S32K中的主题 Re: GMAC MTL RXQ_Debug PRXQ read fails

GMAC MTL RXQ_Debug PRXQ read fails

oliver777777 — Mon, 03 Mar 2025 19:06:40 GMT

Hi,

I have ethernet traffic running into GMAC 0 thats functioning properly but I want to periodically read out the packet count of the RXQs in the MTL.

I'm reading off the PRXQ field every 1ms in the MTL_RXQ0_DEBUG, 1, and 2 registers but I'm only getting 0s suggesting that there is never a packet in the RXQ. I've attempted to read across all 3 queues without success. It seems I can read the overflow counter properly, as when I pause GDB the overflow counter will fill up.

I read it through a direct hardware access to the registers:

#define GMAC_MTL_RXQ_GET(x) \
(uint32_t)(((x)&GMAC_MTL_RXQ0_DEBUG_RXQSTS_MASK) >> GMAC_MTL_RXQ0_DEBUG_RXQSTS_SHIFT)

Am I missing something in how the MTL_RXQ_DEBUG register works? Is there a better solution to monitor the DMA/MTL fill status (eth bus load)?

Re: GMAC MTL RXQ_Debug PRXQ read fails

oliver777777 — Mon, 03 Mar 2025 19:40:21 GMT

As a followup: do the corresponding fields in MTL_DBG_CTL have to set correctly to be able to access MTL_RXQ0_DEBUG registers or are they decoupled?

Re: GMAC MTL RXQ_Debug PRXQ read fails

PetrS — Tue, 04 Mar 2025 12:22:59 GMT

Hi oliver,

let me check this RX queue question with Apps team.
Anyway how did you really read MTL_RXQ0_DEBUG register, as this macro just returns RXQSTS field content from given x value?
Maybe module DMA is reading out the queue meanwhile, so you read queue as empty.

What about to simply use MAC Management Counters, which store the statistics about the received and transmitted packets in registers; see more in chapter 76.11 MAC Management Counters of the Reference Manual.

BR, Petr