diff mbox series

[v3,11/16] can: m_can: Cache tx putidx

Message ID 20230315110546.2518305-12-msp@baylibre.com
State New
Headers
Series can: m_can: Optimizations for m_can/tcan part 2 |

Commit Message

Markus Schneider-Pargmann March 15, 2023, 11:05 a.m. UTC 
  m_can_tx_handler is the only place where data is written to the tx fifo.
We can calculate the putidx in the driver code here to avoid the
dependency on the txfqs register.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---
 drivers/net/can/m_can/m_can.c | 8 +++++++-
 drivers/net/can/m_can/m_can.h | 3 +++
 2 files changed, 10 insertions(+), 1 deletion(-)

Comments

Simon Horman March 16, 2023, 9:55 a.m. UTC | #1 
On Wed, Mar 15, 2023 at 12:05:41PM +0100, Markus Schneider-Pargmann wrote:
> m_can_tx_handler is the only place where data is written to the tx fifo.
> We can calculate the putidx in the driver code here to avoid the
> dependency on the txfqs register.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> ---
>  drivers/net/can/m_can/m_can.c | 8 +++++++-
>  drivers/net/can/m_can/m_can.h | 3 +++
>  2 files changed, 10 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 4e794166664a..d5bcce948d2c 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -1475,6 +1475,10 @@ static int m_can_start(struct net_device *dev)
>  
>  	m_can_enable_all_interrupts(cdev);
>  
> +	if (cdev->version > 30)
> +		cdev->tx_fifo_putidx = FIELD_GET(TXFQS_TFQPI_MASK,
> +						 m_can_read(cdev, M_CAN_TXFQS));
> +
>  	return 0;
>  }
>  
> @@ -1765,7 +1769,7 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
>  		}
>  
>  		/* get put index for frame */
> -		putidx = FIELD_GET(TXFQS_TFQPI_MASK, txfqs);
> +		putidx = cdev->tx_fifo_putidx;
>  
>  		/* Construct DLC Field, with CAN-FD configuration.
>  		 * Use the put index of the fifo as the message marker,
> @@ -1798,6 +1802,8 @@ static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
>  
>  		/* Enable TX FIFO element to start transfer  */
>  		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
> +		cdev->tx_fifo_putidx = (++cdev->tx_fifo_putidx >= cdev->can.echo_skb_max ?
> +					0 : cdev->tx_fifo_putidx);
>  
>  		/* stop network queue if fifo full */
>  		if (m_can_tx_fifo_full(cdev) ||
> diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
> index d0c21eddb6ec..548ae908ac4e 100644
> --- a/drivers/net/can/m_can/m_can.h
> +++ b/drivers/net/can/m_can/m_can.h
> @@ -102,6 +102,9 @@ struct m_can_classdev {
>  	u32 tx_max_coalesced_frames_irq;
>  	u32 tx_coalesce_usecs_irq;
>  
> +	// Store this internally to avoid fetch delays on peripheral chips
> +	int tx_fifo_putidx;

nit: it might be slightly nicer to do a pass over the code
     and make putidx unsigned - assuming it is an unsigned value.

> +
>  	struct mram_cfg mcfg[MRAM_CFG_NUM];
>  };
>  
> -- 
> 2.39.2
>
Simon Horman March 16, 2023, 10:08 a.m. UTC | #2 
On Thu, Mar 16, 2023 at 10:55:00AM +0100, Simon Horman wrote:
> On Wed, Mar 15, 2023 at 12:05:41PM +0100, Markus Schneider-Pargmann wrote:
> > m_can_tx_handler is the only place where data is written to the tx fifo.
> > We can calculate the putidx in the driver code here to avoid the
> > dependency on the txfqs register.
> > 
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>

Nit in my previous email (which I hit send on a little too soon)
not withstanding,

Signed-off-by: Simon Horman <simon.horman@corigine.com>

FWIIW, I am taking a pause in my review now.

...

> > diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
> > index d0c21eddb6ec..548ae908ac4e 100644
> > --- a/drivers/net/can/m_can/m_can.h
> > +++ b/drivers/net/can/m_can/m_can.h
> > @@ -102,6 +102,9 @@ struct m_can_classdev {
> >  	u32 tx_max_coalesced_frames_irq;
> >  	u32 tx_coalesce_usecs_irq;
> >  
> > +	// Store this internally to avoid fetch delays on peripheral chips
> > +	int tx_fifo_putidx;
> 
> nit: it might be slightly nicer to do a pass over the code
>      and make putidx unsigned - assuming it is an unsigned value.
> 
> > +
> >  	struct mram_cfg mcfg[MRAM_CFG_NUM];
> >  };
> >  
> > -- 
> > 2.39.2
> >
diff mbox series

Patch

diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 4e794166664a..d5bcce948d2c 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1475,6 +1475,10 @@  static int m_can_start(struct net_device *dev)
 
 	m_can_enable_all_interrupts(cdev);
 
+	if (cdev->version > 30)
+		cdev->tx_fifo_putidx = FIELD_GET(TXFQS_TFQPI_MASK,
+						 m_can_read(cdev, M_CAN_TXFQS));
+
 	return 0;
 }
 
@@ -1765,7 +1769,7 @@  static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 		}
 
 		/* get put index for frame */
-		putidx = FIELD_GET(TXFQS_TFQPI_MASK, txfqs);
+		putidx = cdev->tx_fifo_putidx;
 
 		/* Construct DLC Field, with CAN-FD configuration.
 		 * Use the put index of the fifo as the message marker,
@@ -1798,6 +1802,8 @@  static netdev_tx_t m_can_tx_handler(struct m_can_classdev *cdev)
 
 		/* Enable TX FIFO element to start transfer  */
 		m_can_write(cdev, M_CAN_TXBAR, (1 << putidx));
+		cdev->tx_fifo_putidx = (++cdev->tx_fifo_putidx >= cdev->can.echo_skb_max ?
+					0 : cdev->tx_fifo_putidx);
 
 		/* stop network queue if fifo full */
 		if (m_can_tx_fifo_full(cdev) ||
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index d0c21eddb6ec..548ae908ac4e 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -102,6 +102,9 @@  struct m_can_classdev {
 	u32 tx_max_coalesced_frames_irq;
 	u32 tx_coalesce_usecs_irq;
 
+	// Store this internally to avoid fetch delays on peripheral chips
+	int tx_fifo_putidx;
+
 	struct mram_cfg mcfg[MRAM_CFG_NUM];
 };