| Subject | Re: [PATCH 5.6 019/194] net: Make PTP-specific drivers depend on PTP_1588_CLOCK | From | Grygorii Strashko <> | Date | Mon, 18 May 2020 21:13:54 +0300 |
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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_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-1797-3a11-7f3f560553e6@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 <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.
-- Best regards, grygorii
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