Re: [PATCH V9 7/9] cxl/port: Introduce cxl_cdat_valid()

[Ira Weiny]

On Tue, May 31, 2022 at 10:21:46AM -0700, Alison Schofield wrote:
> On Tue, May 31, 2022 at 08:26:30AM -0700, Ira Weiny wrote:
> > From: Ira Weiny <ira.weiny@xxxxxxxxx>
> > 
> > The CDAT data is protected by a checksum and should be the proper
> > length.
> > 
> > Introduce cxl_cdat_valid() to validate the data.  While at it check and
> > store the sequence number.
> > 
> Store it for ?

To see if a subsequent read shows new data.

> 
> >  
> > +static bool cxl_cdat_valid(struct device *dev, struct cxl_cdat *cdat)
> > +{
> 
> snip
> 
> > +
> > +	seq = FIELD_GET(CDAT_HEADER_DW3_SEQUENCE, table[3]);
> > +	/* Store the sequence for now. */
> > +	if (cdat->seq != seq) {
> > +		dev_info(dev, "CDAT seq change %x -> %x\n", cdat->seq, seq);
> > +		cdat->seq = seq;
> > +	}
> > +
> 
> Wondering when does/will this sequence number come into play?
>

Not until we start reacting to changes in CDAT.

Ira