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Message-ID: <0da58722ba9e451b984f8c10bb3bb04b2725d6a2.camel@microchip.com>
Date: Thu, 3 Nov 2022 10:57:08 +0000
From: <Arun.Ramadoss@...rochip.com>
To: <olteanv@...il.com>, <UNGLinuxDriver@...rochip.com>,
<vivien.didelot@...il.com>, <andrew@...n.ch>,
<f.fainelli@...il.com>, <kuba@...nel.org>, <edumazet@...gle.com>,
<pabeni@...hat.com>, <o.rempel@...gutronix.de>,
<Woojung.Huh@...rochip.com>, <davem@...emloft.net>
CC: <linux-kernel@...r.kernel.org>, <netdev@...r.kernel.org>,
<kernel@...gutronix.de>
Subject: Re: [PATCH net-next v1 1/1] net: dsa: microchip: ksz8: add MTU
configuration support
Hi Oleksij,
On Thu, 2022-11-03 at 10:13 +0100, Oleksij Rempel wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you
> know the content is safe
>
> Make MTU configurable on KSZ87xx and KSZ88xx series of switches.
>
> Before this patch, pre-configured behavior was different on different
> switch series, due to opposite meaning of the same bit:
> - KSZ87xx: Reg 4, Bit 1 - if 1, max frame size is 1532; if 0 - 1514
> - KSZ88xx: Reg 4, Bit 1 - if 1, max frame size is 1514; if 0 - 1532
>
> Since the code was telling "... SW_LEGAL_PACKET_DISABLE, true)", I
> assume, the idea was to set max frame size to 1532.
>
> With this patch, by setting MTU size 1500, both switch series will be
> configured to the 1532 frame limit.
>
> This patch was tested on KSZ8873.
>
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
> drivers/net/dsa/microchip/ksz8.h | 2 +
> drivers/net/dsa/microchip/ksz8795.c | 74
> ++++++++++++++++++++++++-
> drivers/net/dsa/microchip/ksz8795_reg.h | 9 +++
> drivers/net/dsa/microchip/ksz_common.c | 2 +
> 4 files changed, 85 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/dsa/microchip/ksz8.h
> b/drivers/net/dsa/microchip/ksz8.h
> index 8582b4b67d98..027b92f5fa73 100644
> --- a/drivers/net/dsa/microchip/ksz8.h
> +++ b/drivers/net/dsa/microchip/ksz8.h
> @@ -57,5 +57,7 @@ int ksz8_reset_switch(struct ksz_device *dev);
> int ksz8_switch_detect(struct ksz_device *dev);
> int ksz8_switch_init(struct ksz_device *dev);
> void ksz8_switch_exit(struct ksz_device *dev);
> +int ksz8_change_mtu(struct ksz_device *dev, int port, int mtu);
> +int ksz8_max_mtu(struct ksz_device *dev, int port);
>
> #endif
> diff --git a/drivers/net/dsa/microchip/ksz8795.c
> b/drivers/net/dsa/microchip/ksz8795.c
> index bd3b133e7085..fd2539aabb2c 100644
> --- a/drivers/net/dsa/microchip/ksz8795.c
> +++ b/drivers/net/dsa/microchip/ksz8795.c
> @@ -76,6 +76,78 @@ int ksz8_reset_switch(struct ksz_device *dev)
> return 0;
> }
>
> +static int ksz8863_change_mtu(struct ksz_device *dev, int port, int
> max_frame)
> +{
> + u8 ctrl2 = 0;
> +
> + if (max_frame <= KSZ8863_LEGAL_PACKET_SIZE)
> + ctrl2 |= KSZ8863_LEGAL_PACKET_ENABLE;
> + else if (max_frame > KSZ8863_NORMAL_PACKET_SIZE)
> + ctrl2 |= KSZ8863_HUGE_PACKET_ENABLE;
> +
> + return regmap_update_bits(dev->regmap[0], REG_SW_CTRL_2,
> + KSZ8863_LEGAL_PACKET_ENABLE
> + | KSZ8863_HUGE_PACKET_ENABLE,
> ctrl2);
> +}
Suggestion:
regmap_update_bits, can you create a macro like ksz_rmw8 similar to
what we have ksz_prmw8 in ksz_common.h. So that it can used across the
ksz and lan937x switches.
