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linuxlinux-kernelvideo-capturev4l2

What causes "resource temporarily unavailable" in v4l2

I have compiled adv7180 driver available here.

I am unloading the ov5642 cameradriver(which in my case is built-in) and loading the adv7180_tvin module and after I am loading mxcv4l2_capture module which creates video0 in /dev/. (dmesg command says: "mxc camera on IPU2_CSI1 registered as video0")

But when I try to access video0 with v4l2-ctl I got a message "resource temporarily unavailable" or when I am using gstreamer I got message "Can not open /dev/video0" (but the device is really created).

Is that a problem in device tree settings or it can be caused by something else? Which tools should I use to find out what causes this issue?

My device tree settings look like below:

&i2c3{
adv7180: adv7180@20{
compatible = "adv,adv7180";
reg = <0x20>;
clocks = <&clks IMX6QDL_CLK_CKO2>;
clock-names = "csi_mclk";
pwn-gpios = <&gpio3 10 GPIO_ACTIVE_LOW>;
ipu_id = <1>;
csi_id = <1>;
mclk = <24000000>;
mclk_source = <0>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_hummingboard2_parallel>;

cvbs = <1>;

};
};

I need to add that before adv7180 I was using above settings for ov5642 camera (excluding cvbs setting) and everything worked properly.

EDIT:

Ok I got one clue.

When I load modules in dmesg message "mxc_v4l2_master_attach: ipu(0:1)/csi(1:1)/mipi(0:0) doesn't match" shows. But it only happens when ipu_id=<1> in v4l2_cap device tree settings and in adv7180 settings. When i change ipu_id to ipu_id=<0> in v4l2 settings and adv7180 dmesg now shows "parallel attach to IPU1 CSI1 and I can access the /dev/video0 succesfully with v4l2-ctl tool.

But In my case there is only one possibility to use IPU2_CSI1.

Why can't I set IPU2 to adv7180 when I was using it successfully to ov5642 ?

Solution

  • As per my knowledge i.MX6 having two IPUs. I think by default IPU1 parallel interface is not enabled in the board file. So you need to check the IOMUXC_GPR1 register setting (bit 19 and 20) for IPU/CSI1 and pass the csi_id in your camera driver. IPU to CSI Connectivity

    As you are using the parallel interface so check your pin muxing setting as well in your device tree. (which is not required for serial interface.)

    Edit: There are two ways which you can follow to update the register setting from the kernel space (boardfile or camera driver) itself:

    1. From the board file:

    struct regmap *gpr
gpr = syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
regmap_update_bits(gpr, IOMUXC_GPR1, 1 << 20, 1 << 20);

    2. From the boardfile or camera driver

    void __iomem *va_ipu2_address;
u32 reg_val;
va_ipu2_address = ioremap(0x20e0004,0xe0004);
reg_val = readl(va_ipu2_address);
/* Enable parallel interface to IPU2 CSI1.  */
writel(reg_val | 1 << 20, va_ipu2_address);