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

[Vladimir Oltean]

Hi Sean,

On Fri, Aug 11, 2023 at 07:36:37PM +0300, Vladimir Oltean wrote:
> Let me explain that approach, because your mention of "swapping out the
> bootloaders" makes it appear as if you are not visualising what I am
> proposing.
> 
> The Lynx SerDes family has 2 PLLs, and more lanes (4 or 8). Each lane
> uses one PLL or the other, to derive its protocol frequency. Through the
> RCW, you provision the 2 PLL frequencies that may be used by the lanes
> at runtime.
> 
> The Lynx 28G SerDes driver reads the PLL frequencies in
> lynx_28g_pll_read_configuration(), and determines the interface modes
> supportable by each PLL (this is used by phylink). But it never changes
> those PLL frequencies, since that operation is practically impossible in
> the general sense (PLLs are shared by multiple lanes, so changing a PLL
> frequency disrupts all lanes that use it).

Is my high-level feedback clear and actionable to you? I am suggesting
to keep the look and feel the same between the lynx-10g and lynx-28g
drivers, and to not use "fsl,type" protocols listed in the device tree
as the immutable source of information for populating mode->protos, but
instead the current PLL frequency configuration. So this implies that I
am requesting that the dt-bindings should not contain a listing of the
supported protocols.