On Tue, 5 May 2020 22:20:52 +0300, Vladimir Oltean <olte...@gmail.com> wrote:
> From: Vladimir Oltean <vladimir.olt...@nxp.com>
>
> As its implementation shows, this is synonimous with calling
> dsa_slave_dev_check followed by dsa_slave_to_port, so it is quite simple
> already and provides functionality which is already there.
>
> However there is now a need for these functions outside dsa_priv.h, for
> example in drivers that perform mirroring and redirection through
> tc-flower offloads (they are given raw access to the flow_cls_offload
> structure), where they need to call this function on act->dev.
>
> But simply exporting dsa_slave_to_port would make it non-inline and
> would result in an extra function call in the hotpath, as can be seen
> for example in sja1105:
>
> Before:
>
> 000006dc <sja1105_xmit>:
> {
> 6dc: e92d4ff0 push {r4, r5, r6, r7, r8, r9, sl, fp, lr}
> 6e0: e1a04000 mov r4, r0
> 6e4: e591958c ldr r9, [r1, #1420] ; 0x58c <- Inline
> dsa_slave_to_port
> 6e8: e1a05001 mov r5, r1
> 6ec: e24dd004 sub sp, sp, #4
> u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
> 6f0: e1c901d8 ldrd r0, [r9, #24]
> 6f4: ebfffffe bl 0 <dsa_8021q_tx_vid>
> 6f4: R_ARM_CALL dsa_8021q_tx_vid
> u8 pcp = netdev_txq_to_tc(netdev, queue_mapping);
> 6f8: e1d416b0 ldrh r1, [r4, #96] ; 0x60
> u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
> 6fc: e1a08000 mov r8, r0
>
> After:
>
> 000006e4 <sja1105_xmit>:
> {
> 6e4: e92d4ff0 push {r4, r5, r6, r7, r8, r9, sl, fp, lr}
> 6e8: e1a04000 mov r4, r0
> 6ec: e24dd004 sub sp, sp, #4
> struct dsa_port *dp = dsa_slave_to_port(netdev);
> 6f0: e1a00001 mov r0, r1
> {
> 6f4: e1a05001 mov r5, r1
> struct dsa_port *dp = dsa_slave_to_port(netdev);
> 6f8: ebfffffe bl 0 <dsa_slave_to_port>
> 6f8: R_ARM_CALL dsa_slave_to_port
> 6fc: e1a09000 mov r9, r0
> u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index);
> 700: e1c001d8 ldrd r0, [r0, #24]
> 704: ebfffffe bl 0 <dsa_8021q_tx_vid>
> 704: R_ARM_CALL dsa_8021q_tx_vid
>
> Because we want to avoid possible performance regressions, introduce
> this new function which is designed to be public.
>
> Suggested-by: Vivien Didelot <vivien.dide...@gmail.com>
> Signed-off-by: Vladimir Oltean <vladimir.olt...@nxp.com>
Reviewed-by: Vivien Didelot <vivien.dide...@gmail.com>
