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Date:   Wed, 1 Jun 2022 15:10:11 -0700
From:   Ira Weiny <ira.weiny@intel.com>
To:     Alison Schofield <alison.schofield@intel.com>
Cc:     "Williams, Dan J" <dan.j.williams@intel.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        "Verma, Vishal L" <vishal.l.verma@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        Ben Widawsky <ben@bwidawsk.net>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>
Subject: Re: [PATCH V9 7/9] cxl/port: Introduce cxl_cdat_valid()
Message-ID: <Ypfjw/5xiKZKWWNu@iweiny-desk3>
References: <20220531152632.1397976-1-ira.weiny@intel.com>
 <20220531152632.1397976-8-ira.weiny@intel.com>
 <20220531172146.GB1457068@alison-desk>
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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@intel.com>
> > 
> > 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