netdev - Re: [PATCH net-next] eth: fbnic: Read module EEPROM

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Message-ID: <a7184bd2-2203-465b-b544-4dbea0b9645b@lunn.ch>
Date: Fri, 19 Sep 2025 21:25:44 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Mohsin Bashir <mohsin.bashr@...il.com>
Cc: netdev@...r.kernel.org, alexanderduyck@...com, kuba@...nel.org,
	andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
	gustavoars@...nel.org, horms@...nel.org, jacob.e.keller@...el.com,
	kees@...nel.org, kernel-team@...a.com, lee@...ger.us,
	linux@...linux.org.uk, pabeni@...hat.com, sanman.p211993@...il.com,
	suhui@...china.com, vadim.fedorenko@...ux.dev
Subject: Re: [PATCH net-next] eth: fbnic: Read module EEPROM

On Fri, Sep 19, 2025 at 12:16:24PM -0700, Mohsin Bashir wrote:
> Add support to read module EEPROM for fbnic. Towards this, add required
> support to issue a new command to the firmware and to receive the response
> to the corresponding command.
> 
> Create a local copy of the data in the completion struct before writing to
> ethtool_module_eeprom to avoid writing to data in case it is freed. Given
> that EEPROM pages are small, the overhead of additional copy is
> negligible.
> 
> Signed-off-by: Jakub Kicinski <kuba@...nel.org>
> Signed-off-by: Mohsin Bashir <mohsin.bashr@...il.com>
> ---
>  .../net/ethernet/meta/fbnic/fbnic_ethtool.c   |  66 +++++++++
>  drivers/net/ethernet/meta/fbnic/fbnic_fw.c    | 135 ++++++++++++++++++
>  drivers/net/ethernet/meta/fbnic/fbnic_fw.h    |  22 +++
>  3 files changed, 223 insertions(+)
> 
> diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c b/drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c
> index b4ff98ee2051..f6069cddffa5 100644
> --- a/drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c
> +++ b/drivers/net/ethernet/meta/fbnic/fbnic_ethtool.c
> @@ -1635,6 +1635,71 @@ static void fbnic_get_ts_stats(struct net_device *netdev,
>  	}
>  }
>  
> +static int
> +fbnic_get_module_eeprom_by_page(struct net_device *netdev,
> +				const struct ethtool_module_eeprom *page_data,
> +				struct netlink_ext_ack *extack)
> +{
> +	struct fbnic_net *fbn = netdev_priv(netdev);
> +	struct fbnic_fw_completion *fw_cmpl;
> +	struct fbnic_dev *fbd = fbn->fbd;
> +	int err;
> +
> +	if (page_data->i2c_address != 0x50) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "Invalid i2c address. Only 0x50 is supported");
> +		return -EINVAL;
> +	}
> +
> +	if (page_data->bank != 0) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "Invalid bank. Only 0 is supported");
> +		return -EINVAL;
> +	}
> +
> +	fw_cmpl = __fbnic_fw_alloc_cmpl(FBNIC_TLV_MSG_ID_QSFP_READ_RESP,
> +					page_data->length);
> +	if (!fw_cmpl)
> +		return -ENOMEM;
> +
> +	/* Initialize completion and queue it for FW to process */
> +	fw_cmpl->u.qsfp.length = page_data->length;
> +	fw_cmpl->u.qsfp.offset = page_data->offset;
> +	fw_cmpl->u.qsfp.page = page_data->page;
> +	fw_cmpl->u.qsfp.bank = page_data->bank;
> +
> +	err = fbnic_fw_xmit_qsfp_read_msg(fbd, fw_cmpl, page_data->page,
> +					  page_data->bank, page_data->offset,
> +					  page_data->length);
> +	if (err) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "Failed to transmit EEPROM read request");
> +		goto exit_free;
> +	}

At some point, you are going to hand off control of the I2C bus to
phylink, so it can drive the SFP. I know Alex at least had a plan how
that will work. At that point, will you just throw this away, and let
sfp_get_module_eeprom_by_page() implement this?

	Andrew