mipi csi2 can not receive data correctly! error on capturing video with ov9724 camera and imx6dl microcontroller

I am trying to interface omnivision's ov9724 camera with imx6dl microcontroller. The camera has only mipi interface with a single lane, and I am using only one lane for communication (one differential data lane and a differential clock lane).

iMx6dl pin          OV9724 pin
CSI0_MCLK(P4)  -    XCLK      -> Source clock: **24 MHz**
CSI_CLK0M(F4)  -    MCN    (MIPI_CLK_N)
CSI_CLK0P(F3)  -    MCP    (MIPI_CLK_P)
CSI_D0M(E4)    -    MDN0 (MIPI_D0_N)
CSI_D0P(E3)    -    MDP0 (MIPI_D0_P)

I ported the camera driver for ov5640 in "git://git.freescale.com/imx/linux-2.6-imx.git". Since the camera only has RAW-10 bit output, I edited the code based on a reference code I found online.

This is the relevant dts configuration I have edited.

ov9724_mipi: ov9724_mipi@10
{ 
compatible = "ovti,ov9724_mipi";
reg = <0x10>;
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_ipu1_3>;
clocks = <&clks IMX6QDL_CLK_CKO>; //&clks 201 ??
clock-names = "csi_mclk";
DOVDD-supply = <&sw4_reg>; /* 1.8v */
AVDD-supply = <&vgen5_reg>; /* 2.8v, on rev C board is VGEN3,
on rev B board is VGEN5 */
DVDD-supply = <&vgen1_reg>; /* 1.5v*/
pwn-gpios = <&gpio6 2 GPIO_ACTIVE_LOW>; /* active low: CSI0_DAT16 -   PWRDWN*/ //REF MANUAL PG : 1523
stby-gpios = <&gpio6 0 GPIO_ACTIVE_LOW>; /* active low: CSI0_DAT14 -      STANDBY - XSHUTDOWN*/
csi_id = <0>;
mclk = <24000000>;
mclk_source = <0>;
};

&mipi_csi {
status = "okay";
ipu_id = <0>;
csi_id = <0>;
v_channel = <0>; //v_channel 0: CSI0_IPU1; v_channel1: CSI1_IPU1; 2:     CSI0_IPU2; 3: CSI1_IPU2
lanes = <1>;
};

v4l2_cap_0 {
compatible = "fsl,imx6q-v4l2-capture";
ipu_id = <0>;
csi_id = <0>;
mclk_source = <0>;
status = "okay";
};


v4l2_out {
compatible = "fsl,mxc_v4l2_output";
status = "okay";
};

I am attaching the error log below. It looks like a clock issue to me, as referring to the errors, I find that these two bits are set according to the datasheet in Error register 1.

Bit 4: Error matching Frame Start with Frame End for Virtual Channel 0

Bit 28: Header ECC contains 2 errors. Unrecoverable.

I have configured the imx to use IPU - 1, CSI - 0, Virtual Channel - 0 and Number of lanes - 1. Please refer to the log below.

I think it might be something to do with the clock configuration but I am unsure how to go forward. I saw the dphy register settings mentioned in the "Debug Steps for customer MIPI Sensor" doc, which I think the author created based on the info available in document AN5305 (Page 14), which I am attaching here.

I configured the clock as follows.

In the camera sensor side according to the datasheet, Pixel clk = (ext_clk * pll_multiplier) / (sys_clk_div_pll * pre_pll_clk_div_pll * pix_clk_div_pll) = (24000000 * 0x3E) / (0x0A * 0x01 * 0x02) = 75.6 MHz.

Now for configuring the mipi dphy clock on the imx side, I used the following calculation. (For 1280 x 720 at 30 fps) (This calculation is based on the equations in AN5305 doc attached here, Section 3.4, Page 13).

Pixel clock = 1280 * 720 * 30 fps * 1 cycle/pixel * 1.35 blanking interval = 74.6 MHz

Total MIPI Data rate = 74.6 * 10 bits = 746 Mbps. For a 1 lane interface, MIPI clock = 746 / (Number of lanes ) / 2 = 746 / 1 / 2 = 373 MHz.

MIPI_CSI2_PHY_TST_CTRL1 setting = 373 MHz * 2 (DDR mode) = 746 MHz

Based on this value, i edited the mipi dphy settings as follows in mxc_mipi_csi2.c by referring to AN5305 page 14.

mipi_csi2_write(info, 0x00000001, MIPI_CSI2_PHY_TST_CTRL0);
mipi_csi2_write(info, 0x00000000, MIPI_CSI2_PHY_TST_CTRL1);
mipi_csi2_write(info, 0x00000000, MIPI_CSI2_PHY_TST_CTRL0);
mipi_csi2_write(info, 0x00000002, MIPI_CSI2_PHY_TST_CTRL0);
mipi_csi2_write(info, 0x00010044, MIPI_CSI2_PHY_TST_CTRL1);
mipi_csi2_write(info, 0x00000000, MIPI_CSI2_PHY_TST_CTRL0);
mipi_csi2_write(info, 0x00000012, MIPI_CSI2_PHY_TST_CTRL1); //750-800 MHz
mipi_csi2_write(info, 0x00000002, MIPI_CSI2_PHY_TST_CTRL0);
mipi_csi2_write(info, 0x00000000, MIPI_CSI2_PHY_TST_CTRL0);

I am still not sure the clock settings are correct. I am also unclear as to the clock settings for ov5640 mentioned in AN5305 Page 21. (I have attached it as an image here - MIPI CLK setting in AN5305.png). Why are they setting the PLL5 to 596 MHz?

