[PATCH v3 0/3] media: i2c: ov02c10: Fix brownouts and power sequence

[Saikiran <bjsaikiran@gmail.com>]

This series addresses stability issues with the OV02C10 sensor on Qualcomm
Snapdragon X Elite (X1E80100) platforms, specifically the Lenovo Yoga Slim 7x.

Note: This series supersedes all previous patch sets submitted by me regarding
OV02C10 / media stability and cleanup on X1E80100 (including the 'pipeline
lock' and 'brownout' series). Please disregard prior versions.

Problem 1: Brownouts during rapid cycling
On this platform, the RPMh-controlled regulators lack active discharge, taking
~2.3s to passively discharge. Rapid close/open cycles (e.g., WebRTC checks)
re-enable regulators while the rails are floating, causing the sensor to hang.
Previous attempts to manage this via open-loop delays in power_on were deemed
incorrect.

Problem 2: Incorrect Power Sequence
The driver was not strictly following the datasheet power-up timing (T1/T2),
potentially leading to race conditions between the reset pin and power rails.

Problem 3: Race condition on removal
The remove() function freed resources before powering off the device, causing
use-after-free errors if userspace (PipeWire) accessed controls during removal.

Solution in v3:
1. Implement Runtime PM Autosuspend (1000ms). This prevents the driver from
   cutting power during rapid user interactions, sidestepping the slow
   regulator discharge window entirely. (Patch 3)
2. Enforce strict datasheet power-on sequencing with ample delays to satisfy
   maintainer requirements for clean boot. (Patch 2)
3. Fix the remove() race condition by reordering cleanup. (Patch 1)

Changes in v3:
- Dropped the "always-on" regulator patch from v2.
- Added Runtime PM Autosuspend support (Patch 3).
- Added strict power-on sequencing with 10ms/20ms delays (Patch 2).
- Added fix for use-after-free in remove() (Patch 1).

Link: https://lore.kernel.org/linux-media/20260125171745.484806-1-bjsaikiran@gmail.com/T/#t [1]

Saikiran (3):
  media: i2c: ov02c10: Fix use-after-free in remove function
  media: i2c: ov02c10: Correct power-on sequence and timing
  media: i2c: ov02c10: Use runtime PM autosuspend to avoid brownouts

 drivers/media/i2c/ov02c10.c | 70 ++++++++++++++++++++++++++++++-------
 1 file changed, 58 insertions(+), 12 deletions(-)