linux-kernel - Re: [PATCH v5 7/7] r8169: Coalesce mac ocp write and modify for rtl_hw_init

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Date:   Mon, 30 Oct 2023 15:03:59 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>,
        Jason Gunthorpe <jgg@...pe.ca>, Joerg Roedel <jroedel@...e.de>,
        Lu Baolu <baolu.lu@...ux.intel.com>, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>, 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>, Marco Elver <elver@...gle.com>
Subject: Re: [PATCH v5 7/7] r8169: Coalesce mac ocp write and modify for
 rtl_hw_init_8125 to reduce spinlock contention

On 29.10.2023 19:36, Mirsad Goran Todorovac wrote:
> Repeated calls to r8168_mac_ocp_write() and r8168_mac_ocp_modify() in
> the init sequence of the 8125 involve implicit spin_lock_irqsave() and
> spin_unlock_irqrestore() on each invocation.
> 
> Coalesced with the corresponding helpers r8168_mac_ocp_write_seq() and
> r8168_mac_ocp_modify_seq() into sequential write or modidy with a sinqle
> pair of spin_lock_irqsave() and spin_unlock_irqrestore(), these calls
> reduce overall lock contention.
> 
> Fixes: f1bce4ad2f1ce ("r8169: add support for RTL8125")
> Cc: Heiner Kallweit <hkallweit1@...il.com>
> Cc: Marco Elver <elver@...gle.com>
> Cc: nic_swsd@...ltek.com
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: Eric Dumazet <edumazet@...gle.com>
> Cc: Jakub Kicinski <kuba@...nel.org>
> Cc: Paolo Abeni <pabeni@...hat.com>
> Cc: netdev@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Link: https://lore.kernel.org/lkml/20231028005153.2180411-1-mirsad.todorovac@alu.unizg.hr/
> Link: https://lore.kernel.org/lkml/20231028110459.2644926-1-mirsad.todorovac@alu.unizg.hr/
> Signed-off-by: Mirsad Goran Todorovac <mirsad.todorovac@....unizg.hr>
> ---
> v5:
>  added unlocked primitives to allow mac ocs modify grouping
>  applied coalescing of mac ocp writes/modifies for 8168ep and 8117
>  some formatting fixes to please checkpatch.pl
> 
> v4:
>  fixed complaints as advised by Heiner and checkpatch.pl
>  split the patch into five sections to be more easily manipulated and reviewed
>  introduced r8168_mac_ocp_write_seq()
>  applied coalescing of mac ocp writes/modifies for 8168H, 8125 and 8125B
> 
> v3:
>  removed register/mask pair array sentinels, so using ARRAY_SIZE().
>  avoided duplication of RTL_W32() call code as advised by Heiner.
> 
>  drivers/net/ethernet/realtek/r8169_main.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index 0778cd0ba2e0..76f0f1e13909 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -5089,6 +5089,12 @@ static void rtl_hw_init_8168g(struct rtl8169_private *tp)
>  
>  static void rtl_hw_init_8125(struct rtl8169_private *tp)
>  {
> +	static const struct e_info_regdata hw_init_8125_1[] = {
> +		{ 0xc0aa, 0x07d0 },
> +		{ 0xc0a6, 0x0150 },
> +		{ 0xc01e, 0x5555 },
> +	};
> +
>  	rtl_enable_rxdvgate(tp);
>  
>  	RTL_W8(tp, ChipCmd, RTL_R8(tp, ChipCmd) & ~(CmdTxEnb | CmdRxEnb));
> @@ -5098,9 +5104,7 @@ static void rtl_hw_init_8125(struct rtl8169_private *tp)
>  	r8168_mac_ocp_modify(tp, 0xe8de, BIT(14), 0);
>  	r8168g_wait_ll_share_fifo_ready(tp);
>  
> -	r8168_mac_ocp_write(tp, 0xc0aa, 0x07d0);
> -	r8168_mac_ocp_write(tp, 0xc0a6, 0x0150);
> -	r8168_mac_ocp_write(tp, 0xc01e, 0x5555);
> +	r8168_mac_ocp_write_seq(tp, hw_init_8125_1);
>  	r8168g_wait_ll_share_fifo_ready(tp);
>  }
>  
As for few other patches in the series, not really worth it.