netdev - Re: [PATCH net-next 3/3] r8169: disable RTL8126 ZRX-DC timeout

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Message-ID: <20250221200132.GA357821@bhelgaas>
Date: Fri, 21 Feb 2025 14:01:32 -0600
From: Bjorn Helgaas <helgaas@...nel.org>
To: ChunHao Lin <hau@...ltek.com>
Cc: hkallweit1@...il.com, nic_swsd@...ltek.com, andrew+netdev@...n.ch,
	davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 3/3] r8169: disable RTL8126 ZRX-DC timeout

On Fri, Feb 21, 2025 at 03:18:28PM +0800, ChunHao Lin wrote:
> Disable it due to it dose not meet ZRX-DC specification. If it is enabled,
> device will exit L1 substate every 100ms. Disable it for saving more power
> in L1 substate.

s/dose/does/

Is ZRX-DC a PCIe spec?  A Google search suggests that it might not be
completely Realtek-specific?

> +static void rtl_disable_zrxdc_timeout(struct rtl8169_private *tp)
> +{
> +	struct pci_dev *pdev = tp->pci_dev;
> +	u8 val;
> +
> +	if (pdev->cfg_size > 0x0890 &&
> +	    pci_read_config_byte(pdev, 0x0890, &val) == PCIBIOS_SUCCESSFUL &&
> +	    pci_write_config_byte(pdev, 0x0890, val & ~BIT(0)) == PCIBIOS_SUCCESSFUL)

Is this a standard PCIe extended capability?  If so, it would be nice
to search for it with pci_find_ext_capability() and use standard
#defines.

Bjorn