Re: [PATCH net-next] net: sfp: VSOL V2801F / CarlitoxxPro CPGOS03-0490 v2.0 workaround

[Russell King - ARM Linux admin <linux@armlinux.org.uk>]

On Tue, Nov 24, 2020 at 01:20:21AM +0100, Andrew Lunn wrote:
> > @@ -335,10 +336,19 @@ static int sfp_i2c_read(struct sfp *sfp, bool a2, u8 dev_addr, void *buf,
> >  			size_t len)
> >  {
> >  	struct i2c_msg msgs[2];
> > -	u8 bus_addr = a2 ? 0x51 : 0x50;
> > +	size_t block_size;
> >  	size_t this_len;
> > +	u8 bus_addr;
> >  	int ret;
> >  
> > +	if (a2) {
> > +		block_size = 16;
> > +		bus_addr = 0x51;
> 
> Hi Russell, Thomas
> 
> Does this man the diagnostic page can be read 16 bytes at a time, even
> when the other page has to be 1 bytes at a time? That seems rather
> odd. Or is the diagnostic page not implemented in these SFPs?

SFF8472 requires that multibyte values are read using sequential
reads. So we can't use single byte reads to read a multibyte value -
it's just not atomic.

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