Also, the ipu and mipi configs are as below.

mipi_csi: mipi_csi@021dc000 { /* MIPI-CSI */
compatible = "fsl,imx6q-mipi-csi2";
reg = <0x021dc000 0x4000>;
interrupts = <0 100 0x04>, <0 101 0x04>;
clocks = <&clks IMX6QDL_CLK_HSI_TX>,
<&clks IMX6QDL_CLK_EMI_SEL>,
<&clks IMX6QDL_CLK_VIDEO_27M>;
/* Note: clks 138 is hsi_tx, however, the dphy_c
* hsi_tx and pll_refclk use the same clk gate.
* In current clk driver, open/close clk gate do
* use hsi_tx for a temporary debug purpose.
*/
clock-names = "dphy_clk", "pixel_clk", "cfg_clk";
status = "disabled";
};



ipu1: ipu@02400000 {
#address-cells = <1>;
#size-cells = <0>;
compatible = "fsl,imx6q-ipu";
reg = <0x02400000 0x400000>;
interrupts = <0 6 IRQ_TYPE_LEVEL_HIGH>,
<0 5 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks IMX6QDL_CLK_IPU1>,
<&clks IMX6QDL_CLK_IPU1_DI0>, <&clks IMX6QDL_CLK_IPU1_DI1>,
<&clks IMX6QDL_CLK_IPU1_DI0_SEL>, <&clks IMX6QDL_CLK_IPU1_DI1_SEL>,
<&clks IMX6QDL_CLK_LDB_DI0>, <&clks IMX6QDL_CLK_LDB_DI1>;
clock-names = "bus",
"di0", "di1",
"di0_sel", "di1_sel",
"ldb_di0", "ldb_di1";
resets = <&src 2>;
bypass_reset = <0>;
};

I printed the "dphy_clk", "pixel_clk", and "cfg_clk" as shown below.

sh-4.3# dmesg | grep clk

[ 0.259781] imx-ipuv3 2400000.ipu: ipu_clk = 270000000
MIPI CSI2 cfg_clk: **27000000**
MIPI CSI2 dphy_clk: **198000000**
MIPI CSI2 pixel_clk: **396000000**
[ 0.381171] imx-ipuv3 2400000.ipu: pixel clk = 30919000
[ 0.381240] imx-ipuv3 2400000.ipu: try ipu internal clk
[ 0.381253] imx-ipuv3 2400000.ipu: rounded pix clk:30000000
[ 0.381258] imx-ipuv3 2400000.ipu: try ipu ext di clk
[ 0.381477] #### clk_pllv3_av_set_rate : rate 989407992, parent_rate 24000000, val 0x0, mfn 0x37035 mfd 0xf4240
[ 0.381509] imx-ipuv3 2400000.ipu: di clk:30919000
[ 0.381525] imx-ipuv3 2400000.ipu: round pixel clk:30919000
[ 0.428329] imx-ipuv3 2400000.ipu: pixel clk = 30919000
[ 0.428387] imx-ipuv3 2400000.ipu: try ipu internal clk
[ 0.428402] imx-ipuv3 2400000.ipu: rounded pix clk:30000000
[ 0.428408] imx-ipuv3 2400000.ipu: try ipu ext di clk
[ 0.428429] imx-ipuv3 2400000.ipu: di clk:30919000
[ 0.428442] imx-ipuv3 2400000.ipu: round pixel clk:**30919000**
OV9724 Clock csi_mclk: 24000000
[ 2.879715] galcore: clk_get vg clock failed, disable vg!

I saw that the pixel clk has been rounded to 30919000. I did not understand this part. Here the dphy_clk is 198 MHz. Do I have to change any extra pll settings or something?

