RE: [PATCH net-next v3 2/2] net: ethtool: Add support for writing firmware blocks using EPL payload

[Danielle Ratson]

> From: Simon Horman <horms@xxxxxxxxxx>
> Sent: Monday, 30 September 2024 19:42
> To: Danielle Ratson <danieller@xxxxxxxxxx>
> Cc: netdev@xxxxxxxxxxxxxxx; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx;
> kuba@xxxxxxxxxx; pabeni@xxxxxxxxxx; yuehaibing@xxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx; Petr Machata <petrm@xxxxxxxxxx>
> Subject: Re: [PATCH net-next v3 2/2] net: ethtool: Add support for writing
> firmware blocks using EPL payload
> 
> On Mon, Sep 30, 2024 at 11:46:37AM +0300, Danielle Ratson wrote:
> > In the CMIS specification for pluggable modules, LPL (Low-Priority
> > Payload) and EPL (Extended Payload Length) are two types of data
> > payloads used for managing various functions and features of the module.
> >
> > EPL payloads are used for more complex and extensive management
> > functions that require a larger amount of data, so writing firmware
> > blocks using EPL is much more efficient.
> >
> > Currently, only LPL payload is supported for writing firmware blocks
> > to the module.
> >
> > Add support for writing firmware block using EPL payload, both to
> > support modules that supports only EPL write mechanism, and to
> > optimize the flashing process of modules that support LPL and EPL.
> >
> > Signed-off-by: Danielle Ratson <danieller@xxxxxxxxxx>
> > Reviewed-by: Petr Machata <petrm@xxxxxxxxxx>
> > Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
> 
> ...
> 
> > @@ -556,6 +563,49 @@ __ethtool_cmis_cdb_execute_cmd(struct
> net_device *dev,
> >  	return err;
> >  }
> >
> > +#define CMIS_CDB_EPL_PAGE_START			0xA0
> > +#define CMIS_CDB_EPL_PAGE_END			0xAF
> > +#define CMIS_CDB_EPL_FW_BLOCK_OFFSET_START	128
> > +#define CMIS_CDB_EPL_FW_BLOCK_OFFSET_END	255
> > +
> > +static int
> > +ethtool_cmis_cdb_execute_epl_cmd(struct net_device *dev,
> > +				 struct ethtool_cmis_cdb_cmd_args *args,
> > +				 struct ethtool_module_eeprom *page_data) {
> > +	u16 epl_len = be16_to_cpu(args->req.epl_len);
> > +	u32 bytes_written;
> > +	u8 page;
> > +	int err;
> > +
> > +	for (page = CMIS_CDB_EPL_PAGE_START;
> > +	     page <= CMIS_CDB_EPL_PAGE_END && bytes_written < epl_len;
> > +page++) {
> 
> bytes_written does not seem to be initialised here for the first iteration of the
> loop.
> 
> Flagged by W=1 builds with clang-18.

You are right, I mistakenly sent the wrong version. Will send the fixed one.
Thanks.

> 
> > +		u16 offset = CMIS_CDB_EPL_FW_BLOCK_OFFSET_START;
> > +
> > +		while (offset <= CMIS_CDB_EPL_FW_BLOCK_OFFSET_END &&
> > +		       bytes_written < epl_len) {
> > +			u32 bytes_left = epl_len - bytes_written;
> > +			u16 space_left, bytes_to_write;
> > +
> > +			space_left = CMIS_CDB_EPL_FW_BLOCK_OFFSET_END
> - offset + 1;
> > +			bytes_to_write = min_t(u16, bytes_left,
> > +					       min_t(u16, space_left,
> > +						     args->read_write_len_ext));
> > +
> > +			err = __ethtool_cmis_cdb_execute_cmd(dev,
> page_data,
> > +							     page, offset,
> > +							     bytes_to_write,
> > +							     args->req.epl +
> bytes_written);
> > +			if (err < 0)
> > +				return err;
> > +
> > +			offset += bytes_to_write;
> > +			bytes_written += bytes_to_write;
> > +		}
> > +	}
> > +	return 0;
> > +}
> > +
> >  static u8 cmis_cdb_calc_checksum(const void *data, size_t size)  {
> >  	const u8 *bytes = (const u8 *)data;
> 
> ...
> 
> --
> pw-bot: changes-requested