Re: [PATCH v5] can: dev: can_fill_info(): don't wake up controller if interface is down

On 20.10.2026 15:53:40, ChunYuZhiQiang wrote:

If the interface is down, the CAN controller might be powered down, the
clock disabled, and/or its external reset asserted.

Don't call do_get_berr_counter() or do_get_auto_tdcv() to read the CAN
controller if the interface is down. This fixes a generic logic problem
that exists on all platforms.

As a result, IFLA_CAN_BERR_COUNTER and IFLA_CAN_TDC are no longer
reported for down interfaces. This is intentional: the counters are not
meaningful in that state, and calling into the driver can wake a
runtime-suspended controller or touch registers whose clocks are gated.

Fixes: ec56acfef2af1 ("can: flexcan: flexcan_get_berr_counter(): switch on clocks before accessing ecr register")
Cc: <redacted>
Signed-off-by: ChunYuZhiQiang <redacted>
---
v5:
 - Gate can_tdc_fill_info() on netif_running() for IFLA_CAN_TDC, as
   requested by Marc Kleine-Budde. This branch has no IFLA_CAN_XL_TDC
   definition or call path at all.
 - Keep the TDC part of can_get_size() consistent with can_fill_info(),
   without hiding the non-TDC data bittiming attributes.
 - Document that IFLA_CAN_BERR_COUNTER is no longer reported for down
   interfaces, and explain why this is acceptable for stable.
 - Clarify the Fixes: rationale.

Thanks for the patch. In the future, please don't send vN+1 as a reply
to vN.

regards,
Marc

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