[PATCH AUTOSEL 6.17-6.6] media: ov08x40: Fix the horizontal flip control

[Sasha Levin <sashal@kernel.org>]

From: Hao Yao <hao.yao@intel.com>

[ Upstream commit c7df6f339af94689fdc433887f9fbb480bf8a4ed ]

The datasheet of ov08x40 doesn't match the hardware behavior.
0x3821[2] == 1 is the original state and 0 the horizontal flip enabled.

Signed-off-by: Hao Yao <hao.yao@intel.com>
Reviewed-by: Hans de Goede <hansg@kernel.org>
Tested-by: Hans de Goede <hansg@kernel.org> # ThinkPad X1 Carbon Gen 12 & Gen 13
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

LLM Generated explanations, may be completely bogus:

YES

- What it fixes: The horizontal flip (HFLIP) control polarity was wrong
  for the OV08X40 sensor. Hardware enables H-mirror when bit 2 of
  register 0x3821 is cleared, but the driver treated setting the bit as
  “flip on”. The fix inverts this polarity so V4L2_CID_HFLIP now matches
  actual hardware behavior.
- Precise change: In `ov08x40_set_ctrl_hflip()`, the write toggling
  `OV08X40_REG_MIRROR` bit 2 is flipped:
  - Before: `ctrl_val ? val | BIT(2) : val & ~BIT(2)`
  - After: `ctrl_val ? val & ~BIT(2) : val | BIT(2)`
  - Location: drivers/media/i2c/ov08x40.c:1651
- Scope and containment:
  - Only one line in a single driver file is changed:
    `drivers/media/i2c/ov08x40.c`.
  - The function reads the current register value first and only changes
    bit 2, preserving other bits (drivers/media/i2c/ov08x40.c:1646,
    1651).
  - Vertical flip handling remains unchanged and continues to set bit 2
    of 0x3820 when enabled (drivers/media/i2c/ov08x40.c:1666), showing
    the change is isolated to HFLIP.
  - The HFLIP control is wired through the standard control path
    (`ov08x40_set_ctrl()` case V4L2_CID_HFLIP →
    `ov08x40_set_ctrl_hflip()`, drivers/media/i2c/ov08x40.c:1735) and
    HFLIP is created as a standard V4L2 control
    (drivers/media/i2c/ov08x40.c:2153).
- User impact: Without this fix, user-space sees inverted behavior for
  HFLIP (enabling the control does not produce the expected mirror),
  which is a clear functional bug affecting image orientation and any
  applications relying on correct orientation metadata/control.
- Risk assessment:
  - Minimal risk: a single-bit polarity correction in a register write,
    no ABI/API change, no architectural changes, and constrained to the
    ov08x40 driver.
  - Safe behavior: other bits are preserved; change is applied only when
    the device is powered/streaming via existing PM checks.
  - Real-world validation: Reviewed and Tested-by are present, including
    testing on ThinkPad X1 Carbon Gen 12/13, which reduces regression
    risk.

This is a small, targeted, and user-visible bugfix that aligns with
stable backporting rules and should be backported.

 drivers/media/i2c/ov08x40.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ov08x40.c b/drivers/media/i2c/ov08x40.c
index e0094305ca2ab..90887fc54fb0e 100644
--- a/drivers/media/i2c/ov08x40.c
+++ b/drivers/media/i2c/ov08x40.c
@@ -1648,7 +1648,7 @@ static int ov08x40_set_ctrl_hflip(struct ov08x40 *ov08x, u32 ctrl_val)
 
 	return ov08x40_write_reg(ov08x, OV08X40_REG_MIRROR,
 				 OV08X40_REG_VALUE_08BIT,
-				 ctrl_val ? val | BIT(2) : val & ~BIT(2));
+				 ctrl_val ? val & ~BIT(2) : val | BIT(2));
 }
 
 static int ov08x40_set_ctrl_vflip(struct ov08x40 *ov08x, u32 ctrl_val)
-- 
2.51.0