linux-kernel - Re: [PATCH net-next v7 4/5] net: rnpgbe: Add basic mbx

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Message-ID: <f375e4bf-9b0b-49ca-b83d-addeb49384b8@lunn.ch>
Date: Sat, 23 Aug 2025 17:17:45 +0200
From: Andrew Lunn <andrew@...n.ch>
To: Yibo Dong <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, kees@...nel.org,
	gustavoars@...nel.org, netdev@...r.kernel.org,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-hardening@...r.kernel.org
Subject: Re: [PATCH net-next v7 4/5] net: rnpgbe: Add basic mbx_fw support

On Sat, Aug 23, 2025 at 09:58:24AM +0800, Yibo Dong wrote:
> On Fri, Aug 22, 2025 at 04:43:16PM +0200, Andrew Lunn wrote:
> > > +/**
> > > + * mucse_mbx_get_capability - Get hw abilities from fw
> > > + * @hw: pointer to the HW structure
> > > + *
> > > + * mucse_mbx_get_capability tries to get capabities from
> > > + * hw. Many retrys will do if it is failed.
> > > + *
> > > + * @return: 0 on success, negative on failure
> > > + **/
> > > +int mucse_mbx_get_capability(struct mucse_hw *hw)
> > > +{
> > > +	struct hw_abilities ability = {};
> > > +	int try_cnt = 3;
> > > +	int err = -EIO;
> > > +
> > > +	while (try_cnt--) {
> > > +		err = mucse_fw_get_capability(hw, &ability);
> > > +		if (err)
> > > +			continue;
> > > +		hw->pfvfnum = le16_to_cpu(ability.pfnum) & GENMASK_U16(7, 0);
> > > +		return 0;
> > > +	}
> > > +	return err;
> > > +}
> > 
> > Please could you add an explanation why it would fail? Is this to do
> > with getting the driver and firmware in sync? Maybe you should make
> > this explicit, add a function mucse_mbx_sync() with a comment that
> > this is used once during probe to synchronise communication with the
> > firmware. You can then remove this loop here.
> 
> It is just get some fw capability(or info such as fw version).
> It is failed maybe:
> 1. -EIO: return by mucse_obtain_mbx_lock_pf. The function tries to get
> pf-fw lock(in chip register, not driver), failed when fw hold the lock.

If it cannot get the lock, isn't that fatal? You cannot do anything
without the lock.

> 2. -ETIMEDOUT: return by mucse_poll_for_xx. Failed when timeout.
> 3. -ETIMEDOUT: return by mucse_fw_send_cmd_wait. Failed when wait
> response timeout.

If its dead, its dead. Why would it suddenly start responding?

> 4. -EIO: return by mucse_fw_send_cmd_wait. Failed when error_code in
> response.

Which should be fatal. No retries necessary.

> 5. err return by mutex_lock_interruptible.

So you want the user to have to ^C three times?

And is mucse_mbx_get_capability() special, or will all interactions
with the firmware have three retries?

	Andrew