netdev - Re: [PATCH] r8169: skip DASH fw status checks when DASH is disabled

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Date: Fri, 22 Mar 2024 08:01:40 +0100
From: Heiner Kallweit <hkallweit1@...il.com>
To: pseudoc <atlas.yu@...onical.com>, nic_swsd@...ltek.com,
 davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
 pabeni@...hat.com, ChunHao Lin <hau@...ltek.com>
Cc: netdev@...r.kernel.org
Subject: Re: [PATCH] r8169: skip DASH fw status checks when DASH is disabled

On 22.03.2024 04:46, pseudoc wrote:
> On devices that support DASH, the current code in the "rtl_loop_wait" function
> raises false alarms when DASH is disabled. This occurs because the function
> attempts to wait for the DASH firmware to be ready, even though it's not
> relevant in this case.
> 

To me this seems to be somewhat in conflict with the commit message of the
original change. There's a statement that DASH firmware may influence driver
behavior even if DASH is disabled.
I think we have to consider three cases in the driver:
1. DASH enabled (implies firmware is present)
2. DASH disabled (firmware present)
3. DASH disabled (no firmware)

I assume your change is for case 3.

Is there a way to detect firmware presence on driver load?

> r8169 0000:0c:00.0 eth0: RTL8168ep/8111ep, 38:7c:76:49:08:d9, XID 502, IRQ 86
> r8169 0000:0c:00.0 eth0: jumbo features [frames: 9194 bytes, tx checksumming: ko]
> r8169 0000:0c:00.0 eth0: DASH disabled
> ...
> r8169 0000:0c:00.0 eth0: rtl_ep_ocp_read_cond == 0 (loop: 30, delay: 10000).
> 
> This patch modifies the driver start/stop functions to skip checking the DASH
> firmware status when DASH is explicitly disabled. This prevents unnecessary
> delays and false alarms.
> 
> The patch has been tested on several ThinkStation P8/PX workstations.
> 
> Fixes: 0ab0c45d8aae ("r8169: add handling DASH when DASH is disabled")

SoB is missing

> ---
>  drivers/net/ethernet/realtek/r8169_main.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/ethernet/realtek/r8169_main.c b/drivers/net/ethernet/realtek/r8169_main.c
> index 5c879a5c86d7..a39520a3f41d 100644
> --- a/drivers/net/ethernet/realtek/r8169_main.c
> +++ b/drivers/net/ethernet/realtek/r8169_main.c
> @@ -1317,6 +1317,8 @@ static void rtl8168ep_stop_cmac(struct rtl8169_private *tp)
>  static void rtl8168dp_driver_start(struct rtl8169_private *tp)
>  {
>  	r8168dp_oob_notify(tp, OOB_CMD_DRIVER_START);
> +	if (!tp->dash_enabled)
> +		return;
>  	rtl_loop_wait_high(tp, &rtl_dp_ocp_read_cond, 10000, 10);
>  }
>  
> @@ -1324,6 +1326,8 @@ static void rtl8168ep_driver_start(struct rtl8169_private *tp)
>  {
>  	r8168ep_ocp_write(tp, 0x01, 0x180, OOB_CMD_DRIVER_START);
>  	r8168ep_ocp_write(tp, 0x01, 0x30, r8168ep_ocp_read(tp, 0x30) | 0x01);
> +	if (!tp->dash_enabled)
> +		return;
>  	rtl_loop_wait_high(tp, &rtl_ep_ocp_read_cond, 10000, 30);
>  }
>  
> @@ -1338,6 +1342,8 @@ static void rtl8168_driver_start(struct rtl8169_private *tp)
>  static void rtl8168dp_driver_stop(struct rtl8169_private *tp)
>  {
>  	r8168dp_oob_notify(tp, OOB_CMD_DRIVER_STOP);
> +	if (!tp->dash_enabled)
> +		return;
>  	rtl_loop_wait_low(tp, &rtl_dp_ocp_read_cond, 10000, 10);
>  }
>  
> @@ -1346,6 +1352,8 @@ static void rtl8168ep_driver_stop(struct rtl8169_private *tp)
>  	rtl8168ep_stop_cmac(tp);
>  	r8168ep_ocp_write(tp, 0x01, 0x180, OOB_CMD_DRIVER_STOP);
>  	r8168ep_ocp_write(tp, 0x01, 0x30, r8168ep_ocp_read(tp, 0x30) | 0x01);
> +	if (!tp->dash_enabled)
> +		return;
>  	rtl_loop_wait_low(tp, &rtl_ep_ocp_read_cond, 10000, 10);
>  }
>