RE: [PATCH net-next 1/1] r8169: enable RTL8125 ASPM L1.2

[Hau <hau@realtek.com>]

> On 24.01.2022 19:19, Chunhao Lin wrote:
> > This patch will enable RTL8125 ASPM L1.2 on the platforms that have
> > tested RTL8125 with ASPM L1.2 enabled.
> > Register mac ocp 0xc0b2 will help to identify if RTL8125 has been
> > tested on L1.2 enabled platform. If it is, this register will be set to 0xf.
> > If not, this register will be default value 0.
> >
> Who and what defines which value this register has? The BIOS? ACPI?
> Mainboard vendors test and can control the flagging? How about add-on
> cards and systems with other boot loaders, e.g. SBC's with RTL8125 like
> Odroid H2+?
>
   Soc vendor can opt-in to enable these bits to enable L1.2 through programming tool/bios/uboot.
   Right now, there is no plan for set these bits for add-on card.

> What is actually the critical component that makes L1.2 work or not with
> RTL8125 on a particular system? The chipset? Or electrical characteristics?
>
   RTL8125 can support L1.2, but it disabled by r8169. So we create an option
   to let soc vendor can opn-in to enabled L1.2 with r8169.
   
> The difference in power consumption between L1.1 and L1.2 is a few mW
> ([0]).
> So I wonder whether it's worth it to add this flagging mechanism.
> Or does it also impact reaching certain package power saving states?
> 
   Upstream port also can save power when rtl8125 L1.2 is enabled.

