On Wed, May 19, 2021 at 08:45:21AM -0400, Peter Geis wrote:

On Wed, May 19, 2021 at 7:50 AM Leon Romanovsky [off-list ref] wrote:

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On Wed, May 19, 2021 at 12:37:43PM +0200, Heiner Kallweit wrote:

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On 19.05.2021 10:18, Leon Romanovsky wrote:

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On Tue, May 18, 2021 at 08:20:03PM -0400, Peter Geis wrote:

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On Tue, May 18, 2021 at 4:59 AM Leon Romanovsky [off-list ref] wrote:

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On Tue, May 11, 2021 at 05:46:06PM -0400, Peter Geis wrote:

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Add a driver for the Motorcomm yt8511 phy that will be used in the
production Pine64 rk3566-quartz64 development board.
It supports gigabit transfer speeds, rgmii, and 125mhz clk output.

Signed-off-by: Peter Geis <redacted>
---
 MAINTAINERS                 |  6 +++
 drivers/net/phy/Kconfig     |  6 +++
 drivers/net/phy/Makefile    |  1 +
 drivers/net/phy/motorcomm.c | 85 +++++++++++++++++++++++++++++++++++++
 4 files changed, 98 insertions(+)
 create mode 100644 drivers/net/phy/motorcomm.c

<...>

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+static const struct mdio_device_id __maybe_unused motorcomm_tbl[] = {
+     { PHY_ID_MATCH_EXACT(PHY_ID_YT8511) },
+     { /* sentinal */ }
+}

Why is this "__maybe_unused"? This *.c file doesn't have any compilation option
to compile part of it.

The "__maybe_unused" is not needed in this case.

I was simply following convention, for example the realtek.c,
micrel.c, and smsc.c drivers all have this as well.

Maybe they have a reason, but this specific driver doesn't have such.

It's used like this:
MODULE_DEVICE_TABLE(mdio, <mdio_device_id_tbl>);

And MODULE_DEVICE_TABLE is a no-op if MODULE isn't defined:

#ifdef MODULE
/* Creates an alias so file2alias.c can find device table. */
#define MODULE_DEVICE_TABLE(type, name)                                       \
extern typeof(name) __mod_##type##__##name##_device_table             \
  __attribute__ ((unused, alias(__stringify(name))))
#else  /* !MODULE */
#define MODULE_DEVICE_TABLE(type, name)
#endif

In this case the table is unused.

Do you see compilation warning for such scenario?

The issue you are describing has been fixed since 2010:

commit cf93c94581bab447a5634c6d737c1cf38c080261
Author: Uwe Kleine-König [off-list ref]
Date:   Sun Oct 3 23:43:32 2010 +0000

    net/phy: fix many "defined but unused" warnings

    MODULE_DEVICE_TABLE only expands to something if it's compiled
    for a module.  So when building-in support for the phys, the
    mdio_device_id tables are unused.  Marking them with __maybe_unused
    fixes the following warnings:

There is a strong push to fix all warnings during build, including W=1 warnings.
For fun I rebuilt without module support and confirmed that removing
this does trigger a W=1 warning.

I'm sorry that I continue to ask, but is net/phy/* usable without MODULE?
If not, the better fix is to require it in Kconfig instead of fixing all drivers.

Thanks for your answers.

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Thanks

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Thanks

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Thanks