Message-ID: <389230ed31212b2c9e242c9d2f55489aadc89bd1.camel@oss.nxp.com>
Subject: Re: [PATCH 3/3] phy: nxp-c45-tja11xx: read the tx timestamp without
 lock
From:   "Radu Nicolae Pirea (NXP OSS)" <radu-nicolae.pirea@oss.nxp.com>
To:     Andrew Lunn <andrew@lunn.ch>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        christian.herber@nxp.com, hkallweit1@gmail.com,
        linux@armlinux.org.uk, davem@davemloft.net, kuba@kernel.org
Date:   Wed, 22 Dec 2021 10:19:30 +0200
In-Reply-To: <YcCc84XAlckpTnkF@lunn.ch>
References: <20211220120859.140453-1-radu-nicolae.pirea@oss.nxp.com>
         <20211220120859.140453-3-radu-nicolae.pirea@oss.nxp.com>
         <YcCc84XAlckpTnkF@lunn.ch>
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On Mon, 2021-12-20 at 16:10 +0100, Andrew Lunn wrote:
> On Mon, Dec 20, 2021 at 02:08:59PM +0200, Radu Pirea (NXP OSS) wrote:
> > The tx timestamps are read from only one place in interrupt or
> > polling
> > mode. Locking the mutex is useless.
> 
> You cannot take a mutex in an interrupt handler. So your description
> is probably not accurate.
Actually this is the second issue.
I will improve the description.
> 
> Is it safe for other ptp operations to be performed in parallel with
> reading the TX timestamp? _nxp_c45_ptp_settime64()?
Yes, it's safe. The purpose of the mutex is to protect the access to
LTC(PTP counter).
> 
>         Andrew