netdev - Re: [PATCH net-next 1/6] net: macb: Define ENST hardware registers for time-aware scheduling

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Message-ID: <1fd25ba2-578c-46f2-acf2-903ae5d9e8bf@tuxon.dev>
Date: Sat, 26 Jul 2025 15:23:37 +0300
From: "claudiu beznea (tuxon)" <claudiu.beznea@...on.dev>
To: Vineeth Karumanchi <vineeth.karumanchi@....com>,
 nicolas.ferre@...rochip.com, andrew+netdev@...n.ch, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com
Cc: git@....com, netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next 1/6] net: macb: Define ENST hardware registers
 for time-aware scheduling

Hi, Vineeth,

On 7/22/25 18:41, Vineeth Karumanchi wrote:
> Add ENST (Enhanced Network Scheduling and Timing) register definitions
> to support IEEE 802.1Qbv time-gated transmission.
> 
> Register architecture:
> - Per-queue timing registers: ENST_START_TIME, ENST_ON_TIME, ENST_OFF_TIME
> - Centralized control of the ENST_CONTROL register for enabling or
>    disabling queue gates.
> - Time intervals programmed in hardware byte units
> - Hardware-level queue scheduling infrastructure.
> 
> Signed-off-by: Vineeth Karumanchi <vineeth.karumanchi@....com>
> ---
>   drivers/net/ethernet/cadence/macb.h | 43 +++++++++++++++++++++++++++++
>   1 file changed, 43 insertions(+)
> 
> diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
> index c9a5c8beb2fa..e456ac65d6c6 100644
> --- a/drivers/net/ethernet/cadence/macb.h
> +++ b/drivers/net/ethernet/cadence/macb.h
> @@ -184,6 +184,13 @@
>   #define GEM_DCFG8		0x029C /* Design Config 8 */
>   #define GEM_DCFG10		0x02A4 /* Design Config 10 */
>   #define GEM_DCFG12		0x02AC /* Design Config 12 */
> +#define GEM_ENST_START_TIME_Q0	0x0800 /* ENST Q0 start time */
> +#define GEM_ENST_START_TIME_Q1	0x0804 /* ENST Q1 start time */
> +#define GEM_ENST_ON_TIME_Q0	0x0820 /* ENST Q0 on time */
> +#define GEM_ENST_ON_TIME_Q1	0x0824 /* ENST Q1 on time */
> +#define GEM_ENST_OFF_TIME_Q0	0x0840 /* ENST Q0 off time */
> +#define GEM_ENST_OFF_TIME_Q1	0x0844 /* ENST Q1 off time */
> +#define GEM_ENST_CONTROL	0x0880 /* ENST control register */
>   #define GEM_USX_CONTROL		0x0A80 /* High speed PCS control register */
>   #define GEM_USX_STATUS		0x0A88 /* High speed PCS status register */
>   
> @@ -221,6 +228,15 @@
>   #define GEM_IDR(hw_q)		(0x0620 + ((hw_q) << 2))
>   #define GEM_IMR(hw_q)		(0x0640 + ((hw_q) << 2))
>   
> +#define GEM_ENST_START_TIME(hw_q)	(0x0800 + ((hw_q) << 2))
> +#define GEM_ENST_ON_TIME(hw_q)		(0x0820 + ((hw_q) << 2))
> +#define GEM_ENST_OFF_TIME(hw_q)		(0x0840 + ((hw_q) << 2))
> +
> +/*  Bitfields in ENST_CONTROL. */
> +#define GEM_ENST_DISABLE_QUEUE(hw_q)	BIT((hw_q) + 16) /* q0 disable is 16'b */
> +#define GEM_ENST_DISABLE_QUEUE_OFFSET	16
> +#define GEM_ENST_ENABLE_QUEUE(hw_q)		BIT(hw_q) /* q0 enable is 0'b */

There is an extra tab here ------------^

> +
>   /* Bitfields in NCR */
>   #define MACB_LB_OFFSET		0 /* reserved */
>   #define MACB_LB_SIZE		1
> @@ -554,6 +570,33 @@
>   #define GEM_HIGH_SPEED_OFFSET			26
>   #define GEM_HIGH_SPEED_SIZE			1
>   
> +/* Bitfields in ENST_START_TIME_Q0, Q1. */
> +#define GEM_START_TIME_SEC_OFFSET		30
> +#define GEM_START_TIME_SEC_SIZE			2
> +#define GEM_START_TIME_NSEC_OFFSET		0
> +#define GEM_START_TIME_NSEC_SIZE		30
> +
> +/* Bitfields in ENST_ON_TIME_Q0, Q1. */
> +#define GEM_ON_TIME_OFFSET			0
> +#define GEM_ON_TIME_SIZE			17
> +
> +/* Bitfields in ENST_OFF_TIME_Q0, Q1. */
> +#define GEM_OFF_TIME_OFFSET			0
> +#define GEM_OFF_TIME_SIZE			17
> +
> +/* Hardware ENST timing registers granularity */
> +#define ENST_TIME_GRANULARITY_NS 8
> +
> +/* Bitfields in ENST_CONTROL. */
> +#define GEM_DISABLE_Q1_OFFSET			17
> +#define GEM_DISABLE_Q1_SIZE			1
> +#define GEM_DISABLE_Q0_OFFSET			16
> +#define GEM_DISABLE_Q0_SIZE			1
> +#define GEM_ENABLE_Q1_OFFSET			1
> +#define GEM_ENABLE_Q1_SIZE			1
> +#define GEM_ENABLE_Q0_OFFSET			0
> +#define GEM_ENABLE_Q0_SIZE			1
> +

Please introduce these defines along with the code that uses it. This way it is 
simpler to follow what is actually used.

Thank you,
Claudiu

>   /* Bitfields in USX_CONTROL. */
>   #define GEM_USX_CTRL_SPEED_OFFSET		14
>   #define GEM_USX_CTRL_SPEED_SIZE			3