linux-kernel - Re: [PATCH v6 04/14] can: m_can: Implement receive coalescing

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Message-ID: <20231001122316.GL92317@kernel.org>
Date:   Sun, 1 Oct 2023 14:23:16 +0200
From:   Simon Horman <horms@...nel.org>
To:     Markus Schneider-Pargmann <msp@...libre.com>
Cc:     Marc Kleine-Budde <mkl@...gutronix.de>,
        Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        Vincent MAILHOL <mailhol.vincent@...adoo.fr>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-can@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Julien Panis <jpanis@...libre.com>, Judith Mendez <jm@...com>
Subject: Re: [PATCH v6 04/14] can: m_can: Implement receive coalescing

On Fri, Sep 29, 2023 at 04:12:54PM +0200, Markus Schneider-Pargmann wrote:
> m_can offers the possibility to set an interrupt on reaching a watermark
> level in the receive FIFO. This can be used to implement coalescing.
> Unfortunately there is no hardware timeout available to trigger an
> interrupt if only a few messages were received within a given time. To
> solve this I am using a hrtimer to wake up the irq thread after x
> microseconds.
> 
> The timer is always started if receive coalescing is enabled and new
> received frames were available during an interrupt. The timer is stopped
> if during a interrupt handling no new data was available.
> 
> If the timer is started the new item interrupt is disabled and the
> watermark interrupt takes over. If the timer is not started again, the
> new item interrupt is enabled again, notifying the handler about every
> new item received.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>

Reviewed-by: Simon Horman <horms@...nel.org>