Subject: Re: [PATCH] net: sfp: add SMBus I2C block support

From: Jakub Kicinski <[email-masked]>
Date: Sun, 4 Jan 2026 08:05:34 -0800

On Sun, 28 Dec 2025 21:33:31 +0000 Jonas Jelonek wrote:
> +static int sfp_smbus_block_write(struct sfp *sfp, bool a2, u8 dev_addr,
> +				 void *buf, size_t len)
> +{
> +	size_t block_size = sfp->i2c_block_size;
> +	union i2c_smbus_data smbus_data;
> +	u8 bus_addr = a2 ? 0x51 : 0x50;
> +	u8 *data = buf;
> +	u8 this_len;
> +	int ret;
> +
> +	while (len) {
> +		this_len = min(len, block_size);
> +
> +		smbus_data.block[0] = this_len;
> +		memcpy(&smbus_data.block[1], data, this_len);
> +		ret = i2c_smbus_xfer(sfp->i2c, bus_addr, 0,
> +				     I2C_SMBUS_WRITE, dev_addr,
> +				     I2C_SMBUS_I2C_BLOCK_DATA, &smbus_data);
> +		if (ret)
> +			return ret;
> +
> +		len -= this_len;
> +		data += this_len;
> +		dev_addr += this_len;
> +	}
> +
> +	return 0;
> +}

AI code review says:

 Should this return the number of bytes written instead of 0?

 The existing sfp_i2c_write() returns the byte count on success, and several
 callers depend on this return value:

 sfp_cotsworks_fixup_check() checks:
    err = sfp_write(sfp, false, SFP_PHYS_ID, &id->base, 3);
    if (err != 3) { ... error path ... }

 sfp_sm_mod_hpower() via sfp_modify_u8() checks:
    if (err != sizeof(u8)) { ... error path ... }

 With this function returning 0 on success, these checks will always fail,
 causing high-power SFP modules to fail initialization with "failed to enable
 high power" errors, and Cotsworks module EEPROM fixups to fail with "Failed
 to rewrite module EEPROM" errors.

Either way, you'll need to repost, net-next was closed when you posted.
-- 
pw-bot: cr