> +
> +static int ksz8795_change_mtu(struct ksz_device *dev, int port, int
> max_frame)
> +{
> + u8 ctrl1 = 0, ctrl2 = 0;
> + int ret;
> +
> + if (max_frame > KSZ8863_LEGAL_PACKET_SIZE)
> + ctrl2 |= SW_LEGAL_PACKET_DISABLE;
> + else if (max_frame > KSZ8863_NORMAL_PACKET_SIZE)
> + ctrl1 |= SW_HUGE_PACKET;
> +
> + ret = regmap_update_bits(dev->regmap[0], REG_SW_CTRL_1,
> + SW_HUGE_PACKET, ctrl1);
> + if (ret)
> + return ret;
> +
> + return regmap_update_bits(dev->regmap[0], REG_SW_CTRL_2,
> + SW_LEGAL_PACKET_DISABLE, ctrl2);
> +}
> +
> +int ksz8_change_mtu(struct ksz_device *dev, int port, int mtu)
> +{
> + u16 frame_size, max_frame = 0;
> + int i;
> +
> + frame_size = mtu + VLAN_ETH_HLEN + ETH_FCS_LEN;
> +
> + /* Cache the per-port MTU setting */
> + dev->ports[port].max_frame = frame_size;
> +
> + for (i = 0; i < dev->info->port_cnt; i++)
> + max_frame = max(max_frame, dev->ports[i].max_frame);
This port caching snippet is present in ksz9477_change_mtu function
also. It can be moved to ksz_change_mtu and remove it in
ksz9477_change_mtu.
> +
> + switch (dev->chip_id) {
> + case KSZ8795_CHIP_ID:
> + case KSZ8794_CHIP_ID:
> + case KSZ8765_CHIP_ID:
> + return ksz8795_change_mtu(dev, port, max_frame);
> + case KSZ8830_CHIP_ID:
> + return ksz8863_change_mtu(dev, port, max_frame);
> + }
> +
> + return -EOPNOTSUPP;
> +}
> +
> +int ksz8_max_mtu(struct ksz_device *dev, int port)
> +{
> + switch (dev->chip_id) {
> + case KSZ8795_CHIP_ID:
> + case KSZ8794_CHIP_ID:
> + case KSZ8765_CHIP_ID:
> + return KSZ8795_HUGE_PACKET_SIZE - VLAN_ETH_HLEN -
> ETH_FCS_LEN;
> + case KSZ8830_CHIP_ID:
> + return KSZ8863_HUGE_PACKET_SIZE - VLAN_ETH_HLEN -
> ETH_FCS_LEN;
> + }
> +
> + return -EOPNOTSUPP;
> +}
> +
Intially KSZ9477 had the max_mtu which I used for the LAN937x. Since
there is no much thing to do in this function, why can't we move it
ksz_common.c and add chip id for ksz9 and lan937x & remove
ksz9477_max_mtu. It will reduce the max_mtu functioin pointer in
ksz_dev_ops.
>
> diff --git a/drivers/net/dsa/microchip/ksz_common.c
> b/drivers/net/dsa/microchip/ksz_common.c
> index d612181b3226..40fd78951bf8 100644
> --- a/drivers/net/dsa/microchip/ksz_common.c
> +++ b/drivers/net/dsa/microchip/ksz_common.c
> @@ -171,6 +171,8 @@ static const struct ksz_dev_ops ksz8_dev_ops = {
> .reset = ksz8_reset_switch,
> .init = ksz8_switch_init,
> .exit = ksz8_switch_exit,
> + .change_mtu = ksz8_change_mtu,
> + .max_mtu = ksz8_max_mtu,
> };
>
> static void ksz9477_phylink_mac_link_up(struct ksz_device *dev, int
> port,
> -
> 2.30.2
>
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