linux-kernel - Re: [PATCH] serial: max310x: rework RX interrupt handling

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Message-ID: <20200930165037.77813365@windsurf.home>
Date:   Wed, 30 Sep 2020 16:50:37 +0200
From:   Thomas Petazzoni <thomas.petazzoni@...tlin.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Jan Kundrát <jan.kundrat@...net.cz>,
        Mark Brown <broonie@...nel.org>,
        linux-spi <linux-spi@...r.kernel.org>
Subject: Re: [PATCH] serial: max310x: rework RX interrupt handling

Hello,

On Wed, 30 Sep 2020 17:24:48 +0300
Andy Shevchenko <andy.shevchenko@...il.com> wrote:

> > On a Microchip SAMA5D3 platform that is receiving 20 bytes every 16ms
> > over one MAX310X UART, this patch has allowed to reduce the CPU
> > consumption of the interrupt handler thread from ~25% to 6-7%.  
> 
> Was it always like this?

As far as I can see, yes. I guess you were thinking about a Fixes: tag
perhaps? I don't think a Fixes: tag really applies here, as we're not
fixing a performance regression.

> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> > -       /* Configure MODE2 register & Reset FIFOs*/
> > -       val = MAX310X_MODE2_RXEMPTINV_BIT | MAX310X_MODE2_FIFORST_BIT;
> > -       max310x_port_write(port, MAX310X_MODE2_REG, val);
> > +       /* Reset FIFOs*/  
> 
> Add a space before the asterisk.

Indeed. Let me know if a v2 is needed, or if this small typo can be
fixed when applying.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com