Re: [RFC PATCH] net: phy/mdio: enable mmd indirect access through phy_mii_ioctl()

On Wed, Nov 03, 2021 at 08:42:07PM +0200, Grygorii Strashko wrote:

On 03/11/2021 02:27, Andrew Lunn wrote:

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What i find interesting is that you and the other resent requester are
using the same user space tool. If you implement C45 over C22 in that
tool, you get your solution, and it will work for older kernels as
well. Also, given the diverse implementations of this IOTCL, it
probably works for more drivers than just those using phy_mii_ioctl().

Do you mean change uapi, like
  add mdio_phy_id_is_c45_over_c22() and
  flag #define MDIO_PHY_ID_C45_OVER_C22 0x4000?

No, i mean user space implements C45 over C22. Make phytool write
MII_MMD_CTRL and MII_MMD_DATA to perform a C45 over C22.

Now I give up - as mentioned there is now way to sync User space vs Kernel
MMD transactions and so no way to get trusted results.

Except that it will probably work 99% of the time, which is enough for
a debug tool. phylib is pretty idle most of the time, it just polls
the PHY once a second to see if the link status has changed. And does
not poll at all if interrupts are wired up. And you can always do a
read three times and see if you get the same answer, or do a write
followed by a read to see if the write actually happened correctly, or
corrupted some other register.

	Andrew