diff options
Diffstat (limited to 'Documentation/media')
| -rw-r--r-- | Documentation/media/v4l-drivers/imx-uapi.rst | 125 | ||||
| -rw-r--r-- | Documentation/media/v4l-drivers/imx.rst | 88 | ||||
| -rw-r--r-- | Documentation/media/v4l-drivers/index.rst | 1 |
3 files changed, 128 insertions, 86 deletions
diff --git a/Documentation/media/v4l-drivers/imx-uapi.rst b/Documentation/media/v4l-drivers/imx-uapi.rst new file mode 100644 index 000000000000..8d47712dea9f --- /dev/null +++ b/Documentation/media/v4l-drivers/imx-uapi.rst @@ -0,0 +1,125 @@ +.. SPDX-License-Identifier: GPL-2.0 + +========================= +i.MX Video Capture Driver +========================= + +Events +====== + +.. _imx_api_ipuX_csiY: + +ipuX_csiY +--------- + +This subdev can generate the following event when enabling the second +IDMAC source pad: + +- V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR + +The user application can subscribe to this event from the ipuX_csiY +subdev node. This event is generated by the Frame Interval Monitor +(see below for more on the FIM). + +Controls +======== + +.. _imx_api_FIM: + +Frame Interval Monitor in ipuX_csiY +----------------------------------- + +The adv718x decoders can occasionally send corrupt fields during +NTSC/PAL signal re-sync (too little or too many video lines). When +this happens, the IPU triggers a mechanism to re-establish vertical +sync by adding 1 dummy line every frame, which causes a rolling effect +from image to image, and can last a long time before a stable image is +recovered. Or sometimes the mechanism doesn't work at all, causing a +permanent split image (one frame contains lines from two consecutive +captured images). + +From experiment it was found that during image rolling, the frame +intervals (elapsed time between two EOF's) drop below the nominal +value for the current standard, by about one frame time (60 usec), +and remain at that value until rolling stops. + +While the reason for this observation isn't known (the IPU dummy +line mechanism should show an increase in the intervals by 1 line +time every frame, not a fixed value), we can use it to detect the +corrupt fields using a frame interval monitor. If the FIM detects a +bad frame interval, the ipuX_csiY subdev will send the event +V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR. Userland can register with +the FIM event notification on the ipuX_csiY subdev device node. +Userland can issue a streaming restart when this event is received +to correct the rolling/split image. + +The ipuX_csiY subdev includes custom controls to tweak some dials for +FIM. If one of these controls is changed during streaming, the FIM will +be reset and will continue at the new settings. + +- V4L2_CID_IMX_FIM_ENABLE + +Enable/disable the FIM. + +- V4L2_CID_IMX_FIM_NUM + +How many frame interval measurements to average before comparing against +the nominal frame interval reported by the sensor. This can reduce noise +caused by interrupt latency. + +- V4L2_CID_IMX_FIM_TOLERANCE_MIN + +If the averaged intervals fall outside nominal by this amount, in +microseconds, the V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR event is sent. + +- V4L2_CID_IMX_FIM_TOLERANCE_MAX + +If any intervals are higher than this value, those samples are +discarded and do not enter into the average. This can be used to +discard really high interval errors that might be due to interrupt +latency from high system load. + +- V4L2_CID_IMX_FIM_NUM_SKIP + +How many frames to skip after a FIM reset or stream restart before +FIM begins to average intervals. + +- V4L2_CID_IMX_FIM_ICAP_CHANNEL / V4L2_CID_IMX_FIM_ICAP_EDGE + +These controls will configure an input capture channel as the method +for measuring frame intervals. This is superior to the default method +of measuring frame intervals via EOF interrupt, since it is not subject +to uncertainty errors introduced by interrupt latency. + +Input capture requires hardware support. A VSYNC signal must be routed +to one of the i.MX6 input capture channel pads. + +V4L2_CID_IMX_FIM_ICAP_CHANNEL configures which i.MX6 input capture +channel to use. This must be 0 or 1. + +V4L2_CID_IMX_FIM_ICAP_EDGE configures which signal edge will trigger +input capture events. By default the input capture method is disabled +with a value of IRQ_TYPE_NONE. Set this control to IRQ_TYPE_EDGE_RISING, +IRQ_TYPE_EDGE_FALLING, or IRQ_TYPE_EDGE_BOTH to enable input capture, +triggered on the given signal edge(s). + +When input capture is disabled, frame intervals will be measured via +EOF interrupt. + + +File list +--------- + +drivers/staging/media/imx/ +include/media/imx.h +include/linux/imx-media.h + + +Authors +------- + +- Steve Longerbeam <steve_longerbeam@mentor.com> +- Philipp Zabel <kernel@pengutronix.de> +- Russell King <linux@armlinux.org.uk> + +Copyright (C) 