netdev - Re: [PATCH net v4 4/5] net: dsa: microchip: use collision based back pressure mode

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Date: Mon, 3 Jun 2024 03:23:21 +0000
From: <Arun.Ramadoss@...rochip.com>
To: <enguerrand.de-ribaucourt@...oirfairelinux.com>, <netdev@...r.kernel.org>
CC: <linux@...linux.org.uk>, <Woojung.Huh@...rochip.com>,
	<hkallweit1@...il.com>, <UNGLinuxDriver@...rochip.com>, <andrew@...n.ch>
Subject: Re: [PATCH net v4 4/5] net: dsa: microchip: use collision based back
 pressure mode

Hi Enguerrand,

> 
> diff --git a/drivers/net/dsa/microchip/ksz9477.c
> b/drivers/net/dsa/microchip/ksz9477.c
> index f8ad7833f5d9..343b9d7538e9 100644
> --- a/drivers/net/dsa/microchip/ksz9477.c
> +++ b/drivers/net/dsa/microchip/ksz9477.c
> @@ -1299,6 +1299,9 @@ int ksz9477_setup(struct dsa_switch *ds)
>         /* Enable REG_SW_MTU__2 reg by setting SW_JUMBO_PACKET */
>         ksz_cfg(dev, REG_SW_MAC_CTRL_1, SW_JUMBO_PACKET, true);
> 
> +       /* Use collision based back pressure mode. */
> +       ksz_cfg(dev, REG_SW_MAC_CTRL_1, SW_BACK_PRESSURE, false);

nitpick: Comment says use collision based back pressure mode, but in
the register write we are clearing it (false). From the datasheet, it
mentions 1 - Carrier based back pressure 0 - Collision based back
pressure. Instead of false, we can have macros like below or something
similar

#define SW_BACK_PRESSURE_COLLISION 0

> +
>         /* Now we can configure default MTU value */
>         ret = regmap_update_bits(ksz_regmap_16(dev), REG_SW_MTU__2,
> REG_SW_MTU_MASK,
>                                  VLAN_ETH_FRAME_LEN + ETH_FCS_LEN);
> --
> 2.34.1
>