Re: [PATCH v5 net-next 04/13] net: enetc: add initial netc-blk-ctrl driver support

On Fri, Oct 25, 2024 at 04:44:50AM +0300, Wei Fang wrote:

quoted

On Thu, Oct 24, 2024 at 02:53:19PM +0800, Wei Fang wrote:
Can U-Boot deal with the IERB/PRB configuration?

For LS1028A, the platform which initiated the IERB driver "trend", the situation
was a bit more complicated, as we realized the reset-time defaults aren't what
we need very late in the product life cycle, when customer boards already had
bootloaders and we didn't want to complicate their process to have to redeploy
in order to get access to such a basic feature as flow control. Though if we knew
it from day one, we would have put the IERB fixups in U-Boot.

The situation of i.MX95 is different from LS1028A, i.MX95 needs to support system
suspend/resume feature. If the i.MX95 enters suspend mode, the NETC may
power off (depends on user case), so IERB and PRB will be reset, in this case, we need
to reconfigure the IERB & PRB, including NETCMIX.

quoted

What is written in the IERB for MII/PCS protocols by default? I suppose there's
some other mechanism to preinitialize it with good values?

The MII/PCS protocols are set in NETCMIX not IERB, but the IERB will get these
info from NETCMIX, I mean the hardware, not the software. The default values
are all 0.

I am shocked that the NETCMIX/IERB blocks does not have a separate power
domain from the ENETC, to avoid powering them off, which loses the settings.
Please provide this explanation in the opening comments of this driver, it
is its entire "raison d'être".