linux-kernel - Re: [PATCH 02/15] can: m_can: Wakeup net queue once tx was issued

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Message-ID: <20221130172100.ef4xn6j6kzrymdyn@pengutronix.de>
Date:   Wed, 30 Nov 2022 18:21:00 +0100
From:   Marc Kleine-Budde <mkl@...gutronix.de>
To:     Markus Schneider-Pargmann <msp@...libre.com>
Cc:     Chandrasekar Ramakrishnan <rcsekar@...sung.com>,
        Wolfgang Grandegger <wg@...ndegger.com>,
        linux-can@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 02/15] can: m_can: Wakeup net queue once tx was issued

On 16.11.2022 21:52:55, Markus Schneider-Pargmann wrote:
> Currently the driver waits to wakeup the queue until the interrupt for
> the transmit event is received and acknowledged. If we want to use the
> hardware FIFO, this is too late.
> 
> Instead release the queue as soon as the transmit was transferred into
> the hardware FIFO. We are then ready for the next transmit to be
> transferred.

If you want to really speed up the TX path, remove the worker and use
the spi_async() API from the xmit callback, see mcp251xfd_start_xmit().

Extra bonus if you implement xmit_more() and transfer more than 1 skb
per SPI transfer.

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
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