netdev - Re: [PATCH 14/17] r8169: Use pcie_lnkctl_clear_and

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Date: Thu, 11 May 2023 21:49:52 +0200
From: Heiner Kallweit <hkallweit1@...il.com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 linux-pci@...r.kernel.org, Bjorn Helgaas <helgaas@...nel.org>,
 Rob Herring <robh@...nel.org>, Lorenzo Pieralisi
 <lorenzo.pieralisi@....com>, Krzysztof Wilczyński
 <kw@...ux.com>, Lukas Wunner <lukas@...ner.de>, nic_swsd@...ltek.com,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 14/17] r8169: Use pcie_lnkctl_clear_and_set() for changing
 LNKCTL

On 11.05.2023 15:14, Ilpo Järvinen wrote:
> Don't assume that only the driver would be accessing LNKCTL. ASPM
> policy changes can trigger write to LNKCTL outside of driver's control.
> 
> Use pcie_lnkctl_clear_and_set() which does proper locking to avoid
> losing concurrent updates to the register value.
> 

Wouldn't it be more appropriate to add proper locking to the
underlying pcie_capability_clear_and_set_word()?

> Suggested-by: Lukas Wunner <lukas@...ner.de>
> Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> ---
>  drivers/net/ethernet/realtek/r8169_main.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index a7e376e7e689..c0294a833681 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -2686,14 +2686,12 @@ static void __rtl_ephy_init(struct rtl8169_private *tp,
>  
>  static void rtl_disable_clock_request(struct rtl8169_private *tp)
>  {
> -	pcie_capability_clear_word(tp->pci_dev, PCI_EXP_LNKCTL,
> -				   PCI_EXP_LNKCTL_CLKREQ_EN);
> +	pcie_lnkctl_clear_and_set(tp->pci_dev, PCI_EXP_LNKCTL_CLKREQ_EN, 0);
>  }
>  
>  static void rtl_enable_clock_request(struct rtl8169_private *tp)
>  {
> -	pcie_capability_set_word(tp->pci_dev, PCI_EXP_LNKCTL,
> -				 PCI_EXP_LNKCTL_CLKREQ_EN);
> +	pcie_lnkctl_clear_and_set(tp->pci_dev, 0, PCI_EXP_LNKCTL_CLKREQ_EN);
>  }
>  
>  static void rtl_pcie_state_l2l3_disable(struct rtl8169_private *tp)