linux-kernel - Re: [PATCH v4 3/5] net: rnpgbe: Add basic mbx ops support

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Message-ID: <edf9be27-fdbf-44c9-8ce8-86ba25147f02@lunn.ch>
Date: Fri, 15 Aug 2025 04:29:28 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Dong Yibo <dong100@...se.com>
Cc: andrew+netdev@...n.ch, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
	corbet@....net, gur.stavi@...wei.com, maddy@...ux.ibm.com,
	mpe@...erman.id.au, danishanwar@...com, lee@...ger.us,
	gongfan1@...wei.com, lorenzo@...nel.org, geert+renesas@...der.be,
	Parthiban.Veerasooran@...rochip.com, lukas.bulwahn@...hat.com,
	alexanderduyck@...com, richardcochran@...il.com,
	netdev@...r.kernel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 3/5] net: rnpgbe: Add basic mbx ops support

> +#define MUCSE_MAILBOX_WORDS 14
> +#define MUCSE_FW_MAILBOX_WORDS MUCSE_MAILBOX_WORDS
> +#define FW_PF_SHM(mbx) ((mbx)->fw_pf_shm_base)
> +#define FW2PF_COUNTER(mbx) (FW_PF_SHM(mbx) + 0)
> +#define PF2FW_COUNTER(mbx) (FW_PF_SHM(mbx) + 4)
> +#define FW_PF_SHM_DATA(mbx) (FW_PF_SHM(mbx) + 8)

There seems to be quite a bit of obfuscation here. Why is both
MUCSE_MAILBOX_WORDS and MUCSE_FW_MAILBOX_WORDS needed?

Why not

#define FW2PF_COUNTER(mbx) (mbx->fw_pf_shm_base + 0)

Or even better

#define MBX_FW2PF_COUNTER	0
#define MBX_W2PF_COUNTER	4
#define MBX_FW_PF_SHM_DATA	8

static u32 mbx_rd32(struct mbx *mbx, int reg) {

       return readl(mbx->hw->hw_addr + reg);
}

	u32 val = mbx_rd32(mbx, MBX_FW2PF_COUNTER);

Look at what other drivers do. They are much more likely to define a
set of offset from the base address, and let the read/write helper do
the addition to the base.

	Andrew