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Date:   Thu, 17 Mar 2022 21:52:46 +0200
From:   Vladimir Oltean <olteanv@gmail.com>
To:     Oleksij Rempel <o.rempel@pengutronix.de>
Cc:     Woojung Huh <woojung.huh@microchip.com>,
        UNGLinuxDriver@microchip.com, Andrew Lunn <andrew@lunn.ch>,
        Florian Fainelli <f.fainelli@gmail.com>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>, kernel@pengutronix.de,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v1 1/1] net: dsa: microchip: ksz8795: handle eee
 specif erratum
Message-ID: <20220317195246.jy43gwrnao4drljp@skbuf>
References: <20220316125529.1489045-1-o.rempel@pengutronix.de>
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In-Reply-To: <20220316125529.1489045-1-o.rempel@pengutronix.de>
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On Wed, Mar 16, 2022 at 01:55:29PM +0100, Oleksij Rempel wrote:
> According to erratum described in DS80000687C[1]: "Module 2: Link drops with
> some EEE link partners.", we need to "Disable the EEE next page
> exchange in EEE Global Register 2"
> 
> 1 - https://ww1.microchip.com/downloads/en/DeviceDoc/KSZ87xx-Errata-DS80000687C.pdf
> 
> Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
> ---

I don't possess KSZ8 switches, but there doesn't look anything wrong to
me with this patch, so:

