Wandboard - I2C error when booting with HDMI cable

[Heiko Schocher]

Hello Fabio,

Hope you are fine?

Am 10.12.2019 um 01:33 schrieb Fabio Estevam:
> Hi Anatolij and Heiko,
> 
> When booting a wandboard with a HDMI cable connected I get the
> following I2C messages:
> 
> U-Boot 2020.01-rc4-00151-g8dc20b6ae3-dirty (Dec 09 2019 - 21:07:48 -0300)
> 
> CPU:   Freescale i.MX6QP rev1.0 at 792 MHz
> Reset cause: WDOG
> DRAM:  2 GiB
> force_idle_bus: sda=0 scl=1 sda.gp=0x6d scl.gp=0x6c
> force_idle_bus: failed to clear bus, sda=0 scl=1
> force_idle_bus: sda=0 scl=1 sda.gp=0x6d scl.gp=0x6c
> force_idle_bus: failed to clear bus, sda=0 scl=1

Hmm... seems to come from "arch/arm/mach-imx/i2c-mxv7.c" ...

> PMIC:  PFUZE100 ID=0x10
> MMC:   FSL_SDHC: 2, FSL_SDHC: 1, FSL_SDHC: 0
> Loading Environment from MMC... OK
> auto-detected panel HDMI
> Display: HDMI (1024x768)
> 
> The Wandboard logo is properly displayed via HDMI, but I am wondering
> what can we do to get rid of these I2C messages?
> 
> If the board is booted without the HDMI cable connected such messages
> do not appear.
> 
> Any ideas?

Hmm.. I have only a DL based wandboard ... but I try to find time
to boot it with a hdmi cable attached ... ok, bootline:

 > force_idle_bus: sda=0 scl=1 sda.gp=0x6d scl.gp=0x6c

-> sda pin is 0x6d = 109 = gpio4_13

in arch/arm/dts/imx6dl-pinfunc.h:
#define MX6QDL_PAD_KEY_ROW3__I2C2_SDA               0x264 0x64c 0x874 0x4 0x1
#define MX6QDL_PAD_KEY_ROW3__GPIO4_IO13             0x264 0x64c 0x000 0x5 0x0

Ok, so i2c bus 2. from imx6qdl-wandboard.dtsi:

  85 &i2c2 {
  86         clock-frequency = <100000>;
  87         pinctrl-names = "default";
  88         pinctrl-0 = <&pinctrl_i2c2>;
  89         status = "okay";
  90
  91         codec: sgtl5000 at a {

ok, there is this sgtl5000 chip ... audio codec ... I do not see how
this has something to do with hdmi cable ... a very fast look into
wiring diagrams, shows only, that i2c2 _sda/scl goes also to camera1
(FP124-334M4) connector (wb-edm-imx6-rev-c1.pdf C1 schematics). Should
have nothing to do with hdmi ...

May it is worth to check error codes in arch/arm/mach-imx/i2c-mxv7.c ?

  22         gpio_direction_input(p->sda.gp);
  23         gpio_direction_input(p->scl.gp);
  24
  25         imx_iomux_v3_setup_pad(p->sda.gpio_mode);
  26         imx_iomux_v3_setup_pad(p->scl.gpio_mode);
  27
  28         sda = gpio_get_value(p->sda.gp);
  29         scl = gpio_get_value(p->scl.gp);

especially the imx_iomux_v3_setup_pad calls are interesting ... is
gpio_mode set correctly ?

May the pinmux is not setup to gpio mode, and so deblocking does
not work and or wrong vaules

Oh, I see in board code:

450 int board_init(void)
451 {
452         /* address of boot parameters */
453         gd->bd->bi_boot_params = PHYS_SDRAM + 0x100;
454
455 #if defined(CONFIG_VIDEO_IPUV3)
456         setup_i2c(1, I2C1_SPEED_NON_DM, 0x7f, &mx6dl_i2c2_pad_info);
457         if (is_mx6dq() || is_mx6dqp()) {
458                 setup_i2c(1, I2C1_SPEED_NON_DM, 0x7f, &mx6q_i2c2_pad_info);
459                 setup_i2c(2, I2C2_SPEED_NON_DM, 0x7f, &mx6q_i2c3_pad_info);
460         } else {
461                 setup_i2c(1, I2C1_SPEED_NON_DM, 0x7f, &mx6dl_i2c2_pad_info);
462                 setup_i2c(2, I2C2_SPEED_NON_DM, 0x7f, &mx6dl_i2c3_pad_info);
463         }
464
465         setup_display();
466 #endif
467
468         return 0;
469 }

So forget my speculation above ... :-(

The only possibility is, that the hdmi cable blocks i2c bus 2 ...

Or timeout until it gets unblocked is too low!

May you increase timeout in "arch/arm/mach-imx/i2c-mxv7.c"

  49                 elapsed = get_timer(start_time);
  50                 if (elapsed > (CONFIG_SYS_HZ / 5)) {    /* .2 seconds */
  51                         ret = -EBUSY;

?

Currently no more ideas ... sorry.

bye,
Heiko
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