Messages in this thread | | | Subject | Re: [PATCH] can: c_can: Speed up rx_poll function | From | Joe Perches <> | Date | Mon, 28 Oct 2013 10:12:16 -0700 |
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On Mon, 2013-10-28 at 17:59 +0100, Markus Pargmann wrote: > This patch speeds up the rx_poll function by reducing the number of > register reads.
trivial notes:
> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c [] > @@ -259,6 +259,12 @@ static u32 c_can_read_reg32(struct c_can_priv *priv, enum reg index) > +u16 c_can_read_reg16(struct c_can_priv *priv, enum reg index) > +{ > + u16 val = priv->read_reg(priv, index); > + return val; > +}
This function doesn't seem useful at all. It's not exported and it's not static.
Why not use an in-place priv->read_reg(priv, index)?
> + > static void c_can_enable_all_interrupts(struct c_can_priv *priv, > int enable) > { > @@ -798,17 +804,21 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota) > u32 num_rx_pkts = 0; > unsigned int msg_obj, msg_ctrl_save; > struct c_can_priv *priv = netdev_priv(dev); > - u32 val = c_can_read_reg32(priv, C_CAN_INTPND1_REG); > + unsigned long val = c_can_read_reg16(priv, C_CAN_INTPND1_REG);
Probably better as a u16 as detailed below.
> + /* > + * It is faster to read only one 16bit register. This is only possible > + * for a maximum number of 16 objects. > + */ > + BUILD_BUG_ON_MSG(C_CAN_MSG_OBJ_RX_LAST > 16, > + "Implementation does not support more message objects than 16"); > + > + while (quota > 0 && (val = c_can_read_reg16(priv, C_CAN_INTPND1_REG))) { > + msg_obj = 0; > + while ((msg_obj = find_next_bit(&val, 16, msg_obj)) < 16 &&
Using ffs instead of find_next_bit would be more standard and probably faster too.
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