media: imx219: Adjust PLL settings based on the number of MIPI lanes

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Commit ceddfd4493 ("media: i2c: imx219: Support four-lane operation")
added support for device tree to allow configuration of the sensor to
use 4 lanes with a link frequency of 363MHz, and amended the advertised
pixel rate to 280.8MPix/s.

However it didn't change any of the PLL settings, so actually it would
have been running overclocked in the MIPI block, and with the frame
rate and exposure calculations being wrong as the pixel rate was
unchanged.

The pixel rate and link frequency advertised were taken from the "Clock
Setting Example" section of the datasheet. However those are based on an
external clock of 12MHz, and are unachievable with a clock of 24MHz - it
seems PREPLLCLK_VT_DIV and PREPLLCK_OP_DIV can ONLY be set via the
automatic configuration documented in "9-1-2 EXCK_FREQ setting depend on
INCK frequency", not by writing the registers.
The closest we can get with a 24MHz clock is 281.6MPix/s and 364MHz.

Dropping all support for the 363MHz link frequency would cause problems
for existing users, so allow it, but log a warning that the requested
value is being changed to the supported one.

Fixes: ceddfd4493 ("media: i2c: imx219: Support four-lane operation")
Cc: stable@vger.kernel.org
Co-developed-by: Peyton Howe <peyton.howe@bellsouth.net>
Signed-off-by: Peyton Howe <peyton.howe@bellsouth.net>
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>

...

This commit is contained in:

Dave Stevenson 2025-01-23 15:37:49 +00:00 • committed by Hans Verkuil

parent da1e42d3fe

commit 591a07588c

1 changed files with 69 additions and 24 deletions

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drivers/media/i2c/imx219.c

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