netdev - Re: [PATCH net-next v10 4/5] net: rnpgbe: Add basic mbx

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Message-ID: <79CDF6C59BAFF4D1+20250904025752.GC1015062@nic-Precision-5820-Tower>
Date: Thu, 4 Sep 2025 10:57:52 +0800
From: Yibo Dong <dong100@...se.com>
To: Andrew Lunn <andrew@...n.ch>
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, kees@...nel.org,
	gustavoars@...nel.org, rdunlap@...radead.org,
	vadim.fedorenko@...ux.dev, netdev@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH net-next v10 4/5] net: rnpgbe: Add basic mbx_fw support

On Thu, Sep 04, 2025 at 12:45:43AM +0200, Andrew Lunn wrote:
> > +/**
> > + * mucse_mbx_powerup - Echo fw to powerup
> > + * @hw: pointer to the HW structure
> > + * @is_powerup: true for powerup, false for powerdown
> > + *
> > + * mucse_mbx_powerup echo fw to change working frequency
> > + * to normal after received true, and reduce working frequency
> > + * if false.
> > + *
> > + * Return: 0 on success, negative errno on failure
> > + **/
> > +int mucse_mbx_powerup(struct mucse_hw *hw, bool is_powerup)
> > +{
> > +	struct mbx_fw_cmd_req req = {};
> > +	int len;
> > +	int err;
> > +
> > +	build_powerup(&req, is_powerup);
> > +	len = le16_to_cpu(req.datalen);
> > +	mutex_lock(&hw->mbx.lock);
> > +
> > +	if (is_powerup) {
> > +		err = mucse_write_posted_mbx(hw, (u32 *)&req,
> > +					     len);
> > +	} else {
> > +		err = mucse_write_mbx_pf(hw, (u32 *)&req,
> > +					 len);
> > +	}
> 
> It looks odd that this is asymmetric. Why is a different low level
> function used between power up and power down?
> 
> > +int mucse_mbx_reset_hw(struct mucse_hw *hw)
> > +{
> > +	struct mbx_fw_cmd_reply reply = {};
> > +	struct mbx_fw_cmd_req req = {};
> > +
> > +	build_reset_hw_req(&req);
> > +	return mucse_fw_send_cmd_wait(hw, &req, &reply);
> > +}
> 
> And this uses a third low level API different to power up and power
> down?
> 
> 	Andrew
> 

There are 3 APIs, they has some different ....
1. mucse_write_mbx_pf just sends mbx.
/**
 * mucse_write_mbx_pf - Place a message in the mailbox
 * @hw: pointer to the HW structure
 * @msg: the message buffer
 * @size: length of buffer
 *
 */

2. mucse_write_posted_mbx sends mbx and wait fw read out.
/**
 * mucse_write_posted_mbx - Write a message to the mailbox, wait for ack
 * @hw: pointer to the HW structure
 * @msg: the message buffer
 * @size: length of buffer
 */
powerdown is called when driver is removed, nothing to do with fw later,
no need to wait fw's ack.
Of course, it can use mucse_write_posted_mbx to wait when
powerdown if you want me to do it?

3. mucse_fw_send_cmd_wait sends mbx, wait fw read out, and wait for
response.
/**
 * mucse_fw_send_cmd_wait - Send cmd req and wait for response
 * @hw: pointer to the HW structure
 * @req: pointer to the cmd req structure
 * @reply: pointer to the fw reply structure
 */

 Thanks for feedback.