linux-kernel - Re: [PATCH v2] media: i2c: imx412: wait for NVM read (T7) before programming mode registers

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Message-ID: <6126ae90-6f46-46f4-9a28-1b8d7ef69277@kernel.org>
Date: Mon, 12 Jan 2026 11:59:38 +0000
From: Bryan O'Donoghue <bod@...nel.org>
To: Wenmeng Liu <wenmeng.liu@....qualcomm.com>,
 Sakari Ailus <sakari.ailus@...ux.intel.com>
Cc: mchehab@...nel.org, linux-media@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] media: i2c: imx412: wait for NVM read (T7) before
 programming mode registers

On 12/01/2026 11:50, Wenmeng Liu wrote:
> -- if disable gpiod_set_value_cansleep(imx412->reset_gpio, 1); form
> imx412_power_off, the issue will not happen.

Yeah this is basically what I said in the last email.

The state transition diagram for starting the part will assume reset is 
asserted.

So in power_on() - you need to assert reset prior to powering on and 
clocking the part - which is the eqivalent logic to what you posted above.

The reason you should do this in power_on() is it doesn't assume 
power_off has run first.

power_on should establish the initial conditions required to power on 
the device, in this case, we've established you need to have reset 
asserted first.

---
bod