2012-2017 Mentor Graphics Inc. diff --git a/Documentation/media/v4l-drivers/imx.rst b/Documentation/media/v4l-drivers/imx.rst index 1246573c1019..3182951c7651 100644 --- a/Documentation/media/v4l-drivers/imx.rst +++ b/Documentation/media/v4l-drivers/imx.rst @@ -191,14 +191,7 @@ or unqualified interlaced). The capture interface will enforce the same field order as the source pad field order (interlaced-bt if source pad is seq-bt, interlaced-tb if source pad is seq-tb). -This subdev can generate the following event when enabling the second -IDMAC source pad: - -- V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR - -The user application can subscribe to this event from the ipuX_csiY -subdev node. This event is generated by the Frame Interval Monitor -(see below for more on the FIM). +For events produced by ipuX_csiY, see ref:`imx_api_ipuX_csiY`. Cropping in ipuX_csiY --------------------- @@ -247,84 +240,7 @@ rate by half at the IDMAC output source pad: Frame Interval Monitor in ipuX_csiY ----------------------------------- -The adv718x decoders can occasionally send corrupt fields during -NTSC/PAL signal re-sync (too little or too many video lines). When -this happens, the IPU triggers a mechanism to re-establish vertical -sync by adding 1 dummy line every frame, which causes a rolling effect -from image to image, and can last a long time before a stable image is -recovered. Or sometimes the mechanism doesn't work at all, causing a -permanent split image (one frame contains lines from two consecutive -captured images). - -From experiment it was found that during image rolling, the frame -intervals (elapsed time between two EOF's) drop below the nominal -value for the current standard, by about one frame time (60 usec), -and remain at that value until rolling stops. - -While the reason for this observation isn't known (the IPU dummy -line mechanism should show an increase in the intervals by 1 line -time every frame, not a fixed value), we can use it to detect the -corrupt fields using a frame interval monitor. If the FIM detects a -bad frame interval, the ipuX_csiY subdev will send the event -V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR. Userland can register with -the FIM event notification on the ipuX_csiY subdev device node. -Userland can issue a streaming restart when this event is received -to correct the rolling/split image. - -The ipuX_csiY subdev includes custom controls to tweak some dials for -FIM. If one of these controls is changed during streaming, the FIM will -be reset and will continue at the new settings. - -- V4L2_CID_IMX_FIM_ENABLE - -Enable/disable the FIM. - -- V4L2_CID_IMX_FIM_NUM - -How many frame interval measurements to average before comparing against -the nominal frame interval reported by the sensor. This can reduce noise -caused by interrupt latency. - -- V4L2_CID_IMX_FIM_TOLERANCE_MIN - -If the averaged intervals fall outside nominal by this amount, in -microseconds, the V4L2_EVENT_IMX_FRAME_INTERVAL_ERROR event is sent. - -- V4L2_CID_IMX_FIM_TOLERANCE_MAX - -If any intervals are higher than this value, those samples are -discarded and do not enter into the average. This can be used to -discard really high interval errors that might be due to interrupt -latency from high system load. - -- V4L2_CID_IMX_FIM_NUM_SKIP - -How many frames to skip after a FIM reset or stream restart before -FIM begins to average intervals. - -- V4L2_CID_IMX_FIM_ICAP_CHANNEL -- V4L2_CID_IMX_FIM_ICAP_EDGE - -These controls will configure an input capture channel as the method -for measuring frame intervals. This is superior to the default method -of measuring frame intervals via EOF interrupt, since it is not subject -to uncertainty errors introduced by interrupt latency. - -Input capture requires hardware support. A VSYNC signal must be routed -to one of the i.MX6 input capture channel pads. - -V4L2_CID_IMX_FIM_ICAP_CHANNEL configures which i.MX6 input capture -channel to use. This must be 0 or 1. - -V4L2_CID_IMX_FIM_ICAP_EDGE configures which signal edge will trigger -input capture events. By default the input capture method is disabled -with a value of IRQ_TYPE_NONE. Set this control to IRQ_TYPE_EDGE_RISING, -IRQ_TYPE_EDGE_FALLING, or IRQ_TYPE_EDGE_BOTH to enable input capture, -triggered on the given signal edge(s). - -When input capture is disabled, frame intervals will be measured via -EOF interrupt. - +See ref:`imx_api_FIM`. ipuX_vdic --------- diff --git a/Documentation/media/v4l-drivers/index.rst b/Documentation/media/v4l-drivers/index.rst index 364c65ea86fb..67665a8abe02 100644 --- a/Documentation/media/v4l-drivers/index.rst +++ b/Documentation/media/v4l-drivers/index.rst @@ -75,5 +75,6 @@ For more details see the file COPYING in the source distribution of Linux. vimc-devel cx2341x-uapi + imx-uapi meye-uapi omap3isp-uapi |