netdev - Re: [PATCH v3 07/16] can: m_can: Implement receive coalescing

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Date:   Thu, 16 Mar 2023 11:04:32 +0100
From:   Simon Horman <simon.horman@...igine.com>
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>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 07/16] can: m_can: Implement receive coalescing

On Wed, Mar 15, 2023 at 12:05:37PM +0100, 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 <simon.horman@...igine.com>