Message-ID: <88bcd810-872e-4705-91c0-df2a35f4a3b9@oss.qualcomm.com>
Date: Tue, 23 Dec 2025 14:19:18 +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 10:16 PM, Dave Stevenson wrote:
> Hi Wenmeng
> 
> On Mon, 22 Dec 2025 at 12:20, Wenmeng Liu <wenmeng.liu@....qualcomm.com> wrote:
>>
>>
>>
>> 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.
> 
> I'd missed that one.
> If you've delayed for 10-12ms between coming out of reset and sending
> the first command, then does the Arducam module still require another
> 8ms here, or can that be removed as you've already complied with T7?
> 
> Have you asked Arducam as to why their module takes longer? I can't
> find an IMX577 module listed on their product pages so presumably it's
> discontinued. There are a few links for a Luxonis Oak DepthAI board
> [1] which is made by Arducam and is using IMX577, so is it that one?
> Generally I've not encountered an issue with Arducam adding any weird
> delay circuits on their sensor boards.
> 
>    Dave
> 
> [1] https://shop.luxonis.com/products/oak-ffc-imx577-m12
> 
>> Thanks,
>> Wenmeng
>>
>>

Hi Dave,

Based on my testing, moving usleep_range(7400, 8000); to the beginning 
of the imx412_start_streaming function allows the Arducam IMX577 module 
to work properly. In contrast, other IMX577 sensors do not require this 
delay. I believe this corresponds to the T7 timing requirement. I have 
not yet confirmed this with Arducam, and I plan to compare once I 
receive another type Arducam IMX577 sensor.

Thanks,
Wenmeng

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