Re: [PATCH 1/2] dt-bindings: reset: imx8mq: Add _N suffix to IMX8MQ_RESET_MIPI_CSI*_RESET

Philipp Zabel
2026-03-31T12:45:21Z

On Di, 2026-03-31 at 18:13 +0800, Robby Cai wrote:
> The assert logic of the MIPI CSI reset signals is active-low on i.MX8MQ,
> but the existing names do not indicate this explicitly. To improve
> consistency and clarity, append the _N suffix to all
> IMX8MQ_RESET_MIPI_CSI*_RESET definitions. The deprecated
> IMX8MQ_RESET_MIPI_CSI*_RESET versions remain temporarily for DT ABI
> compatibility and will be removed at an appropriate time in the future.

The register description in the latest reference manual I can download,
IMX8MDQLQRM Rev. 3.1 (06/2021), still call these bits
MIPI_CSI1_CORE_RESET and so on (without _N). There is no mention of
polarity in the bitfield description. Is a documentation update
planned?

Right now I'd say this improves clarity, but reduces consistency with
existing documentation.

Are these bits self-clearing, or can the reset be asserted by writing
0? As it stands, the CSI driver using these resets, imx8mq-mipi-csi2.c,
only calls reset_control_assert() in imx8mq_mipi_csi_sw_reset():

/*
* these are most likely self-clearing reset bits. to make it
* more clear, the reset-imx7 driver should implement the
* .reset() operation.
*/
ret = reset_control_assert(state->rst);

This will probably have to be turned into a deassert together with the
reset driver change.

regards
Philipp