netdev - Re: [PATCH net v2] net: mdio: aspeed: Add dummy read for fire control

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Message-ID: <d28177c9152408d77840992f2b76efe3cb675b7a.camel@codeconstruct.com.au>
Date: Wed, 20 Nov 2024 15:13:11 +1030
From: Andrew Jeffery <andrew@...econstruct.com.au>
To: Jacky Chou <jacky_chou@...eedtech.com>, andrew@...n.ch, 
	hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net, 
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, joel@....id.au, 
	f.fainelli@...il.com, netdev@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-aspeed@...ts.ozlabs.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2] net: mdio: aspeed: Add dummy read for fire
 control

On Tue, 2024-11-19 at 17:51 +0800, Jacky Chou wrote:
> When the command bus is sometimes busy, it may cause the command is
> not
> arrived to MDIO controller immediately. On software, the driver
> issues a
> write command to the command bus does not wait for command complete
> and
> it returned back to code immediately. But a read command will wait
> for
> the data back, once a read command was back indicates the previous
> write
> command had arrived to controller.
> Add a dummy read to ensure triggering mdio controller before starting
> polling the status of mdio controller to avoid polling unexpected
> timeout.

Why use the explicit dummy read rather than adjust the poll interval or
duration? I still don't think that's been adequately explained given
the hardware-clear of the fire bit on completion, which is what we're
polling for.

Andrew