On Mon, May 18, 2020 at 09:13:54PM +0300, Grygorii Strashko wrote:
Hi Greg,
On 18/05/2020 20:35, Greg Kroah-Hartman wrote:
From: Clay McClure <c...@daemons.net>
[ Upstream commit b6d49cab44b567b3e0a5544b3d61e516a7355fad ]
Commit d1cbfd771ce8 ("ptp_clock: Allow for it to be optional") changed
all PTP-capable Ethernet drivers from `select PTP_1588_CLOCK` to `imply
PTP_1588_CLOCK`, "in order to break the hard dependency between the PTP
clock subsystem and ethernet drivers capable of being clock providers."
As a result it is possible to build PTP-capable Ethernet drivers without
the PTP subsystem by deselecting PTP_1588_CLOCK. Drivers are required to
handle the missing dependency gracefully.
Some PTP-capable Ethernet drivers (e.g., TI_CPSW) factor their PTP code
out into separate drivers (e.g., TI_CPTS_MOD). The above commit also
changed these PTP-specific drivers to `imply PTP_1588_CLOCK`, making it
possible to build them without the PTP subsystem. But as Grygorii
Strashko noted in [1]:
On Wed, Apr 22, 2020 at 02:16:11PM +0300, Grygorii Strashko wrote:
Another question is that CPTS completely nonfunctional in this case and
it was never expected that somebody will even try to use/run such
configuration (except for random build purposes).
In my view, enabling a PTP-specific driver without the PTP subsystem is
a configuration error made possible by the above commit. Kconfig should
not allow users to create a configuration with missing dependencies that
results in "completely nonfunctional" drivers.
I audited all network drivers that call ptp_clock_register() but merely
`imply PTP_1588_CLOCK` and found five PTP-specific drivers that are
likely nonfunctional without PTP_1588_CLOCK:
NET_DSA_MV88E6XXX_PTP
NET_DSA_SJA1105_PTP
MACB_USE_HWSTAMP
CAVIUM_PTP
TI_CPTS_MOD
Note how these symbols all reference PTP or timestamping in their name;
this is a clue that they depend on PTP_1588_CLOCK.
Change them from `imply PTP_1588_CLOCK` [2] to `depends on PTP_1588_CLOCK`.
I'm not using `select PTP_1588_CLOCK` here because PTP_1588_CLOCK has
its own dependencies, which `select` would not transitively apply.
Additionally, remove the `select NET_PTP_CLASSIFY` from CPTS_TI_MOD;
PTP_1588_CLOCK already selects that.
[1]: https://lore.kernel.org/lkml/c04458ed-29ee-1797-3a11-7f3f56055...@ti.com/
[2]: NET_DSA_SJA1105_PTP had never declared any type of dependency on
PTP_1588_CLOCK (`imply` or otherwise); adding a `depends on PTP_1588_CLOCK`
here seems appropriate.
Cc: Arnd Bergmann <a...@arndb.de>
Cc: Richard Cochran <richardcoch...@gmail.com>
Cc: Nicolas Pitre <n...@fluxnic.net>
Cc: Grygorii Strashko <grygorii.stras...@ti.com>
Cc: Geert Uytterhoeven <ge...@linux-m68k.org>
Fixes: d1cbfd771ce8 ("ptp_clock: Allow for it to be optional")
Signed-off-by: Clay McClure <c...@daemons.net>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
Could you drop this patch, pls?
it's not for stable and can cause build failures.
My bad - now dropped. Sorry!
--
Thanks,
Sasha
