Messages in this thread | | | Date | Fri, 31 Mar 2023 12:12:19 +0100 | From | "Russell King (Oracle)" <> | Subject | Re: [PATCH net-next 2/2] net: ethernet: ti: am65-cpsw: Enable USXGMII mode for J784S4 CPSW9G |
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On Fri, Mar 31, 2023 at 04:23:16PM +0530, Siddharth Vadapalli wrote: > > > On 31/03/23 15:16, Russell King (Oracle) wrote: > > On Fri, Mar 31, 2023 at 02:55:56PM +0530, Siddharth Vadapalli wrote: > >> Russell, > >> > >> On 31/03/23 13:54, Russell King (Oracle) wrote: > >>> On Fri, Mar 31, 2023 at 01:35:10PM +0530, Siddharth Vadapalli wrote: > >>>> Hello Russell, > >>>> > >>>> Thank you for reviewing the patch. > >>>> > >>>> On 31/03/23 13:27, Russell King (Oracle) wrote: > >>>>> On Fri, Mar 31, 2023 at 12:21:10PM +0530, Siddharth Vadapalli wrote: > >>>>>> TI's J784S4 SoC supports USXGMII mode. Add USXGMII mode to the > >>>>>> extra_modes member of the J784S4 SoC data. Additionally, configure the > >>>>>> MAC Control register for supporting USXGMII mode. Also, for USXGMII > >>>>>> mode, include MAC_5000FD in the "mac_capabilities" member of struct > >>>>>> "phylink_config". > >>>>> > >>>>> I don't think TI "get" phylink at all... > >>>>> > >>>>>> diff --git a/drivers/net/ethernet/ti/am65-cpsw-nuss.c b/drivers/net/ethernet/ti/am65-cpsw-nuss.c > >>>>>> index 4b4d06199b45..ab33e6fe5b1a 100644 > >>>>>> --- a/drivers/net/ethernet/ti/am65-cpsw-nuss.c > >>>>>> +++ b/drivers/net/ethernet/ti/am65-cpsw-nuss.c > >>>>>> @@ -1555,6 +1555,8 @@ static void am65_cpsw_nuss_mac_link_up(struct phylink_config *config, struct phy > >>>>>> mac_control |= CPSW_SL_CTL_GIG; > >>>>>> if (interface == PHY_INTERFACE_MODE_SGMII) > >>>>>> mac_control |= CPSW_SL_CTL_EXT_EN; > >>>>>> + if (interface == PHY_INTERFACE_MODE_USXGMII) > >>>>>> + mac_control |= CPSW_SL_CTL_XGIG | CPSW_SL_CTL_XGMII_EN; > >>>>> > >>>>> The configuration of the interface mode should *not* happen in > >>>>> mac_link_up(), but should happen in e.g. mac_config(). > >>>> > >>>> I will move all the interface mode associated configurations to mac_config() in > >>>> the v2 series. > >>> > >>> Looking at the whole of mac_link_up(), could you please describe what > >>> effect these bits are having: > >>> > >>> CPSW_SL_CTL_GIG > >>> CPSW_SL_CTL_EXT_EN > >>> CPSW_SL_CTL_IFCTL_A > >> > >> CPSW_SL_CTL_GIG corresponds to enabling Gigabit mode (full duplex only). > >> CPSW_SL_CTL_EXT_EN when set enables in-band mode of operation and when cleared > >> enables forced mode of operation. > >> CPSW_SL_CTL_IFCTL_A is used to set the RMII link speed (0=10 mbps, 1=100 mbps). > > > > Okay, so I would do in mac_link_up(): > > > > /* RMII needs to be manually configured for 10/100Mbps */ > > if (interface == PHY_INTERFACE_MODE_RMII && speed == SPEED_100) > > mac_control |= CPSW_SL_CTL_IFCTL_A; > > > > if (speed == SPEED_1000) > > mac_control |= CPSW_SL_CTL_GIG; > > if (duplex) > > mac_control |= CPSW_SL_CTL_FULLDUPLEX; > > > > I would also make mac_link_up() do a read-modify-write operation to > > only affect the bits that it is changing. > > This is the current implementation except for the SGMII mode associated > operation that I had recently added. I will fix that. Also, the > cpsw_sl_ctl_set() function which writes the mac_control value performs a read > modify write operation. > > > > > Now, for SGMII, I would move setting CPSW_SL_CTL_EXT_EN to mac_config() > > to enable in-band mode - don't we want in-band mode enabled all the > > time while in SGMII mode so the PHY gets the response from the MAC? > > Thank you for pointing it out. I will move that to mac_config(). > > > > > Lastly, for RGMII at 10Mbps, you seem to suggest that you need RGMII > > in-band mode enabled for that - but if you need RGMII in-band for > > 10Mbps, wouldn't it make sense for the other speeds as well? If so, > > wouldn't that mean that CPSW_SL_CTL_EXT_EN can always be set for > > RGMII no matter what speed is being used? > > The CPSW MAC does not support forced mode at 10 Mbps RGMII. For this reason, if > RGMII 10 Mbps is requested, it is set to in-band mode.
What I'm saying is that if we have in-band signalling that is reliable for a particular interface mode, why not always use it, rather than singling out one specific speed as an exception? Does it not work in 100Mbps and 1Gbps?
-- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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