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ptp_clock: future-proofing drivers against PTP subsystem becoming optional

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Drivers must be ready to accept NULL from ptp_clock_register() if the
PTP clock subsystem is configured out.

This patch documents that and ensures that all drivers cope well
with a NULL return.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Eugenia Emantayev <eugenia@mellanox.com>
Acked-by: Richard Cochran <richardcochran@gmail.com>
Acked-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nicolas Pitre 2016-09-20 19:25:58 -04:00 • committed by David S. Miller
parent d270f76c2d
commit efee95f42b
9 changed files with 19 additions and 14 deletions
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5
include/linux/ptp_clock_kernel.h
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@ -127,6 +127,11 @@ struct ptp_clock;
*
* @info: Structure describing the new clock.
* @parent: Pointer to the parent device of the new clock.
*
* Returns a valid pointer on success or PTR_ERR on failure. If PHC
* support is missing at the configuration level, this function
* returns NULL, and drivers are expected to gracefully handle that
* case separately.
*/
extern struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,