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 clay@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_MODNote 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.
[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 arnd@arndb.de Cc: Richard Cochran richardcochran@gmail.com Cc: Nicolas Pitre nico@fluxnic.net Cc: Grygorii Strashko grygorii.strashko@ti.com Cc: Geert Uytterhoeven geert@linux-m68k.org Fixes: d1cbfd771ce8 ("ptp_clock: Allow for it to be optional") Signed-off-by: Clay McClure clay@daemons.net Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org
Could you drop this patch, pls? it's not for stable and can cause build failures.
My bad - now dropped. Sorry!