From: Marc Kleine-Budde <mkl@pengutronix.de>
To: Markus Schneider-Pargmann <msp@baylibre.com>
Cc: Chandrasekar Ramakrishnan <rcsekar@samsung.com>,
Wolfgang Grandegger <wg@grandegger.com>,
linux-can@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/15] can: m_can: Wakeup net queue once tx was issued
Date: Fri, 2 Dec 2022 14:53:39 +0100 [thread overview]
Message-ID: <20221202135339.k6355z5pxqikd6rg@pengutronix.de> (raw)
In-Reply-To: <20221116205308.2996556-3-msp@baylibre.com>
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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.
>
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> ---
> drivers/net/can/m_can/m_can.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 2c01e3f7b23f..4adf03111782 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -1097,10 +1097,9 @@ static irqreturn_t m_can_isr(int irq, void *dev_id)
> /* New TX FIFO Element arrived */
> if (m_can_echo_tx_event(dev) != 0)
> goto out_fail;
> -
> - if (netif_queue_stopped(dev) &&
> - !m_can_tx_fifo_full(cdev))
> + if (!cdev->tx_skb && netif_queue_stopped(dev))
> netif_wake_queue(dev);
Please don't start the queue if the FIFO is still full. Is this a
gamble, that it will take long enough until the work queue runs that the
FIFO is not full anymore?
> +
Nitpick: Please don't introduce an extra newline here.
> }
> }
>
> @@ -1705,6 +1704,8 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
> if (m_can_tx_fifo_full(cdev) ||
> m_can_next_echo_skb_occupied(dev, putidx))
> netif_stop_queue(dev);
> + else if (cdev->is_peripheral && !cdev->tx_skb && netif_queue_stopped(dev))
> + netif_wake_queue(dev);
Same question as above, what happens if the FIFO is full? e.g. in case
of a slow bus or the first CAN frame in the FIFO has a low prio...
> }
>
> return NETDEV_TX_OK;
> --
> 2.38.1
>
>
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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next prev parent reply other threads:[~2022-12-02 13:53 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-16 20:52 [PATCH 00/15] can: m_can: Optimizations for tcan and peripheral chips Markus Schneider-Pargmann
2022-11-16 20:52 ` [PATCH 01/15] can: m_can: Eliminate double read of TXFQS in tx_handler Markus Schneider-Pargmann
2022-11-16 20:52 ` [PATCH 02/15] can: m_can: Wakeup net queue once tx was issued Markus Schneider-Pargmann
2022-11-30 17:21 ` Marc Kleine-Budde
2022-12-01 8:43 ` Markus Schneider-Pargmann
2022-12-01 9:16 ` Marc Kleine-Budde
2022-12-01 16:49 ` Markus Schneider-Pargmann
2022-12-02 9:16 ` Marc Kleine-Budde
2022-12-14 9:14 ` Markus Schneider-Pargmann
2022-12-14 9:18 ` Marc Kleine-Budde
2022-12-14 9:22 ` Marc Kleine-Budde
2022-12-14 10:15 ` Vincent MAILHOL
2022-12-14 10:35 ` Markus Schneider-Pargmann
2022-12-15 9:31 ` Markus Schneider-Pargmann
2022-12-16 4:40 ` Vincent MAILHOL
2022-12-14 10:18 ` Markus Schneider-Pargmann
2022-12-02 13:53 ` Marc Kleine-Budde [this message]
2022-11-16 20:52 ` [PATCH 03/15] can: m_can: Cache tx putidx and transmits in flight Markus Schneider-Pargmann
2022-12-01 11:14 ` Marc Kleine-Budde
2022-12-02 8:37 ` Markus Schneider-Pargmann
2022-12-02 14:46 ` Marc Kleine-Budde
2022-12-13 17:13 ` Markus Schneider-Pargmann
2022-12-13 19:17 ` Marc Kleine-Budde
2022-12-14 8:32 ` Markus Schneider-Pargmann
2022-11-16 20:52 ` [PATCH 04/15] can: m_can: Use transmit event FIFO watermark level interrupt Markus Schneider-Pargmann
2022-11-30 17:17 ` Marc Kleine-Budde
2022-12-01 8:25 ` Markus Schneider-Pargmann
2022-12-01 9:05 ` Marc Kleine-Budde
2022-12-01 10:12 ` Markus Schneider-Pargmann
2022-12-01 11:00 ` Marc Kleine-Budde
2022-12-01 16:59 ` Markus Schneider-Pargmann
2022-12-02 9:23 ` Marc Kleine-Budde
2022-12-02 9:43 ` Markus Schneider-Pargmann
2022-12-02 14:03 ` Marc Kleine-Budde
2022-12-13 17:19 ` Markus Schneider-Pargmann
2022-12-13 19:18 ` Marc Kleine-Budde
2022-11-16 20:52 ` [PATCH 05/15] can: m_can: Disable unused interrupts Markus Schneider-Pargmann
2022-11-16 20:52 ` [PATCH 06/15] can: m_can: Avoid reading irqstatus twice Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 07/15] can: m_can: Read register PSR only on error Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 08/15] can: m_can: Count TXE FIFO getidx in the driver Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 09/15] can: m_can: Count read getindex " Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 10/15] can: m_can: Batch acknowledge rx fifo Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 11/15] can: m_can: Batch acknowledge transmit events Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 12/15] can: tcan4x5x: Remove invalid write in clear_interrupts Markus Schneider-Pargmann
2022-12-02 14:17 ` Marc Kleine-Budde
2022-11-16 20:53 ` [PATCH 13/15] can: tcan4x5x: Fix use of register error status mask Markus Schneider-Pargmann
2022-12-02 14:19 ` Marc Kleine-Budde
2022-11-16 20:53 ` [PATCH 14/15] can: tcan4x5x: Fix register range of first block Markus Schneider-Pargmann
2022-12-02 14:28 ` Marc Kleine-Budde
2022-12-05 9:30 ` Markus Schneider-Pargmann
2022-12-05 9:44 ` Marc Kleine-Budde
2022-12-05 9:55 ` Markus Schneider-Pargmann
2022-11-16 20:53 ` [PATCH 15/15] can: tcan4x5x: Specify separate read/write ranges Markus Schneider-Pargmann
2022-12-02 14:03 ` [PATCH 00/15] can: m_can: Optimizations for tcan and peripheral chips Marc Kleine-Budde
2022-12-05 9:09 ` Markus Schneider-Pargmann
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