[PATCH v14 00/15] phy: Add support for Lynx 10G SerDes

Sean Anderson sean.anderson at seco.com
Sat Aug 12 01:43:01 AEST 2023

On 8/11/23 11:08, Vladimir Oltean wrote:
> Hi Sean,
> On Tue, Jun 13, 2023 at 05:27:54PM +0300, Vladimir Oltean wrote:
>> > > At first sight you might appear to have a point related to the fact that
>> > > PLL register writes are necessary, and thus this whole shebang is necessary.
>> > > But this can all be done using PBI commands, with the added benefit that
>> > > U-Boot can also use those SERDES networking ports, and not just Linux.
>> > > You can use the RCW+PBL specific to your board to inform the SoC that
>> > > your platform's refclk 1 is 156 MHz (something which the reset state
>> > > machine seems unable to learn, with protocol 0x3333). You don't have to
>> > > put that in the device tree. You don't have to push code to any open
>> > > source project to expose your platform specific details. Then, just like
>> > > in the case of the Lynx 28G driver on LX2160, the SERDES driver could
>> > > just treat the PLL configuration as read-only, which would greatly
>> > > simplify things and eliminate the need for a clk driver.
>> > > 
>> > > Here is an illustrative example (sorry, I don't have a board with the
>> > > right refclk on that PLL, to verify all the way):
>> > > 
>> > > ... snip ...
>> > 
>> > (which of course complicates the process of building the PBIs...)
>> Maybe this is the language barrier, but what are you trying to say here?
> I said that I don't understand. Can you please clarify what you were
> trying to transmit with this comment?

Well, right now I produce my RCWs by generating a second RCW with e.g.
1133 replaced by 3333. But doing this is a more involved change. Just a
minor issue, really. That said, I don't think this is the best approach
moving forward. Much like many other platforms, users should be able to
plug in an SFP module and Linux should configure things appropriately.
An RCW approach requires some kind of configuration tool to swap out the
bootloaders, which isn't as good of a user experience.


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