[dpdk-dev] [PATCH v5 06/10] net/ixgbe: implement power management API

[Wang, Haiyue]

Hi Liang,

> -----Original Message-----
> From: Burakov, Anatoly <anatoly.burakov at intel.com>
> Sent: Saturday, October 10, 2020 00:02
> To: dev at dpdk.org
> Cc: Ma, Liang J <liang.j.ma at intel.com>; Guo, Jia <jia.guo at intel.com>; Wang, Haiyue
> <haiyue.wang at intel.com>; Hunt, David <david.hunt at intel.com>; Ananyev, Konstantin
> <konstantin.ananyev at intel.com>; jerinjacobk at gmail.com; Richardson, Bruce <bruce.richardson at intel.com>;
> thomas at monjalon.net; McDaniel, Timothy <timothy.mcdaniel at intel.com>; Eads, Gage <gage.eads at intel.com>;
> Macnamara, Chris <chris.macnamara at intel.com>
> Subject: [PATCH v5 06/10] net/ixgbe: implement power management API
> 
> From: Liang Ma <liang.j.ma at intel.com>
> 
> Implement support for the power management API by implementing a
> `get_wake_addr` function that will return an address of an RX ring's
> status bit.
> 
> Signed-off-by: Anatoly Burakov <anatoly.burakov at intel.com>
> Signed-off-by: Liang Ma <liang.j.ma at intel.com>
> ---
>  drivers/net/ixgbe/ixgbe_ethdev.c |  1 +
>  drivers/net/ixgbe/ixgbe_rxtx.c   | 22 ++++++++++++++++++++++
>  drivers/net/ixgbe/ixgbe_rxtx.h   |  2 ++
>  3 files changed, 25 insertions(+)
> 


> 
> +int ixgbe_get_wake_addr(void *rx_queue, volatile void **tail_desc_addr,
> +		uint64_t *expected, uint64_t *mask)
> +{
> +	volatile union ixgbe_adv_rx_desc *rxdp;
> +	struct ixgbe_rx_queue *rxq = rx_queue;
> +	uint16_t desc;
> +
> +	desc = rxq->rx_tail;
> +	rxdp = &rxq->rx_ring[desc];
> +	/* watch for changes in status bit */
> +	*tail_desc_addr = &rxdp->wb.upper.status_error;
> +
> +	/*
> +	 * we expect the DD bit to be set to 1 if this descriptor was already
> +	 * written to.
> +	 */
> +	*expected = rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD);
> +	*mask = rte_cpu_to_le_32(IXGBE_RXDADV_STAT_DD);
> +

Seems have one issue about the byte endian:
Like for BIG endian:
         *expected = rte_bswap32(IXGBE_RXDADV_STAT_DD)
             !=
         *expected = rte_bswap64(IXGBE_RXDADV_STAT_DD)

And in API 'rte_power_monitor', use uint64_t type to access the wake up
data:

static inline void rte_power_monitor(const volatile void *p,
		const uint64_t expected_value, const uint64_t value_mask,
		const uint64_t tsc_timestamp)
{
	if (value_mask) {
			const uint64_t cur_value = *(const volatile uint64_t *)p;
			const uint64_t masked = cur_value & value_mask;
			/* if the masked value is already matching, abort */
			if (masked == expected_value)
				return;
		}


So that we need the wake up address type like 16/32/64b ?

> --
> 2.17.1