netdev - Re: [PATCH net-next v3 7/7] net: phy: use phy_read_poll

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Date:   Sat, 21 Mar 2020 19:57:11 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Dejin Zheng <zhengdejin5@...il.com>, andrew@...n.ch,
        hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
        allison@...utok.net, tglx@...utronix.de,
        gregkh@...uxfoundation.org, mchehab+samsung@...nel.org,
        netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 7/7] net: phy: use phy_read_poll_timeout() to
 simplify the code



On 3/21/2020 7:48 PM, Dejin Zheng wrote:
> use phy_read_poll_timeout() to replace the poll codes for
> simplify the code in phy_poll_reset() function.
> 
> Signed-off-by: Dejin Zheng <zhengdejin5@...il.com>
> ---
> v2 -> v3:
> 	- adapt to it after modifying the parameter order of the
> 	  newly added function
> v1 -> v2:
> 	- remove the handle of phy_read()'s return error.
> 
>  drivers/net/phy/phy_device.c | 16 ++++------------
>  1 file changed, 4 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
> index a585faf8b844..cfe7aae35084 100644
> --- a/drivers/net/phy/phy_device.c
> +++ b/drivers/net/phy/phy_device.c
> @@ -1059,23 +1059,15 @@ EXPORT_SYMBOL(phy_disconnect);
>  static int phy_poll_reset(struct phy_device *phydev)
>  {
>  	/* Poll until the reset bit clears (50ms per retry == 0.6 sec) */
> -	unsigned int retries = 12;
> -	int ret;
> -
> -	do {
> -		msleep(50);
> -		ret = phy_read(phydev, MII_BMCR);

You are doing some subtle changes here, the sleep used to be *before*
the read of BMCR and now it will be *after*. If there were PHY devices
that required 50ms at least, but would incorrectly return that
BMCR_RESET is cleared *before* 50ms, then we would be breaking those.

I would recommend we drop this patch for now, the rest looks good to me
though.
-- 
Florian