linux-kernel - Re: [PATCH v2] net: ocelot: fix wrong time

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Message-ID: <4d08b849-3e79-7c82-803c-51c251344c7a@gmail.com>
Date:   Mon, 27 Jun 2022 17:46:10 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     Clément Léger <clement.leger@...tlin.com>,
        Vladimir Oltean <vladimir.oltean@....com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Claudiu Manoil <claudiu.manoil@....com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "UNGLinuxDriver@...rochip.com" <UNGLinuxDriver@...rochip.com>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] net: ocelot: fix wrong time_after usage

On 6/24/22 18:14, Clément Léger wrote:
> So I actually tested and added logging to see if the CH_SAFE
> register bits are set for the channel on the first iteration. From
> what I could test (iperf3 with huge/non huge packets, TCP/UDP), it
> always return true on the first try. So since I think Pavel solution
> is ok to go with.
> 
> However, since ocelot_fdma_wait_chan_safe() is also called in the napi
> poll function of this driver, I don't think sleeping is allowed (softirq
> context) and thus I would suggest using the readx_poll_timeout_atomic()
> function instead.
> 
> Regarding the delay to wait between each read, I don't have any
> information about that possible value, the datasheet only says "wait
> for the bit to be set" so I guess we'll have to live with an
> approximate value.
> 

Thank you for testing!

I will update update v3 with _atomic variant



Thanks,
--Pavel Skripkin