is struct omap3isp_stat_event_status for these
|
|
ioctls. If there is an error calculating the statistics, there will be an
|
|
event as usual, but no related statistics buffer. In this case
|
|
omap3isp_stat_event_status.buf_err is set to non-zero.
|
|
|
|
|
|
Private IOCTLs
|
|
--------------
|
|
|
|
The OMAP 3 ISP driver supports standard V4L2 IOCTLs and controls where
|
|
possible and practical. Much of the functions provided by the ISP, however,
|
|
does not fall under the standard IOCTLs --- gamma tables and configuration of
|
|
statistics collection are examples of such.
|
|
|
|
In general, there is a private ioctl for configuring each of the blocks
|
|
containing hardware-dependent functions.
|
|
|
|
The following private IOCTLs are supported:
|
|
|
|
- VIDIOC_OMAP3ISP_CCDC_CFG
|
|
- VIDIOC_OMAP3ISP_PRV_CFG
|
|
- VIDIOC_OMAP3ISP_AEWB_CFG
|
|
- VIDIOC_OMAP3ISP_HIST_CFG
|
|
- VIDIOC_OMAP3ISP_AF_CFG
|
|
- VIDIOC_OMAP3ISP_STAT_REQ
|
|
- VIDIOC_OMAP3ISP_STAT_EN
|
|
|
|
The parameter structures used by these ioctls are described in
|
|
include/linux/omap3isp.h. The detailed functions of the ISP itself related to
|
|
a given ISP block is described in the Technical Reference Manuals (TRMs) ---
|
|
see the end of the document for those.
|
|
|
|
While it is possible to use the ISP driver without any use of these private
|
|
IOCTLs it is not possible to obtain optimal image quality this way. The AEWB,
|
|
AF and histogram modules cannot be used without configuring them using the
|
|
appropriate private IOCTLs.
|
|
|
|
|
|
CCDC and preview block IOCTLs
|
|
-----------------------------
|
|
|
|
The VIDIOC_OMAP3ISP_CCDC_CFG and VIDIOC_OMAP3ISP_PRV_CFG IOCTLs are used to
|
|
configure, enable and disable functions in the CCDC and preview blocks,
|
|
respectively. Both IOCTLs control several functions in the blocks they
|
|
control. VIDIOC_OMAP3ISP_CCDC_CFG IOCTL accepts a pointer to struct
|
|
omap3isp_ccdc_update_config as its argument. Similarly VIDIOC_OMAP3ISP_PRV_CFG
|
|
accepts a pointer to struct omap3isp_prev_update_config. The definition of
|
|
both structures is available in [#f1]_.
|
|
|
|
The update field in the structures tells whether to update the configuration
|
|
for the specific function and the flag tells whether to enable or disable the
|
|
function.
|
|
|
|
The update and flag bit masks accept the following values. Each separate
|
|
functions in the CCDC and preview blocks is associated with a flag (either
|
|
disable or enable; part of the flag field in the structure) and a pointer to
|
|
configuration data for the function.
|
|
|
|
Valid values for the update and flag fields are listed here for
|
|
VIDIOC_OMAP3ISP_CCDC_CFG. Values may be or'ed to configure more than one
|
|
function in the same IOCTL call.
|
|
|
|
- OMAP3ISP_CCDC_ALAW
|
|
- OMAP3ISP_CCDC_LPF
|
|
- OMAP3ISP_CCDC_BLCLAMP
|
|
- OMAP3ISP_CCDC_BCOMP
|
|
- OMAP3ISP_CCDC_FPC
|
|
- OMAP3ISP_CCDC_CULL
|
|
- OMAP3ISP_CCDC_CONFIG_LSC
|
|
- OMAP3ISP_CCDC_TBL_LSC
|
|
|
|
The corresponding values for the VIDIOC_OMAP3ISP_PRV_CFG are here:
|
|
|
|
- OMAP3ISP_PREV_LUMAENH
|
|
- OMAP3ISP_PREV_INVALAW
|
|
- OMAP3ISP_PREV_HRZ_MED
|
|
- OMAP3ISP_PREV_CFA
|
|
- OMAP3ISP_PREV_CHROMA_SUPP
|
|
- OMAP3ISP_PREV_WB
|
|
- OMAP3ISP_PREV_BLKADJ
|
|
- OMAP3ISP_PREV_RGB2RGB
|
|
- OMAP3ISP_PREV_COLOR_CONV
|
|
- OMAP3ISP_PREV_YC_LIMIT
|
|
- OMAP3ISP_PREV_DEFECT_COR
|
|
- OMAP3ISP_PREV_GAMMABYPASS
|
|
- OMAP3ISP_PREV_DRK_FRM_CAPTURE
|
|
- OMAP3ISP_PREV_DRK_FRM_SUBTRACT
|
|
- OMAP3ISP_PREV_LENS_SHADING
|
|
- OMAP3ISP_PREV_NF
|
|
- OMAP3ISP_PREV_GAMMA
|
|
|
|
The associated configuration pointer for the function may not be NULL when
|
|
enabling the function. When disabling a function the configuration pointer is
|
|
ignored.
