linux-kernel - RE: [RFC PATCH net-next 9/9] ethtool: Add ability to flash transceiver modules' firmware

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Date: Wed, 24 Jan 2024 13:11:22 +0000
From: Danielle Ratson <danieller@...dia.com>
To: Russell King <linux@...linux.org.uk>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, "davem@...emloft.net"
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	<mlxsw@...dia.com>, Petr Machata <petrm@...dia.com>, Ido Schimmel
	<idosch@...dia.com>
Subject: RE: [RFC PATCH net-next 9/9] ethtool: Add ability to flash
 transceiver modules' firmware

> > +#define MODULE_EEPROM_PAGE	0
> > +#define MODULE_EEPROM_OFFSET	0
> > +#define MODULE_EEPROM_LENGTH	1
> > +#define MODULE_EEPROM_I2C_ADDR	0x50
> > +
> > +static int module_flash_fw_work_init(struct ethtool_module_fw_flash
> *module_fw,
> > +				     struct net_device *dev,
> > +				     struct netlink_ext_ack *extack) {
> > +	const struct ethtool_ops *ops = dev->ethtool_ops;
> > +	struct ethtool_module_eeprom page_data = {};
> > +	struct module_sff8024_id_rpl *rpl;
> > +	int err;
> > +
> > +	/* Fetch the SFF-8024 Identifier Value. For all supported standards, it
> > +	 * is located at I2C address 0x50, byte 0. See section 4.1 in SFF-8024,
> > +	 * revision 4.9.
> > +	 */
> > +	page_data.page = MODULE_EEPROM_PAGE;
> > +	page_data.offset = MODULE_EEPROM_OFFSET;
> > +	page_data.length = MODULE_EEPROM_LENGTH;
> > +	page_data.i2c_address = MODULE_EEPROM_I2C_ADDR;
> 
> Please use better names - these aren't any better than using integers.
> 
> Maybe use SFP_PHYS_ID for the offset?
> 
> > +	page_data.data = kmalloc(page_data.length, GFP_KERNEL);
> > +	if (!page_data.data)
> > +		return -ENOMEM;
> > +
> > +	err = ops->get_module_eeprom_by_page(dev, &page_data, extack);
> > +	if (err < 0)
> > +		goto out;
> > +
> > +	rpl = (struct module_sff8024_id_rpl *)page_data.data;
> 
> What purpose does this structure of a single byte serve? To me, it just
> obfuscates the code.
> 
> 	u8 phys_id;
> 
> 	...
> 	page_data.offset = SFP_PHYS_ID;
> 	page_data.length = sizeof(phys_id);
> 	page_data.data = &phys_id;
> 	...
> 	switch (phys_id) {
> 
> will work just as well, and be more explicit about what's actually going on
> here. It doesn't mean that I have to understand what this new
> module_sff8024_id_rpl structure is. I can see that we're just getting one byte
> which is the module physical ID.
> 
> You also then don't need to care about kfree()ing one byte of data structure.

OK, will change, thanks!

> 
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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