Re: [PATCH net-next v3 4/9] net: stmmac: qcom-ethqos: fix RGMII_ID mode to use DLL bypass

[Mohd Ayaan Anwar <mohd.anwar@oss.qualcomm.com>]

On Sat, Oct 17, 2026 at 04:00:27PM +0200, Andrew Lunn wrote:
> On Sat, Oct 17, 2026 at 03:15:15PM +0530, Mohd Ayaan Anwar wrote:
> > When "rgmii-id" is selected the PHY supplies both TX and RX delays, so
> > the MAC must not add its own. The driver currently falls through to the
> > generic DLL initialisation path which programs it to add a delay.
> > 
> > Power down the DLL and set DDR bypass mode for RGMII_ID, then program
> > the IO_MACRO via a new ethqos_rgmii_id_macro_init() helper. Also fix
> > ethqos_set_clk_tx_rate() to not double the clock rate in bypass mode at
> > 100M/10M, and remove RGMII_ID from the phase-shift suppression in
> > ethqos_rgmii_macro_init() since RGMII_ID no longer reaches that path.
> 
> How many different boards have you tested this on? How confident are
> you there will not be regressions?
> 

Apart from the new compatible, I have tested this on three different
board designs of the QCS615 SoC. The EMAC on it is identical to the
"qcom,qcs404-ethqos" version. Two of the boards have the Microchip
KSZ9031 PHY while the third has the TI DP83867 PHY.

> Since you are adding a new compatible "qcom,shikra-ethqos", you could
> limit the change in behaviour to just this.
> 

That sounds like a better idea. I will restrict the new sequence to just
"qcom,shikra-ethqos" and "qcom,qcs404-ethqos" using something like
data->phy_managed_delays = true. I will change the warning patch to also
check for this boolean, so any users of "qcom,qcs404-ethqos" can be
notified.

The two other RGMII designs ("qcom,qcs404-ethqos" and
"qcom,sc8280xp-ethqos") can continue using the legacy flow.

	Ayaan