On Wed, 2017-02-15 at 10:24 +0200, Yuval Mintz wrote:
> From: Sudarsana Reddy Kalluru <[email protected]>
>
> The patch adds the required qed interfaces for configuring/reading
> the PTP clock on the adapter.
> +/* Read Phy Hardware Clock */
> +static int qed_ptp_hw_read_cc(struct qed_dev *cdev, u64 *phc_cycles)
> +{
> + struct qed_hwfn *p_hwfn = QED_LEADING_HWFN(cdev);
> + struct qed_ptt *p_ptt = p_hwfn->p_ptp_ptt;
> + u32 temp = 0;
> +
> + temp = qed_rd(p_hwfn, p_ptt, NIG_REG_TSGEN_SYNC_TIME_LSB);
> + *phc_cycles = qed_rd(p_hwfn, p_ptt, NIG_REG_TSGEN_SYNC_TIME_MSB);
> + *phc_cycles <<= 32;
> + *phc_cycles |= temp;
> +
> + return 0;
> +}
LSB and MSB being read non atomically, it looks like you could have an
error of (1<<32) cycles here.
(You read LSB value close to 0xFFFFFFFF right before it changes to 0,
while MSB got incremented.)
