Re: [PATCH net-next v9 3/5] r8169: Consider chip-specific ASPM can be enabled on more cases

[Sathyanarayanan Kuppuswamy <sathyanarayanan.kuppuswamy@linux.intel.com>]

On 2/24/23 7:46 PM, Kai-Heng Feng wrote:
> To really enable ASPM on r8169 NICs, both standard PCIe ASPM and
> chip-specific ASPM have to be enabled at the same time.
> 
> Before enabling ASPM at chip side, make sure the following conditions
> are met:
> 1) Use pcie_aspm_support_enabled() to check if ASPM is disabled by
>    kernel parameter.
> 2) Use pcie_aspm_capable() to see if the device is capable to perform
>    PCIe ASPM.

Why not club the support check within pcie_aspm_capable()?

> 3) Check the return value of pci_disable_link_state(). If it's -EPERM,
>    it means BIOS doesn't grant ASPM control to OS, and device should use
>    the ASPM setting as is.
> 
> Consider ASPM is manageable when those conditions are met.
> 
> While at it, disable ASPM at chip-side for TX timeout reset, since
> pci_disable_link_state() doesn't have any effect when OS isn't granted
> with ASPM control.
> 
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
> ---
> v9:
>  - No change.
> 
> v8:
>  - Enable chip-side ASPM only when PCIe ASPM is already available.
>  - Wording.
> 
> v7:
>  - No change.
> 
> v6:
>  - Unconditionally enable chip-specific ASPM.
> 
> v5:
>  - New patch.
> 
>  drivers/net/ethernet/realtek/r8169_main.c | 22 ++++++++++++++++++----
>  1 file changed, 18 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index 45147a1016bec..a857650c2e82b 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -2675,8 +2675,11 @@ static void rtl_disable_exit_l1(struct rtl8169_private *tp)
>  
>  static void rtl_hw_aspm_clkreq_enable(struct rtl8169_private *tp, bool enable)
>  {
> -	/* Don't enable ASPM in the chip if OS can't control ASPM */
> -	if (enable && tp->aspm_manageable) {
> +	/* Skip if PCIe ASPM isn't possible */
> +	if (!tp->aspm_manageable)
> +		return;
> +
> +	if (enable) {
>  		RTL_W8(tp, Config5, RTL_R8(tp, Config5) | ASPM_en);
>  		RTL_W8(tp, Config2, RTL_R8(tp, Config2) | ClkReqEn);
>  
> @@ -4545,8 +4548,13 @@ static void rtl_task(struct work_struct *work)
>  		/* ASPM compatibility issues are a typical reason for tx timeouts */
>  		ret = pci_disable_link_state(tp->pci_dev, PCIE_LINK_STATE_L1 |
>  							  PCIE_LINK_STATE_L0S);
> +
> +		/* OS may not be granted to control PCIe ASPM, prevent the driver from using it */
> +		tp->aspm_manageable = 0;
> +
>  		if (!ret)
>  			netdev_warn_once(tp->dev, "ASPM disabled on Tx timeout\n");
> +
>  		goto reset;
>  	}
>  
> @@ -5227,13 +5235,19 @@ 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 (rtl_aspm_is_safe(tp))
> +	if (!pcie_aspm_support_enabled() || !pcie_aspm_capable(pdev))
> +		rc = -EINVAL;
> +	else if (rtl_aspm_is_safe(tp))
>  		rc = 0;
>  	else if (tp->mac_version >= RTL_GIGA_MAC_VER_46)
>  		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;
> +
> +	/* -EPERM means BIOS doesn't grant OS ASPM control, ASPM should be use
> +	 * as is. Honor it.
> +	 */
> +	tp->aspm_manageable = (rc == -EPERM) ? 1 : !rc;
>  
>  	tp->dash_type = rtl_check_dash(tp);
>  

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer