From mboxrd@z Thu Jan  1 00:00:00 1970
From: Giuseppe CAVALLARO <peppe.cavallaro@st.com>
Subject: Re: [PATCH (net.git) 2/3] stmmac: fix PTP support for GMAC4
Date: Thu, 27 Oct 2016 12:32:46 +0200
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Cc: netdev <netdev@vger.kernel.org>, <alexandre.torgue@st.com>,
        Richard Cochran <richardcochran@gmail.com>,
        <linux-kernel@vger.kernel.org>, <seraphin.bonnaffe@st.com>
To: Rayagond Kokatanur <rayagond@vayavyalabs.com>
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Hello Rayagond !

On 10/27/2016 12:25 PM, Rayagond Kokatanur wrote:
>> +static int dwmac4_wrback_get_rx_timestamp_status(void *desc, u32 ats)
>> >  {
>> >         struct dma_desc *p = (struct dma_desc *)desc;
>> > +       int ret = -EINVAL;
>> > +
>> > +       /* Get the status from normal w/b descriptor */
>> > +       if (likely(p->des3 & TDES3_RS1V)) {
>> > +               if (likely(p->des1 & RDES1_TIMESTAMP_AVAILABLE)) {
>> > +                       int i = 0;
>> > +
>> > +                       /* Check if timestamp is OK from context descriptor */
>> > +                       do {
>> > +                               ret = dwmac4_rx_check_timestamp(desc);
> Here, "desc" is not pointing to next descriptor (ie context
> descriptor). Driver should check the context descriptor.

you are right and this is done by the caller:  stmmac_get_rx_hwtstamp

Cheers
peppe