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Date:   Tue, 4 Jan 2022 11:54:47 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Tomasz =?utf-8?Q?Mo=C5=84?= <tomasz.mon@camlingroup.com>
Cc:     linux-serial@vger.kernel.org, Jiri Slaby <jirislaby@kernel.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        k.drobinski@camlintechnologies.com
Subject: Re: [PATCH] serial: imx: reduce RX interrupt frequency
Message-ID: <YdQndwYc9xaauvpS@kroah.com>
References: <20220104103203.2033673-1-tomasz.mon@camlingroup.com>
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On Tue, Jan 04, 2022 at 11:32:03AM +0100, Tomasz Moń wrote:
> Triggering RX interrupt for every byte defeats the purpose of aging
> timer and leads to interrupt starvation at high baud rates.
> 
> Increase receiver trigger level to 8 to increase the minimum period
> between RX interrupts to 8 characters time. The tradeoff is increased
> latency. In the worst case scenario, where RX data has intercharacter
> delay slightly less than aging timer (8 characters time), it can take
> up to 63 characters time for the interrupt to be raised since the
> reception of the first character.

Why can't you do this dynamically based on the baud rate so as to always
work properly for all speeds without increased delays for slower ones?

thanks,

greg k-h