|
|
|
|
|
|
Statistic blocks IOCTLs
|
|
-----------------------
|
|
|
|
The statistics subdevs do offer more dynamic configuration options than the
|
|
other subdevs. They can be enabled, disable and reconfigured when the pipeline
|
|
is in streaming state.
|
|
|
|
The statistics blocks always get the input image data from the CCDC (as the
|
|
histogram memory read isn't implemented). The statistics are dequeueable by
|
|
the user from the statistics subdev nodes using private IOCTLs.
|
|
|
|
The private IOCTLs offered by the AEWB, AF and histogram subdevs are heavily
|
|
reflected by the register level interface offered by the ISP hardware. There
|
|
are aspects that are purely related to the driver implementation and these are
|
|
discussed next.
|
|
|
|
VIDIOC_OMAP3ISP_STAT_EN
|
|
-----------------------
|
|
|
|
This private IOCTL enables/disables a statistic module. If this request is
|
|
done before streaming, it will take effect as soon as the pipeline starts to
|
|
stream. If the pipeline is already streaming, it will take effect as soon as
|
|
the CCDC becomes idle.
|
|
|
|
VIDIOC_OMAP3ISP_AEWB_CFG, VIDIOC_OMAP3ISP_HIST_CFG and VIDIOC_OMAP3ISP_AF_CFG
|
|
-----------------------------------------------------------------------------
|
|
|
|
Those IOCTLs are used to configure the modules. They require user applications
|
|
to have an in-depth knowledge of the hardware. Most of the fields explanation
|
|
can be found on OMAP's TRMs. The two following fields common to all the above
|
|
configure private IOCTLs require explanation for better understanding as they
|
|
are not part of the TRM.
|
|
|
|
omap3isp_[h3a_af/h3a_aewb/hist]\_config.buf_size:
|
|
|
|
The modules handle their buffers internally. The necessary buffer size for the
|
|
module's data output depends on the requested configuration. Although the
|
|
driver supports reconfiguration while streaming, it does not support a
|
|
reconfiguration which requires bigger buffer size than what is already
|
|
internally allocated if the module is enabled. It will return -EBUSY on this
|
|
case. In order to avoid such condition, either disable/reconfigure/enable the
|
|
module or request the necessary buffer size during the first configuration
|
|
while the module is disabled.
|
|
|
|
The internal buffer size allocation considers the requested configuration's
|
|
minimum buffer size and the value set on buf_size field. If buf_size field is
|
|
out of [minimum, maximum] buffer size range, it's clamped to fit in there.
|
|
The driver then selects the biggest value. The corrected buf_size value is
|
|
written back to user application.
|
|
|
|
omap3isp_[h3a_af/h3a_aewb/hist]\_config.config_counter:
|
|
|
|
As the configuration doesn't take effect synchronously to the request, the
|
|
driver must provide a way to track this information to provide more accurate
|
|
data. After a configuration is requested, the config_counter returned to user
|
|
space application will be an unique value associated to that request. When
|
|
user application receives an event for buffer availability or when a new
|
|
buffer is requested, this config_counter is used to match a buffer data and a
|
|
configuration.
|
|
|
|
VIDIOC_OMAP3ISP_STAT_REQ
|
|
------------------------
|
|
|
|
Send to user space the oldest data available in the internal buffer queue and
|
|
discards such buffer afterwards. The field omap3isp_stat_data.frame_number
|
|
matches with the video buffer's field_count.
|
|
|
|
|
|
Technical reference manuals (TRMs) and other documentation
|
|
----------------------------------------------------------
|
|
|
|
OMAP 3430 TRM:
|
|
<URL:http://focus.ti.com/pdfs/wtbu/OMAP34xx_ES3.1.x_PUBLIC_TRM_vZM.zip>
|
|
Referenced 2011-03-05.
|
|
|
|
OMAP 35xx TRM:
|
|
<URL:http://www.ti.com/litv/pdf/spruf98o> Referenced 2011-03-05.
|
|
|
|
OMAP 3630 TRM:
|
|
<URL:http://focus.ti.com/pdfs/wtbu/OMAP36xx_ES1.x_PUBLIC_TRM_vQ.zip>
|
|
Referenced 2011-03-05.
|
|
|
|
DM 3730 TRM:
|
|
<URL:http://www.ti.com/litv/pdf/sprugn4h> Referenced 2011-03-06.
|
|
|
|
|
|
References
|
|
----------
|
|
|
|
.. [#f1] include/linux/omap3isp.h
|
|
|
|
.. [#f2] http://git.ideasonboard.org/?p=media-ctl.git;a=summary
|