netdev - Re: [PATCH v7 net-next 5/8] net: ethernet: ti: am65-cpsw: add mqprio qdisc offload in channel mode

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Date: Mon, 4 Dec 2023 15:48:30 +0200
From: Vladimir Oltean <vladimir.oltean@....com>
To: Roger Quadros <rogerq@...nel.org>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, s-vadapalli@...com, r-gunasekaran@...com,
	vigneshr@...com, srk@...com, horms@...nel.org, p-varis@...com,
	netdev@...r.kernel.org
Subject: Re: [PATCH v7 net-next 5/8] net: ethernet: ti: am65-cpsw: add mqprio
 qdisc offload in channel mode

On Fri, Dec 01, 2023 at 03:57:59PM +0200, Roger Quadros wrote:
> diff --git a/drivers/net/ethernet/ti/am65-cpsw-qos.c b/drivers/net/ethernet/ti/am65-cpsw-qos.c
> index 49ae9d1cd948..2733bac55bfa 100644
> --- a/drivers/net/ethernet/ti/am65-cpsw-qos.c
> +++ b/drivers/net/ethernet/ti/am65-cpsw-qos.c
> @@ -15,6 +15,8 @@
>  #include "am65-cpts.h"
>  #include "cpsw_ale.h"
>  
> +#define TO_MBPS(x)	((x) * 8 / 1000000)

Can be rewritten as ((x) * BITS_PER_BYTE / MEGA)

and further as ((x) / BYTES_PER_MBIT).

Also, I wonder if it wouldn't be better to do a DIV_ROUND_UP(x, BYTES_PER_MBIT)
instead. When user space requests a certain bandwidth, it expects to get it.
If the hardware is not fine grained enough, it should prefer giving it slightly
more rather than slightly less.