MCLK configuration of Qualcomm platform camera

Preface
MCLK It's the main control chip Provide to cam sensor The frequency of normal operation ,

Qcom The platform is generally not 24MHz, From other clock sources , Measured at 23.8MHz about .

When turning on the camera , To measure this clock .

cam snesor You can use the clock provided by the platform or the built-in clock source , But the software configuration should be consistent .

Platform clock source frequency can be modified , If not, you can add a new group .

Hardware platform ：msm8909、msm8953

software platform ：Android8.1、Android9.0

Reference documents ：

KBA_170619001341_3__Camera_How_to_change_MCLK_driv.pdf

Catalog

Preface

debugging see cam mclk

debugging see mclk frequency

debugging modify mclk frequency

debugging modify mclk Driving ability

debugging open mclk Related drivers log

debugging see cam mclk

  TIMER_CLK Refers to the... Connected by the camera sensor PHY The operating frequency of the interface .

for example ,PHY0 CAMSS_PHY0_CSI0PHYTIMER_CLK.

route ：

kernel/arch/arm/boot/dts/msm/msmXXXX-camera.dtsi

You can set... In the above file , among XXX Means in use MSM Chipset .

in addition , It can also be confirmed during camera data streaming , The way is through adb shell Check the corresponding clock information .

The following commands can be issued through the command prompt window to confirm PHY0 Timer clock value : /* msm8909 Android5.0/8.0 */

Instructions ：

  adb root
  adb remount
  adb shell
  cd /sys/kernel/debug/clk/gcc_camss_csi0phytimer_clk
  cd /sys/kernel/debug/clk/gcc_camss_mclk0_clk/
  cat measure
  200000146 
  24000292 
debugging see mclk frequency
camera When it's running , This value right here is mclk Output clock frequency ( Default 23800000)

adb shell cat sys/kernel/debug/clk/gcc_camss_mclk0_clk/measure
Add ：

msm8909 Default 24M The specific configuration is kernel/drivers/clk/qcom/clock-gcc-8909.c
The modification method is as follows , example It is amended as follows 27MHz
View the current mclk Information about

adb shell
/sys/kernel/debug/clk/gcc_camss_mclk0_clk
echo 1 > enable  // Give Way mclk Direct output camera A clock of normal operating frequency
cat measure     // stay camera When it's working properly You can view the current clock frequency
cat list_rates     // View the current mclk List of supported frequencies
debugging modify mclk frequency
camera Change the default mclk Clock configuration // msm8909

Code such as ：

Kernel Modify clock source

  kernel/drivers/clk/qcom/clock-gcc-8909.c
  @@ -837,6 +837,12 @@ static struct rcg_clk camss_gp1_clk_src = {
   static struct clk_freq_tbl ftbl_gcc_camss_mclk0_1_clk[] = {
    F( 24000000,    gpll2,  1,  1,  33),
  + F( 27000000,    gpll0,  1, 2, 59),
  +/* Begin: add by sys for set camera0 mclk 27MHz */
  + // set cma0_mclk 27MHz add by sys
  + // F(f, s, div, m, n)
  + // target clock=(source clock/div)*(M/N), 27=(800/1)*(2/59)
  +/* End:   add by sys for set camera0 mclk 27MHz */
    F( 66670000,    gpll0,  12, 0,  0),
    F_END
   };
vendor modify lib In drive mclk To configure

  /vendor/qcom/proprietary/mm-camera/mm-camera2/
media-controller/modules/sensors/sensor_libs/ov8865_hct/ov8865_hct_lib.c
  @@ -143,7 +143,7 @@ static struct msm_sensor_power_setting power_setting[] = {
     {
       .seq_type = SENSOR_CLK,
       .seq_val = SENSOR_CAM_MCLK,
  -    .config_val = 24000000,
  +    .config_val = 27000000, //24000000,
       .delay = 10,
     },
debugging modify mclk Driving ability
        /*sensors */
        cam_sensor_mclk0_default: cam_sensor_mclk0_default {
            /* MCLK0 */
            mux {
                /* CLK, DATA */
                pins = "gpio26";
                function = "cam_mclk";
            };
            config {
                pins = "gpio26";
                bias-disable; /* No PULL */
                //* 2 mA */ /* change to 4mA, 2, 4, 6, 8, 10… max is 16mA*/
                // Default 2ma, The maximum value can be changed to 16ma
                drive-strength = <2>; /* 2 MA */
            };
        };
debugging open mclk Related drivers log
route ：

kernel\msm-4.9\drivers\media\platform\msm\camera_v2\common\cam_soc_api.c

Code such as ：

-#define CDBG(fmt, args...) pr_debug(fmt, ##args)
+#define CDBG(fmt, args...) pr_err(fmt, ##args)