linux-kernel - Re: [PATCH 03/15] net: rnpgbe: Add basic mbx ops support

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Message-ID: <80644ec1-a313-403a-82dd-62eb551442d3@lunn.ch>
Date: Fri, 4 Jul 2025 20:13:19 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Dong Yibo <dong100@...se.com>
Cc: davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
	pabeni@...hat.com, horms@...nel.org, corbet@....net,
	andrew+netdev@...n.ch, 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, netdev@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/15] net: rnpgbe: Add basic mbx ops support

>  #define MBX_FEATURE_WRITE_DELAY BIT(1)
>  	u32 mbx_feature;
>  	/* cm3 <-> pf mbx */
> -	u32 cpu_pf_shm_base;
> -	u32 pf2cpu_mbox_ctrl;
> -	u32 pf2cpu_mbox_mask;
> -	u32 cpu_pf_mbox_mask;
> -	u32 cpu2pf_mbox_vec;
> +	u32 fw_pf_shm_base;
> +	u32 pf2fw_mbox_ctrl;
> +	u32 pf2fw_mbox_mask;
> +	u32 fw_pf_mbox_mask;
> +	u32 fw2pf_mbox_vec;

Why is a patch adding a new feature deleting code?

> +/**
> + * mucse_read_mbx - Reads a message from the mailbox
> + * @hw: Pointer to the HW structure
> + * @msg: The message buffer
> + * @size: Length of buffer
> + * @mbx_id: Id of vf/fw to read
> + *
> + * returns 0 if it successfully read message or else
> + * MUCSE_ERR_MBX.
> + **/
> +s32 mucse_read_mbx(struct mucse_hw *hw, u32 *msg, u16 size,

s32 is an unusual type for linux. Can the mbox actually return
negative amounts of data?

> +/**
> + * mucse_write_mbx - Write a message to the mailbox
> + * @hw: Pointer to the HW structure
> + * @msg: The message buffer
> + * @size: Length of buffer
> + * @mbx_id: Id of vf/fw to write
> + *
> + * returns 0 if it successfully write message or else
> + * MUCSE_ERR_MBX.

Don't invent new error codes. EINVAL would do.

> + **/
> +s32 mucse_write_mbx(struct mucse_hw *hw, u32 *msg, u16 size,
> +		    enum MBX_ID mbx_id)
> +{
> +	struct mucse_mbx_info *mbx = &hw->mbx;
> +	s32 ret_val = 0;
> +
> +	if (size > mbx->size)
> +		ret_val = MUCSE_ERR_MBX;
> +	else if (mbx->ops.write)
> +		ret_val = mbx->ops.write(hw, msg, size, mbx_id);
> +
> +	return ret_val;
> +}
> +static inline void mucse_mbx_inc_pf_ack(struct mucse_hw *hw,
> +					enum MBX_ID mbx_id)

No inline functions in C files. Let the compiler decide.

> +static s32 mucse_poll_for_msg(struct mucse_hw *hw, enum MBX_ID mbx_id)
> +{
> +	struct mucse_mbx_info *mbx = &hw->mbx;
> +	int countdown = mbx->timeout;
> +
> +	if (!countdown || !mbx->ops.check_for_msg)
> +		goto out;
> +
> +	while (countdown && mbx->ops.check_for_msg(hw, mbx_id)) {
> +		countdown--;
> +		if (!countdown)
> +			break;
> +		udelay(mbx->usec_delay);
> +	}
> +out:
> +	return countdown ? 0 : -ETIME;

ETIMEDOUT, not ETIME. Please use iopoll.h, not roll your own.

    Andrew

---
pw-bot: cr