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

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Message-ID:
 <SEYPR06MB513421BF046C1478303E8C299D212@SEYPR06MB5134.apcprd06.prod.outlook.com>
Date: Wed, 20 Nov 2024 02:34:56 +0000
From: Jacky Chou <jacky_chou@...eedtech.com>
To: Andrew Lunn <andrew@...n.ch>
CC: "hkallweit1@...il.com" <hkallweit1@...il.com>, "linux@...linux.org.uk"
	<linux@...linux.org.uk>, "davem@...emloft.net" <davem@...emloft.net>,
	"edumazet@...gle.com" <edumazet@...gle.com>, "kuba@...nel.org"
	<kuba@...nel.org>, "pabeni@...hat.com" <pabeni@...hat.com>, "joel@....id.au"
	<joel@....id.au>, "andrew@...econstruct.com.au"
	<andrew@...econstruct.com.au>, "f.fainelli@...il.com" <f.fainelli@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-aspeed@...ts.ozlabs.org"
	<linux-aspeed@...ts.ozlabs.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject:
 回覆: [PATCH net v2] net: mdio: aspeed: Add dummy read for fire control

Hi Andrew Lunn,

Thank you for your reply.

> > 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.
> 
> Please have another attempt at writing the commit message.
> 
> > Fixes: a9770eac511a ("net: mdio: Move MDIO drivers into a new
> > subdirectory")
> > Signed-off-by: Jacky Chou <jacky_chou@...eedtech.com>
> > ---
> >  drivers/net/mdio/mdio-aspeed.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/mdio/mdio-aspeed.c
> > b/drivers/net/mdio/mdio-aspeed.c index c2170650415c..373902d33b96
> > 100644
> > --- a/drivers/net/mdio/mdio-aspeed.c
> > +++ b/drivers/net/mdio/mdio-aspeed.c
> > @@ -62,6 +62,8 @@ static int aspeed_mdio_op(struct mii_bus *bus, u8 st,
> u8 op, u8 phyad, u8 regad,
> >  		| FIELD_PREP(ASPEED_MDIO_DATA_MIIRDATA, data);
> >
> >  	iowrite32(ctrl, ctx->base + ASPEED_MDIO_CTRL);
> > +	/* Add dummy read to ensure triggering mdio controller */
> > +	(void)ioread32(ctx->base + ASPEED_MDIO_CTRL);
> 
> Maybe: /* Dummy read to flush previous write to controller */

Agree. I will change the title in next version.

Thanks,
Jacky