linux-kernel - Re: [PATCH] media: i2c: imx412: Extend the power-on waiting time

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Message-ID: <ffa7b849-51da-42f7-be1d-c3c7e1903e6e@oss.qualcomm.com>
Date: Mon, 22 Dec 2025 20:20:14 +0800
From: Wenmeng Liu <wenmeng.liu@....qualcomm.com>
To: Dave Stevenson <dave.stevenson@...pberrypi.com>
Cc: Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Wenmeng Liu <quic_wenmliu@...cinc.com>
Subject: Re: [PATCH] media: i2c: imx412: Extend the power-on waiting time



On 12/22/2025 8:11 PM, Dave Stevenson wrote:
> Hi Wenmeng & Sakari
> 
> On Mon, 22 Dec 2025 at 09:35, Wenmeng Liu <wenmeng.liu@....qualcomm.com> wrote:
>>
>>
>>
>>
>>>>
>>>> The Arducam IMX577 module requires a longer reset time than the 1000µs
>>>> configured in the current driver. Increase the wait time after power-on
>>>> to ensure proper initialization.
>>>
>>> Is this somehow specific to the Arducam module? If so, what's there in the
>>> module that requires this?
>>>
>>
>>
>> Yes, This issue occurred on the Arducam 22-pin IMX577 module.
>> I have tried changing the sequence of regulator, reset, and clock, and
>> found that this module must wait a sufficient amount of time after reset
>> before registers can be written (10 ms is a safe duration). This issue
>> did not occur when using other IMX577 modules.
> 
> Is it the probe that fails, or starting streaming?
> 
> Google has found me a datasheet for IMX577 at [1]. I'm hoping you have
> an official datasheet, so do correct the following if that has any
> updates.
> Section 7-2-2 on page 30 for the startup sequence.
> 
> The sequence is meant to be regulators, INCK, and then XCLR. The
> driver does XCLR before clock, so that would appear to be wrong.
> 
> It also states that T6 as the time from XCLR to being able to read the
> version register is min 0.6ms, but T7 as the time before you can send
> "Streaming Commmand" is min 8ms "To complete reading all parameters
> from NVM".
> That would be a difference between probe and start_streaming, although
> admittedly sending the mode and control setup I2C commands will take
> up some of that time.
> 
> Plausibly the other set of modules don't have the NVM programmed and
> hence they are ready sooner. Either way I'd say that does mean the
> driver currently isn't following the defined power up sequence, and
> the patch looks reasonable for IMX577.
> However as this is a shared driver does IMX412 have this restriction
> too? I can't find a datasheet for that one to check. For the sake of
> ~9ms it's not going to make a huge difference though.
> 
>    Dave
> 
> [1] https://en.sunnywale.com/uploadfile/2021/1222/IMX577-AACK-C(Awin).pdf
> 

Hi Dave,

this issue appears in the write register when streamon 
imx412_write_regs.  poweron->streamon.

static int imx412_start_streaming(struct imx412 *imx412)
{
         const struct imx412_reg_list *reg_list;
         int ret;

         /* Write sensor mode registers */
         reg_list = &imx412->cur_mode->reg_list;
         ret = imx412_write_regs(imx412, reg_list->regs,
                                 reg_list->num_of_regs);
         if (ret) {
                 dev_err(imx412->dev, "fail to write initial registers\n");
                 return ret;
         }

         /* Setup handler will write actual exposure and gain */
         ret =  __v4l2_ctrl_handler_setup(imx412->sd.ctrl_handler);
         if (ret) {
                 dev_err(imx412->dev, "fail to setup handler\n");
                 return ret;
         }

         /* Delay is required before streaming*/
         usleep_range(7400, 8000);

         /* Start streaming */
         ret = imx412_write_reg(imx412, IMX412_REG_MODE_SELECT,
                                1, IMX412_MODE_STREAMING);
         if (ret) {
                 dev_err(imx412->dev, "fail to start streaming\n");
                 return ret;
         }

         return 0;
}
 > but T7 as the time before you can send "Streaming Commmand" is min 8ms "
I think the usleep_range(7400, 8000) represents the 8ms duration 
required by T7.

Thanks,
Wenmeng