> [0] https://pcisig.com/making-most-pcie%C2%AE-low-power-features
> 
> > Signed-off-by: Chunhao Lin <hau@realtek.com>
> > ---
> >  drivers/net/ethernet/realtek/r8169_main.c | 99
> > ++++++++++++++++++-----
> >  1 file changed, 79 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/realtek/r8169_main.c
> > b/drivers/net/ethernet/realtek/r8169_main.c
> > index 19e2621e0645..b1e013969d4c 100644
> > --- a/drivers/net/ethernet/realtek/r8169_main.c
> > +++ b/drivers/net/ethernet/realtek/r8169_main.c
> > @@ -2238,21 +2238,6 @@ static void rtl_wol_enable_rx(struct
> rtl8169_private *tp)
> >  			AcceptBroadcast | AcceptMulticast |
> AcceptMyPhys);  }
> >
> > -static void rtl_prepare_power_down(struct rtl8169_private *tp) -{
> > -	if (tp->dash_type != RTL_DASH_NONE)
> > -		return;
> > -
> > -	if (tp->mac_version == RTL_GIGA_MAC_VER_32 ||
> > -	    tp->mac_version == RTL_GIGA_MAC_VER_33)
> > -		rtl_ephy_write(tp, 0x19, 0xff64);
> > -
> > -	if (device_may_wakeup(tp_to_dev(tp))) {
> > -		phy_speed_down(tp->phydev, false);
> > -		rtl_wol_enable_rx(tp);
> > -	}
> > -}
> > -
> >  static void rtl_init_rxcfg(struct rtl8169_private *tp)  {
> >  	switch (tp->mac_version) {
> > @@ -2650,6 +2635,34 @@ static void rtl_pcie_state_l2l3_disable(struct
> rtl8169_private *tp)
> >  	RTL_W8(tp, Config3, RTL_R8(tp, Config3) & ~Rdy_to_L23);  }
> >
> > +static void rtl_disable_exit_l1(struct rtl8169_private *tp) {
> 
> Why is this function needed? The chip should be quiet anyway.
> IOW: What could be the impact of not having this function currently?
> If it fixes something then it should be a separate patch.
> 
> > +	/* Bits control which events trigger ASPM L1 exit:
> > +	 * Bit 12: rxdv
> > +	 * Bit 11: ltr_msg
> > +	 * Bit 10: txdma_poll
> > +	 * Bit  9: xadm
> > +	 * Bit  8: pktavi
> > +	 * Bit  7: txpla
> > +	 */
> > +	switch (tp->mac_version) {
> > +	case RTL_GIGA_MAC_VER_34 ... RTL_GIGA_MAC_VER_36:
> > +		rtl_eri_clear_bits(tp, 0xd4, 0x1f00);
> > +		break;
> > +	case RTL_GIGA_MAC_VER_37 ... RTL_GIGA_MAC_VER_38:
> > +		rtl_eri_clear_bits(tp, 0xd4, 0x0c00);
> > +		break;
> > +	case RTL_GIGA_MAC_VER_40 ... RTL_GIGA_MAC_VER_53:
> > +		rtl_eri_clear_bits(tp, 0xd4, 0x1f80);
> > +		break;
> > +	case RTL_GIGA_MAC_VER_60 ... RTL_GIGA_MAC_VER_63:
> > +		r8168_mac_ocp_modify(tp, 0xc0ac, 0x1f80, 0);
> > +		break;
> > +	default:
> > +		break;
> > +	}
> > +}
> > +
> >  static void rtl_enable_exit_l1(struct rtl8169_private *tp)  {
> >  	/* Bits control which events trigger ASPM L1 exit:
> > @@ -2692,6 +2705,33 @@ static void rtl_hw_aspm_clkreq_enable(struct
> rtl8169_private *tp, bool enable)
> >  	udelay(10);
> >  }
> >
> > +static void rtl_hw_aspm_l12_enable(struct rtl8169_private *tp, bool
> > +enable) {
> 
> I assume this code works on RTL8125 only. Then this should be reflected in
> the function naming, like we do it for other version-specific functions.
> 
> > +	/* Don't enable L1.2 in the chip if OS can't control ASPM */
> > +	if (enable && tp->aspm_manageable) {
> > +		r8168_mac_ocp_modify(tp, 0xe094, 0xff00, 0);
> > +		r8168_mac_ocp_modify(tp, 0xe092, 0x00ff, BIT(2));
> > +	} else {
> > +		r8168_mac_ocp_modify(tp, 0xe092, 0x00ff, 0);
> > +	}
> > +}
> > +
> > +static void rtl_prepare_power_down(struct rtl8169_private *tp) {
> > +	if (tp->dash_type != RTL_DASH_NONE)
> > +		return;
> > +
> > +	if (tp->mac_version == RTL_GIGA_MAC_VER_32 ||
> > +	    tp->mac_version == RTL_GIGA_MAC_VER_33)
> > +		rtl_ephy_write(tp, 0x19, 0xff64);
> > +
> > +	if (device_may_wakeup(tp_to_dev(tp))) {
> > +		rtl_disable_exit_l1(tp);
> > +		phy_speed_down(tp->phydev, false);
> > +		rtl_wol_enable_rx(tp);
> > +	}
> > +}
> > +
> >  static void rtl_set_fifo_size(struct rtl8169_private *tp, u16 rx_stat,
> >  			      u16 tx_stat, u16 rx_dyn, u16 tx_dyn)  { @@ -
> 3675,6 +3715,7
> > @@ static void rtl_hw_start_8125b(struct rtl8169_private *tp)
> >  	rtl_ephy_init(tp, e_info_8125b);
> >  	rtl_hw_start_8125_common(tp);
> >
> > +	rtl_hw_aspm_l12_enable(tp, true);
> >  	rtl_hw_aspm_clkreq_enable(tp, true);  }
> >
> > @@ -5255,6 +5296,20 @@ static void rtl_init_mac_address(struct
> rtl8169_private *tp)
> >  	rtl_rar_set(tp, mac_addr);
> >  }
> >
> > +/* mac ocp 0xc0b2 will help to identify if RTL8125 has been tested
> > + * on L1.2 enabled platform. If it is, this register will be set to 0xf.
> > + * If not, this register will be default value 0.
> > + */
> > +static bool rtl_platform_l12_enabled(struct rtl8169_private *tp) {
> 
> The function name is misleading. It could be read as checking whether the
> platform supports L1.2.
> 
> > +	switch (tp->mac_version) {
> > +	case RTL_GIGA_MAC_VER_60 ... RTL_GIGA_MAC_VER_63:
> > +		return (r8168_mac_ocp_read(tp, 0xc0b2) & 0xf) ? true : false;
> > +	default:
> > +		return false;
> > +	}
> > +}
> > +
> >  static int rtl_init_one(struct pci_dev *pdev, const struct
> > pci_device_id *ent)  {
> >  	struct rtl8169_private *tp;
> > @@ -5333,11 +5388,15 @@ static int rtl_init_one(struct pci_dev *pdev,
> const struct pci_device_id *ent)
> >  	 * Chips from RTL8168h partially have issues with L1.2, but seem
> >  	 * to work fine with L1 and L1.1.
> >  	 */
> > -	if (tp->mac_version >= RTL_GIGA_MAC_VER_45)
> > -		rc = pci_disable_link_state(pdev, PCIE_LINK_STATE_L1_2);
> > -	else
> > -		rc = pci_disable_link_state(pdev, PCIE_LINK_STATE_L1);
> > -	tp->aspm_manageable = !rc;
> > +	if (!rtl_platform_l12_enabled(tp)) {
> > +		if (tp->mac_version >= RTL_GIGA_MAC_VER_45)
> > +			rc = pci_disable_link_state(pdev,
> PCIE_LINK_STATE_L1_2);
> > +		else
> > +			rc = pci_disable_link_state(pdev,
> PCIE_LINK_STATE_L1);
> > +		tp->aspm_manageable = !rc;
> > +	} else {
> > +		tp->aspm_manageable = pcie_aspm_enabled(pdev);
> > +	}
> >
> 
> Better readable may be the following:
> 
> if (rtl_platform_l12_enabled(tp)) {
> 	tp->aspm_manageable = pcie_aspm_enabled(pdev); } else if (tp-
> >mac_version >= RTL_GIGA_MAC_VER_45) {
> 	rc = pci_disable_link_state(pdev, PCIE_LINK_STATE_L1_2);
> 	tp->aspm_manageable = !rc;
> } else {
> 	rc = pci_disable_link_state(pdev, PCIE_LINK_STATE_L1);
> 	tp->aspm_manageable = !rc;
> }
> 
> >  	tp->dash_type = rtl_check_dash(tp);
> >
> 
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