Message-ID: <b2cf8a59-a8bc-405c-8b7e-78805d0b4502@oss.qualcomm.com>
Date: Mon, 5 Jan 2026 16:14:21 +0800
From: Wenmeng Liu <wenmeng.liu@....qualcomm.com>
To: Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: Dave Stevenson <dave.stevenson@...pberrypi.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 12/30/2025 7:33 PM, Sakari Ailus wrote:
> Hi Wenmeng,
> 
> On Tue, Dec 23, 2025 at 02:19:18PM +0800, Wenmeng Liu wrote:
>>
>>
>> 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 for investigating this.
> 
> Have you checked how long it actually takes elsewhere (where the sensor
> works) before the mode related registers are written (and when they start
> being written) on systems where it actually works? As I²C writes require
> sleeping and depend on a process getting scheduled a large number of times,
> this might play a role here.
> 
> These patches might be useful in sensor drivers at large (but won't address
> this problem)
> <URL:https://git.retiisi.eu/?p=~sailus/linux.git;a=shortlog;h=refs/heads/pm-resume-delay>.
> 

Hi Sakari,

Based on my testing, it takes about 6.5ms before the registers become 
writable. I believe this is not a CCI issue, because I have tested 
multiple platforms and only the Arducam 22-pin IMX577 shows this 
problem. This delay seems to correspond to the time required for T7. I 
made the following changes and ran multiple tests, and this approach 
works fine:

diff --git a/drivers/media/i2c/imx412.c b/drivers/media/i2c/imx412.c
index 459cca36493e..5be698863653 100644
--- a/drivers/media/i2c/imx412.c
+++ b/drivers/media/i2c/imx412.c
@@ -798,6 +798,9 @@ static int imx412_start_streaming(struct imx412 *imx412)
         const struct imx412_reg_list *reg_list;
         int ret;

+       /* Delay is required before streaming*/
+       usleep_range(7400, 8000);
+
         /* Write sensor mode registers */
         reg_list = &imx412->cur_mode->reg_list;
         ret = imx412_write_regs(imx412, reg_list->regs,
@@ -814,9 +817,6 @@ static int imx412_start_streaming(struct imx412 *imx412)
                 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);


 From the perspective of the spec timing, I believe the above 
modification to the delay position is an acceptable change. What do you 
think?

sensor link:
https://www.arducam.com/arducam-imx577-mini-camera-module-for-qualcomm-rb3g2.html
https://www.arducam.com/arducam-imx477-camera-module-for-depthai-oak-b0369.html

Thanks,
Wenmeng

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