Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Thu, 1 Dec 2022 09:43:02 +0100
From:   Markus Schneider-Pargmann <msp@baylibre.com>
To:     Marc Kleine-Budde <mkl@pengutronix.de>
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
Message-ID: <20221201084302.oodh22xgvwsjmoc3@blmsp>
References: <20221116205308.2996556-1-msp@baylibre.com>
 <20221116205308.2996556-3-msp@baylibre.com>
 <20221130172100.ef4xn6j6kzrymdyn@pengutronix.de>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <20221130172100.ef4xn6j6kzrymdyn@pengutronix.de>
Precedence: bulk

Hi Marc,

On Wed, Nov 30, 2022 at 06:21:00PM +0100, Marc Kleine-Budde wrote:
> 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().

Good idea. I will check how regmap's async_write works and if it is
suitable to do the job. I don't want to drop the regmap usage for this
right now.

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

That's on my todo list, but I am not sure I will get to it soonish.

Thank you Marc!.

Best,
Markus