Re: [PATCH v1 net-next] net: phy: Drop #inclusion of <linux/mod_devicetable.h> from <linux/mdio.h>

["Uwe Kleine-König (The Capable Hub)" <u.kleine-koenig@baylibre.com>]

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Hello Andrew,

On Mon, Jul 06, 2026 at 04:17:47PM +0200, Andrew Lunn wrote:
> On Mon, Jul 06, 2026 at 11:29:19AM +0200, Uwe Kleine-König (The Capable Hub) wrote:
> > <linux/mdio.h> itself doesn't use any of the device id structures. The
> > files #including <linux/mdio.h> use a variety of them:
> > 
> > 	$ git grep -l '<linux/mdio.h>' | xargs grep --color  -E '\<(acpi_device_id|amba_id|ap_device_id|apr_device_id|auxiliary_device_id|bcma_device_id|ccw_device_id|cdx_device_id|coreboot_device_id|css_device_id|dfl_device_id|dmi_(device|system)_id|eisa_device_id|fsl_mc_device_id|hda_device_id|hid_device_id|hv_vmbus_device_id|i2c_device_id|i3c_device_id|ieee1394_device_id|input_device_id|ipack_device_id|isapnp_device_id|ishtp_device_id|mcb_device_id|mdio_device_id|mei_cl_device_id|mhi_device_id|mips_cdmm_device_id|of_device_id|parisc_device_id|pci_device_id|pci_epf_device_id|pcmcia_device_id|platform_device_id|pnp_(card_)?device_id|rio_device_id|rpmsg_device_id|sdio_device_id|sdw_device_id|serio_device_id|slim_device_id|spi_device_id|spmi_device_id|ssam_device_id|ssb_device_id|tb_service_id|tee_client_device_id|typec_device_id|ulpi_device_id|usb_device_id|vchiq_device_id|virtio_device_id|wmi_device_id|x86_(cpu|device)_id|zorro_device_id|cpu_feature)\>'
> > 	...
> > 
> > but none of them relies on <linux/mdio.h>'s #include.
> > 
> > <linux/mod_devicetable.h> is a bad header mixing many different device
> > id structures and thus is an unfortunate dependency because if e.g.
> > struct wmi_device_id is modified all users of <linux/mdio.h> need to be
> > recompiled despite none of them using struct wmi_device_id.
> > 
> > So drop the unused header.
> 
> While i agree that there are lots of unneeded dependencies here, does
> this change actually solve anything? Pretty much every PHY driver
> needs mdio_device_id, which is part of mod_devicetable.h. So it must
> be getting included somehow.
> 
> I assume the long term plan is to move all the structure definitions
> out of mod_devicetable.h, so a driver can include just the ones it
> needs?

Yes, however not long term, but I intend to get most of this done for
7.3-rc1.

> Is this patch somehow a step along that path? Why not move
> mdio_device_id into mod_devicetable_mdio.h and include that? It seems
> like the more obvious fix.

That's exactly my thought, and there is commit ad428f5811bd
("mod_devicetable.h: Split into per subsystem headers") that is part of
v7.2-rc2 and that does exactly that (apart from the filename).

Best regards
Uwe

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