On 08/16/2016 02:37 PM, Timur Tabi wrote:

Al Stone wrote:

quoted

Does the ACPI portion of the driver*have*  to know about the PHY?  In
general,
the ACPI assumption on ARM [**] is that those have all been set up
before we
get to the kernel.  So, does it need to be visible to the ACPI part of
the
driver at all?

Yes, the driver supports both "v1" and "v2" of the PHY, and it has code
like this:

    if (adpt->phy.version == 2)
        emac_sgmii_init_v2(adpt);
    else
        emac_sgmii_init_v1(adpt);

The question, how should adpt->phy.version be initialized on device tree
and ACPI platforms?

The reason why this is confusing is because there are conflicting
perspectives of this "internal PHY".  It both is and is not part of the
EMAC.  It is a separate block in the chip, and can be replaced with
other SGMII blocks, and in the future there will be a "v3" and maybe a
"v4" or who knows what.  In fact, maybe using version numbers is
inappropriate and we'll need to use vendor names or something.

If it has self identification, and the MAC is capable of knowing what
kind of PHY it is internally bundled with, why does it matter to
represent that specific piece of information in Device Tree or ACPI?

The problem is that the internal PHY has mechanism for
self-identification.  There is no ACPI or device tree node for it. There
is no register you can query to see if it's there or what version it
is.  The MAC part of the EMAC has no knowledge of the PHY part.  The
driver just has to know it's there.

Nothing prevents you from detailing in ACPI or DT sub-components of a
larger HW block, if there is such a desire, but just make it in a way
that it looks like what would be done for e.g: separate discrete parts,
only the parenting of nodes would change.

This is why I'm advocating a separate property (DT and ACPI) to identify
the internal PHY

The truth is that I don't really care HOW it's done, and as long as we
come to a consensus soon.  I want my driver to be merged into 4.9.

-- 
Florian
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