Reviewed-by: Vladimir Oltean <olteanv@gmail.com>

>  drivers/net/dsa/microchip/ksz8.h        |  1 +
>  drivers/net/dsa/microchip/ksz8795.c     | 45 ++++++++++++++++++++++++-
>  drivers/net/dsa/microchip/ksz8795_reg.h |  4 +++
>  drivers/net/dsa/microchip/ksz_common.h  |  1 +
>  4 files changed, 50 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/microchip/ksz8.h b/drivers/net/dsa/microchip/ksz8.h
> index 9d611895d3cf..03da369675c6 100644
> --- a/drivers/net/dsa/microchip/ksz8.h
> +++ b/drivers/net/dsa/microchip/ksz8.h
> @@ -16,6 +16,7 @@ enum ksz_regs {
>  	REG_IND_DATA_HI,
>  	REG_IND_DATA_LO,
>  	REG_IND_MIB_CHECK,
> +	REG_IND_BYTE,
>  	P_FORCE_CTRL,
>  	P_LINK_STATUS,
>  	P_LOCAL_CTRL,
> diff --git a/drivers/net/dsa/microchip/ksz8795.c b/drivers/net/dsa/microchip/ksz8795.c
> index 5dc9899bc0a6..6f9cdd5204fb 100644
> --- a/drivers/net/dsa/microchip/ksz8795.c
> +++ b/drivers/net/dsa/microchip/ksz8795.c
> @@ -33,6 +33,7 @@ static const u8 ksz8795_regs[] = {
>  	[REG_IND_DATA_HI]		= 0x71,
>  	[REG_IND_DATA_LO]		= 0x75,
>  	[REG_IND_MIB_CHECK]		= 0x74,
> +	[REG_IND_BYTE]			= 0xA0,
>  	[P_FORCE_CTRL]			= 0x0C,
>  	[P_LINK_STATUS]			= 0x0E,
>  	[P_LOCAL_CTRL]			= 0x07,
> @@ -222,6 +223,25 @@ static void ksz_port_cfg(struct ksz_device *dev, int port, int offset, u8 bits,
>  			   bits, set ? bits : 0);
>  }
>  
> +static int ksz8_ind_write8(struct ksz_device *dev, u8 table, u16 addr, u8 data)
> +{
> +	struct ksz8 *ksz8 = dev->priv;
> +	const u8 *regs = ksz8->regs;
> +	u16 ctrl_addr;
> +	int ret = 0;
> +
> +	mutex_lock(&dev->alu_mutex);
> +
> +	ctrl_addr = IND_ACC_TABLE(table) | addr;
> +	ret = ksz_write8(dev, regs[REG_IND_BYTE], data);
> +	if (!ret)
> +		ret = ksz_write16(dev, regs[REG_IND_CTRL_0], ctrl_addr);
> +
> +	mutex_unlock(&dev->alu_mutex);
> +
> +	return ret;
> +}
> +
>  static int ksz8_reset_switch(struct ksz_device *dev)
>  {
>  	if (ksz_is_ksz88x3(dev)) {
> @@ -1391,6 +1411,23 @@ static void ksz8_config_cpu_port(struct dsa_switch *ds)
>  	}
>  }
>  
> +static int ksz8_handle_global_errata(struct dsa_switch *ds)
> +{
> +	struct ksz_device *dev = ds->priv;
> +	int ret = 0;
> +
> +	/* KSZ87xx Errata DS80000687C.
> +	 * Module 2: Link drops with some EEE link partners.
> +	 *   An issue with the EEE next page exchange between the
> +	 *   KSZ879x/KSZ877x/KSZ876x and some EEE link partners may result in
> +	 *   the link dropping.
> +	 */
> +	if (dev->ksz87xx_eee_link_erratum)
> +		ret = ksz8_ind_write8(dev, TABLE_EEE, REG_IND_EEE_GLOB2_HI, 0);
> +
> +	return ret;
> +}
> +
>  static int ksz8_setup(struct dsa_switch *ds)
>  {
>  	struct ksz_device *dev = ds->priv;
> @@ -1458,7 +1495,7 @@ static int ksz8_setup(struct dsa_switch *ds)
>  
>  	ds->configure_vlan_while_not_filtering = false;
>  
> -	return 0;
> +	return ksz8_handle_global_errata(ds);
>  }
>  
>  static void ksz8_get_caps(struct dsa_switch *ds, int port,
> @@ -1575,6 +1612,7 @@ struct ksz_chip_data {
>  	int num_statics;
>  	int cpu_ports;
>  	int port_cnt;
> +	bool ksz87xx_eee_link_erratum;
>  };
>  
>  static const struct ksz_chip_data ksz8_switch_chips[] = {
> @@ -1586,6 +1624,7 @@ static const struct ksz_chip_data ksz8_switch_chips[] = {
>  		.num_statics = 8,
>  		.cpu_ports = 0x10,	/* can be configured as cpu port */
>  		.port_cnt = 5,		/* total cpu and user ports */
> +		.ksz87xx_eee_link_erratum = true,
>  	},
>  	{
>  		/*
> @@ -1609,6 +1648,7 @@ static const struct ksz_chip_data ksz8_switch_chips[] = {
>  		.num_statics = 8,
>  		.cpu_ports = 0x10,	/* can be configured as cpu port */
>  		.port_cnt = 4,		/* total cpu and user ports */
> +		.ksz87xx_eee_link_erratum = true,
>  	},
>  	{
>  		.chip_id = 0x8765,
> @@ -1618,6 +1658,7 @@ static const struct ksz_chip_data ksz8_switch_chips[] = {
>  		.num_statics = 8,
>  		.cpu_ports = 0x10,	/* can be configured as cpu port */
>  		.port_cnt = 5,		/* total cpu and user ports */
> +		.ksz87xx_eee_link_erratum = true,
>  	},
>  	{
>  		.chip_id = 0x8830,
> @@ -1652,6 +1693,8 @@ static int ksz8_switch_init(struct ksz_device *dev)
>  			dev->host_mask = chip->cpu_ports;
>  			dev->port_mask = (BIT(dev->phy_port_cnt) - 1) |
>  					 chip->cpu_ports;
> +			dev->ksz87xx_eee_link_erratum =
> +				chip->ksz87xx_eee_link_erratum;
>  			break;
>  		}
>  	}
> diff --git a/drivers/net/dsa/microchip/ksz8795_reg.h b/drivers/net/dsa/microchip/ksz8795_reg.h
> index 6b40bc25f7ff..d74defcd86b4 100644
> --- a/drivers/net/dsa/microchip/ksz8795_reg.h
> +++ b/drivers/net/dsa/microchip/ksz8795_reg.h
> @@ -812,6 +812,10 @@
>  
>  #define IND_ACC_TABLE(table)		((table) << 8)
>  
> +/* */
> +#define REG_IND_EEE_GLOB2_LO		0x34
> +#define REG_IND_EEE_GLOB2_HI		0x35
> +
>  /* Driver set switch broadcast storm protection at 10% rate. */
>  #define BROADCAST_STORM_PROT_RATE	10
>  
> diff --git a/drivers/net/dsa/microchip/ksz_common.h b/drivers/net/dsa/microchip/ksz_common.h
> index fa39ee73cbd2..485d4a948c38 100644
> --- a/drivers/net/dsa/microchip/ksz_common.h
> +++ b/drivers/net/dsa/microchip/ksz_common.h
> @@ -77,6 +77,7 @@ struct ksz_device {
>  	phy_interface_t compat_interface;
>  	u32 regs_size;
>  	bool phy_errata_9477;
> +	bool ksz87xx_eee_link_erratum;
>  	bool synclko_125;
>  	bool synclko_disable;
>  
> -- 
> 2.30.2
>