AnsweredAssumed Answered

i.MX6Q LVDS Timing issue

Question asked by sanjeev sharma on Aug 18, 2015
Latest reply on Aug 27, 2015 by sanjeev sharma

Hi all,

 

I have a custom iMX6q derived from nitrogen6x Board and I wanted to use a LVDS display 1280*800 with clock frequency minimum 60 and Maximum 80 MHZ.

The display has been configured for the 71 MHZ and below is the content of dts i have been using for the custom board.

 

Kernel is built using boundary-imx_3.14.28_1.0.0_ga branch from here https://github.com/boundarydevices/linux-imx6/commits/boundary-imx_3.14.28_1.0.0_ga and ldb driver successfully loaded. I could see that fb0 and fb1 device is created in /dev/directory.

 

To verify the Frame-buffer functionality I have used fb-test app which successfully fill frame-buffer with color to the screen.Attached FullSizeRender1.jpg is the one which shows that green color has been filled in framebuffer but When I tried to send random data to /dev/fb0 (dd if=/dev/urandom of=/dev/fb0) I could see horizontal lines FullSizeRender.jpg which is not the expected output.

 

Header 1

fb_lvds: fb@1 {

        compatible = "fsl,mxc_sdc_fb";

        disp_dev = "ldb";

        interface_pix_fmt = "RGB24";

        default_bpp = <24>;

        int_clk = <0>;

        late_init = <0>;

        status = "disabled";

    };

 

 

&ldb {

    status = "okay";

 

    lvds_channel0: lvds-channel@0 {

        crtc = "ipu1-di1";

        fsl,data-mapping = "spwg";

        fsl,data-width = <24>;

        status = "okay";

        primary;

 

        display-timings {

kyoceratcg121wxlpx: kyoceratcg121wxlpx {

                clock-frequency = <71000000>;

                hactive = <1280>;

                vactive = <800>;

                hback-porch = <48>;

                hfront-porch = <80>;

                vback-porch = <15>;

                vfront-porch = <2>;

                hsync-len = <32>;

                vsync-len = <6>;

}

 

In addition to that,I could see some strange kernel message appearing while booting in the area around ldb clk parent which can't be ignored while investigating the problem.

 

imx-ipuv3 2400000.ipu: IPU DMFC NORMAL mode: 1(0~1), 5B(4,5), 5F(6,7)

imx-ipuv3 2800000.ipu: IPU DMFC NORMAL mode: 1(0~1), 5B(4,5), 5F(6,7)

imx-ipuv3 2400000.ipu: use special clk parent

imx-ipuv3 2400000.ipu: disp=1, pixel_clk=71103000 71458646 parent=71458646 div=1

imx-ipuv3 2400000.ipu: IPU DMFC DP HIGH RESOLUTION: 1(0,1), 5B(2~5), 5F(6,7)

imx-ipuv3 2400000.ipu: IPU Warning - IPU_INT_STAT_10 = 0x00100000

imx-ipuv3 2400000.ipu: IPU Warning - IPU_INT_STAT_10 = 0x00100000

imx-ipuv3 2400000.ipu: use special clk parent

imx-ipuv3 2400000.ipu: disp=1, pixel_clk=71103000 71458646 parent=71458646 div=1

 

I would really appreciate if someone look into this issue and help me out what could be the potential reason for this cause.

 

Regards

Sanju

Attachments

Outcomes