Hi Clay, Thanks for your patch!
On Tue, Apr 28, 2020 at 11:14 AM Clay McClure <[email protected]> wrote: > 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() and found > six that look like 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 > PTP_1588_CLOCK_IXP46X > > Note how they all reference PTP or timestamping in their name; this is a > clue that they depend on PTP_1588_CLOCK. > > Change these drivers back [2] to `select PTP_1588_CLOCK`. Note that this > requires also selecting POSIX_TIMERS, a transitive dependency of > PTP_1588_CLOCK. If these drivers have a hard dependency on PTP_1588_CLOCK, IMHO they should depend on PTP_1588_CLOCK, not select PTP_1588_CLOCK. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected] In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
