Guennadi,
No, subdevice drivers, using the mediabus API, know nothing about fourcc
codes, that belongs to the user side of the pixel format handling API. The
path, e.g., for the VIDIOC_S_FMT ioctl() is
soc_camera.c::soc_camera_s_fmt_vid_cap(V4L2_PIX_FMT_GREY)
sh_mobile_ceu_camera.c::sh_mobile_ceu_set_fmt(V4L2_PIX_FMT_GREY)
the latter will try to call the .s_mbus_fmt() method from
soc_camera_platform.c and will fail, because that got lost during the
v4l2-subdev conversion, which is a bug and has to be fixed, patch welcome.
In trying to figure out how to best patch the lacking .s_mbus_fmt() option,
I setup:
static struct v4l2_subdev_video_ops platform_subdev_video_ops = {
.s_stream = soc_camera_platform_s_stream,
.try_mbus_fmt = soc_camera_platform_try_fmt,
.enum_mbus_fmt = soc_camera_platform_enum_fmt,
.g_mbus_fmt = soc_camera_platform_try_fmt,
.s_mbus_fmt = soc_camera_platform_try_fmt,
};
Is there any reason I can't reuse a slightly modified "try_fmt" function to
do the set?
Here's what I currently have:
static int soc_camera_platform_try_fmt(struct v4l2_subdev *sd,
struct v4l2_mbus_framefmt *mf)
{
struct soc_camera_platform_info *p = v4l2_get_subdevdata(sd);
mf->width = p->format.width;
mf->height = p->format.height;
mf->code = p->format.code;
mf->colorspace = p->format.colorspace;
mf->field = p->format.field;
return 0;
}
But regardless of how I set this structure up, I don't see any direct
support
for a Grayscale mode data capture in the ceu driver. For example,
"sh_mobile_ceu_set_bus_param" does not contain V4L2_PIX_FMT_GREY in its
list
of fourcc formats. Yet based on the 7724 hardware manual, and from the
information I have received from Renesas, I'm not seeing any reason why
this
format should not be supported.
Is grayscale somehow supported under the current CEU driver?
Sure, that's what the pass-through mode with a standard soc-mbus format
conversion is for (see soc_mbus_get_fmtdesc()).
After thoroughly reviewing the register documentation for the CEU, there are
several changes I'm implementing. This camera doesn't put out any color
sampling, so the registers in the CEU must be configured to use "image data
fetch" mode.
Where I'm currently struggling is in "sh_mobile_ceu_set_fmt" where the call
is made to "soc_camera_xlate_by_fourcc(icd, pixfmt)".
I'm still trying to figure out where the data needs to be defined that
eventually becomes "pixfmt". Should this be setup as an additional
parameter from inside "soc_camera_platform_try_fmt"?
What's the relationship between "v4l2_format" and "v4l2_mbus_framefmt"?
Thank you,
Charles Krebs, Embedded Solutions Developer
The Realtime Group
--------------------------------------------------
From: "Guennadi Liakhovetski" <g.liakhovetski@xxxxxx>
Sent: Tuesday, May 04, 2010 1:43 AM
To: "Charles D. Krebs" <ckrebs@xxxxxxxxxxxxxxxxxxxx>
Cc: "Linux Media Mailing List" <linux-media@xxxxxxxxxxxxxxx>; "Magnus Damm"
<magnus.damm@xxxxxxxxx>
Subject: Re: CEU / Camera Driver Question
Hi Charles
On Mon, 3 May 2010, Charles D. Krebs wrote:
Guennadi,
As per your recommendation I reviewed the "soc_camera_platform" driver,
and
have chosen to implement the new camera by simply modifying it.
Sure enough, I can boot up and properly register a device under
/dev/video0.
The camera provides 8-bit Grayscale data corresponding to pixel format
V4L2_PIX_FMT_GREY. I can't seem to find any example of a device driver
that
uses this format, so I've been taking my best guess as how to setup
"soc_camera_platform_info". So far I have:
static struct soc_camera_platform_info mycam_camera_info = {
.format_name = "GREY",
.format_depth = 8,
.format = {
.code = V4L2_MBUS_FMT_YUYV8_2X8_BE,
No, you should be using V4L2_MBUS_FMT_GREY8_1X8 for grey.
.colorspace = V4L2_COLORSPACE_JPEG,
.field = V4L2_FIELD_NONE,
.width = 320,
.height = 240,
},
.bus_param = SOCAM_PCLK_SAMPLE_RISING | SOCAM_HSYNC_ACTIVE_HIGH |
SOCAM_VSYNC_ACTIVE_HIGH | SOCAM_MASTER | SOCAM_DATAWIDTH_8 |
SOCAM_DATA_ACTIVE_HIGH,
};
It looks like I'll need to modify "soc_camera_platform" it in a way to at
least add a "fourcc" field that can be interpreted by the ceu driver for
the
"sh_mobile_ceu_set_bus_param" call to setup the hardware correctly.
No, subdevice drivers, using the mediabus API, know nothing about fourcc
codes, that belongs to the user side of the pixel format handling API. The
path, e.g., for the VIDIOC_S_FMT ioctl() is
soc_camera.c::soc_camera_s_fmt_vid_cap(V4L2_PIX_FMT_GREY)
sh_mobile_ceu_camera.c::sh_mobile_ceu_set_fmt(V4L2_PIX_FMT_GREY)
the latter will try to call the .s_mbus_fmt() method from
soc_camera_platform.c and will fail, because that got lost during the
v4l2-subdev conversion, which is a bug and has to be fixed, patch welcome.
But regardless of how I set this structure up, I don't see any direct
support
for a Grayscale mode data capture in the ceu driver. For example,
"sh_mobile_ceu_set_bus_param" does not contain V4L2_PIX_FMT_GREY in its
list
of fourcc formats. Yet based on the 7724 hardware manual, and from the
information I have received from Renesas, I'm not seeing any reason why
this
format should not be supported.
Is grayscale somehow supported under the current CEU driver?
Sure, that's what the pass-through mode with a standard soc-mbus format
conversion is for (see soc_mbus_get_fmtdesc()).
Any suggestions on how I might go about implementing support? I'm having
trouble seeing the dataflow through the driver at the moment...
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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