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net: Make PTP-specific drivers depend on PTP_1588_CLOCK 

Commit d1cbfd771c ("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: d1cbfd771c ("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>
This commit is contained in:
Clay McClure 2020-04-29 00:59:00 -07:00 committed by David S. Miller
parent 610a9346c1
commit b6d49cab44
5 changed files with 5 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/net/dsa/mv88e6xxx/Kconfig
View File

@ -24,8 +24,8 @@ config NET_DSA_MV88E6XXX_PTP
bool "PTP support for Marvell 88E6xxx"
default n
depends on NET_DSA_MV88E6XXX_GLOBAL2
depends on PTP_1588_CLOCK
imply NETWORK_PHY_TIMESTAMPING
imply PTP_1588_CLOCK
help
Say Y to enable PTP hardware timestamping on Marvell 88E6xxx switch
chips that support it.

1
drivers/net/dsa/sja1105/Kconfig
View File

@ -20,6 +20,7 @@ tristate "NXP SJA1105 Ethernet switch family support"
config NET_DSA_SJA1105_PTP
bool "Support for the PTP clock on the NXP SJA1105 Ethernet switch"
depends on NET_DSA_SJA1105
depends on PTP_1588_CLOCK
help
This enables support for timestamping and PTP clock manipulations in
the SJA1105 DSA driver.

2
drivers/net/ethernet/cadence/Kconfig
View File

@ -35,8 +35,8 @@ config MACB
config MACB_USE_HWSTAMP
bool "Use IEEE 1588 hwstamp"
depends on MACB
depends on PTP_1588_CLOCK
default y
imply PTP_1588_CLOCK
---help---
Enable IEEE 1588 Precision Time Protocol (PTP) support for MACB.

2
drivers/net/ethernet/cavium/Kconfig
View File

@ -54,7 +54,7 @@ config THUNDER_NIC_RGX
config CAVIUM_PTP
tristate "Cavium PTP coprocessor as PTP clock"
depends on 64BIT && PCI
imply PTP_1588_CLOCK
depends on PTP_1588_CLOCK
---help---
This driver adds support for the Precision Time Protocol Clocks and
Timestamping coprocessor (PTP) found on Cavium processors.

3
drivers/net/ethernet/ti/Kconfig
View File

@ -90,9 +90,8 @@ config TI_CPTS
config TI_CPTS_MOD
tristate
depends on TI_CPTS
depends on PTP_1588_CLOCK
default y if TI_CPSW=y || TI_KEYSTONE_NETCP=y || TI_CPSW_SWITCHDEV=y
select NET_PTP_CLASSIFY
imply PTP_1588_CLOCK
default m
config TI_K3_AM65_CPSW_NUSS