linux-kernel - Re: [PATCH v7 18/34] i2c: tegra: Remove likely/unlikely from the code

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Date:   Thu, 17 Sep 2020 14:41:20 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        linux-i2c@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 18/34] i2c: tegra: Remove likely/unlikely from the code

On Wed, Sep 09, 2020 at 01:39:50AM +0300, Dmitry Osipenko wrote:
> The likely/unlikely annotations should be used only in a hot paths of
> performance-critical code. The I2C driver doesn't have such paths, and
> thus, there is no justification for usage of likely/unlikely annotations
> in the code. Hence remove them.
> 
> Reviewed-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/i2c/busses/i2c-tegra.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index ab83d1de6c94..fd0d51ec447f 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -852,7 +852,7 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
>  		goto err;
>  	}
>  
> -	if (unlikely(status & status_err)) {
> +	if (status & status_err) {
>  		tegra_i2c_disable_packet_mode(i2c_dev);
>  		if (status & I2C_INT_NO_ACK)
>  			i2c_dev->msg_err |= I2C_ERR_NO_ACK;

At least this one is an interrupt handler, so it's kind of performance
critical. That said, it probably doesn't make a huge difference, so I
don't have any objection:

Acked-by: Thierry Reding <treding@...dia.com>

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