KERNEL DEBUG LOG SHOWING MIPI ERROR

# ioctl_g_chip_ident #sensor chip is ov9724_mipi_camera
sensor supported frame size:
In mxc_v4l2_s_param
640x480
320x240
720x480
720x576
# ioctl_g_parm #
1280x720
1920x1080
2592x1944
176x144
1024x768
Current capabilities are 1001
sensor frame format: BG10
Current capturemode is 0 change to 0
sensor frame format: BG10
Current framerate is 30 change to 30
sensor frame format: BG10
sensor frame format:BG10
# ioctl_s_parm #
sensor frame format: BG10
sensor frame format: BG10
sensor frame format: BG10
sensor frame format: BG10
sensor frame format: BG10
# INIT MODE mode: 0 frame rate: 1 mode_original: 0 #
MIPI CSI2 Enable Status: 1
MIPI CSI2 Enable Status: 1
MIPI CSI2 Befor setting Lanes: info->lanes: 1
MIPI CSI2 Set Lanes: 0
MIPI CSI2 Set Datatype : 43 0x2b   --> RAW-10 datatype
Pixel Format is V4L2_PIX_FMT_SBGGR10

************ Changing to direct mode! Frame rate is : 1 Mode number is 0

Writing 0x24001b30 to register CSI_SENS_CONF Read Val: 0x4001b30
Writing 0x2cf04ff to register CSI_SENS_FRM_SIZE Read Val: 0x2cf04ff
Writing 0x2cf04ff to register CSI_ACT_FRM_SIZE Read Val: 0x2cf04ff
Writing 0xffffff2b to register IPU_CSI0_DI Read Val: 0xffffff2b
Writing 0x661 to register IPU_CONF Read Val: 0x661
Writing 0x2 to register CSI2IPU_SW_RST Read Val: 0x2

# OV9724 CHANGE MODE DIRECT # Frame Rate: 1 Mode : 4

@@@@@@@@@@@@@@@@@@@ STREAM OFF @@@@@@@@@@@@@@@@@@@@@@@
############## OV9724 REGISTER VALUES READBACK############## 
IPU_CONF = 0x661
IPU_CSI0_SENS_CONF_REG = 0x4001b30
IPU_CSI0_SENS_FRM_SIZE_REG = 0x2cf04ff
IPU_CSI0_ACT_FRM_SIZE_REG = 0x2cf04ff
IPU_CSI0_OUT_FRM_CTRL_REG = 0x0
IPU_CSI0_DI_REG = 0xffffff2b
IOMUXC_GPR1_REG = 0x48441005
CSI2IPU_SW_RST_REG = 0x2
@@@@@@@@@@@@@@@@@@@ STREAM ON @@@@@@@@@@@@@@@@@@@@@@@
Setting Virtual Channel to 0 Channel Reg Value: 2b
GEtting CSI Ready!!
############## OV9724 REGISTER VALUES ############## 
IPU_CONF = 0x661
IPU_CSI0_SENS_CONF_REG = 0x4001b30
IPU_CSI0_SENS_FRM_SIZE_REG = 0x2cf04ff
IPU_CSI0_ACT_FRM_SIZE_REG = 0x2cf04ff
IPU_CSI0_OUT_FRM_CTRL_REG = 0x0
IPU_CSI0_DI_REG = 0xffffff2b
IOMUXC_GPR1_REG = 0x48441005
CSI2IPU_SW_RST_REG = 0x2

MIPI CSI2 PHY_STATE : 0x300
MIPI_CSI2_VERSION : 0x3130302a
MIPI_CSI2_N_LANES : 0x0
MIPI_CSI2_PHY_SHUTDOWNZ : 0x1
MIPI_CSI2_DPHY_RSTZ : 0x1
MIPI_CSI2_DATA_IDS_1 : 0x0
MIPI_CSI2_DATA_IDS_2 : 0x0
MIPI_CSI2_PHY_TST_CTRL0 : 0x0
MIPI_CSI2_PHY_TST_CTRL1 : 0x2a2a

MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000000
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000000
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000000
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000010
MIPI CSI2 ERROR2 : 0x0
MIPI CSI2 ERROR1 : 0x10000000
MIPI CSI2 ERROR2 : 0x0
mipi csi2 can not receive data correctly!

I am unable to probe the clk and data lines as the DSO I have is only of 200 MHz. The waveforms I did observe I have attached below. (Yellow probe - DATA_P, Green probe - DATA_N, Blue - CLK_P, Pink - CLK_N). I am observing data on the data lines when turning on the streaming, but did not see anything on the clock line initially. Then when I decreased voltage division of clock lines to 100mV (data voltage is around 1 V), then I saw a waveform pattern in the clock, which looked like noise initially. Seems like clock is present when the data is present. But when I probe both the data lines, clock lines look like noise as shown in fig scope_15.bmp. I do not know why the clock is behaving as such - HARDWARE ISSUE? But in the imx side, a ddr clock is detected as per the MPHY MIPI CSI2 PHY_STATE register.

I know this is a long post, but I wanted to include everything I have done till date. I am a newbie to linux, and basically this is my first project. I will summarize my questions below.

1. What could be the reason for the MIPI CSI error seen in the log?
2. Does the clock in the waveforms look normal? Is it adequate for the mipi interface to work?
3. In case my dphy clock configuration is wrong, how to configure both imx and the camera clock? More importantly, how is the camera sensor clock related to the dphyclock?
4. In the document AN5605 page 21, what is the significance of the Clock 596MHz and what is the clock I should use?

Please let me know your thoughts.

Link to the AN5305 document- http://www.nxp.com/assets/documents/data/en/application-notes/AN5305.pdf

scope_2.bmp