Current enetc_set_mm() is designed to set the priv->active_offloads bit
ENETC_F_QBU for enetc_mm_link_state_update() to act on, but if the link
is already up, it modifies the ENETC_MMCSR_ME ("Merge Enable") bit
directly.
The problem is that it only *sets* ENETC_MMCSR_ME if the link is up, it
doesn't *clear* it if needed. So subsequent enetc_get_mm() calls still
see tx-enabled as true, up until a link down event, which is when
enetc_mm_link_state_update() will get called.
This is not a functional issue as far as I can assess. It has only come
up because I'd like to uphold a simple API rule in core ethtool code:
the pMAC cannot be disabled if TX is going to be enabled. Currently,
the fact that TX remains enabled for longer than expected (after the
enetc_set_mm() call that disables it) is going to violate that rule,
which is how it was caught.
Signed-off-by: Vladimir Oltean <[email protected]>
---
v1->v2: none
drivers/net/ethernet/freescale/enetc/enetc_ethtool.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c b/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c
index 838750a03cf6..ee1ea71fe79e 100644
--- a/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c
+++ b/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c
@@ -1041,10 +1041,13 @@ static int enetc_set_mm(struct net_device *ndev, struct ethtool_mm_cfg *cfg,
else
priv->active_offloads &= ~ENETC_F_QBU;
- /* If link is up, enable MAC Merge right away */
- if (!!(priv->active_offloads & ENETC_F_QBU) &&
- !(val & ENETC_MMCSR_LINK_FAIL))
- val |= ENETC_MMCSR_ME;
+ /* If link is up, enable/disable MAC Merge right away */
+ if (!(val & ENETC_MMCSR_LINK_FAIL)) {
+ if (!!(priv->active_offloads & ENETC_F_QBU))
+ val |= ENETC_MMCSR_ME;
+ else
+ val &= ~ENETC_MMCSR_ME;
+ }
val &= ~ENETC_MMCSR_VT_MASK;
val |= ENETC_MMCSR_VT(cfg->verify_time);
--
2.34.1
On Tue, Apr 18, 2023 at 02:14:51PM +0300, Vladimir Oltean wrote:
> Current enetc_set_mm() is designed to set the priv->active_offloads bit
> ENETC_F_QBU for enetc_mm_link_state_update() to act on, but if the link
> is already up, it modifies the ENETC_MMCSR_ME ("Merge Enable") bit
> directly.
>
> The problem is that it only *sets* ENETC_MMCSR_ME if the link is up, it
> doesn't *clear* it if needed. So subsequent enetc_get_mm() calls still
> see tx-enabled as true, up until a link down event, which is when
> enetc_mm_link_state_update() will get called.
>
> This is not a functional issue as far as I can assess. It has only come
> up because I'd like to uphold a simple API rule in core ethtool code:
> the pMAC cannot be disabled if TX is going to be enabled. Currently,
> the fact that TX remains enabled for longer than expected (after the
> enetc_set_mm() call that disables it) is going to violate that rule,
> which is how it was caught.
>
> Signed-off-by: Vladimir Oltean <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
> ---
> v1->v2: none
>
> drivers/net/ethernet/freescale/enetc/enetc_ethtool.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c b/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c
> index 838750a03cf6..ee1ea71fe79e 100644
> --- a/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c
> +++ b/drivers/net/ethernet/freescale/enetc/enetc_ethtool.c
> @@ -1041,10 +1041,13 @@ static int enetc_set_mm(struct net_device *ndev, struct ethtool_mm_cfg *cfg,
> else
> priv->active_offloads &= ~ENETC_F_QBU;
>
> - /* If link is up, enable MAC Merge right away */
> - if (!!(priv->active_offloads & ENETC_F_QBU) &&
> - !(val & ENETC_MMCSR_LINK_FAIL))
> - val |= ENETC_MMCSR_ME;
> + /* If link is up, enable/disable MAC Merge right away */
> + if (!(val & ENETC_MMCSR_LINK_FAIL)) {
> + if (!!(priv->active_offloads & ENETC_F_QBU))
nit: The !!() seems unnecessary,
I wonder if it can be written in a simpler way as:
if (priv->active_offloads & ENETC_F_QBU)
> + val |= ENETC_MMCSR_ME;
> + else
> + val &= ~ENETC_MMCSR_ME;
> + }
>
> val &= ~ENETC_MMCSR_VT_MASK;
> val |= ENETC_MMCSR_VT(cfg->verify_time);
> --
> 2.34.1
>
On Thu, Apr 20, 2023 at 04:22:04PM +0200, Simon Horman wrote:
> > - /* If link is up, enable MAC Merge right away */
> > - if (!!(priv->active_offloads & ENETC_F_QBU) &&
> > - !(val & ENETC_MMCSR_LINK_FAIL))
> > - val |= ENETC_MMCSR_ME;
> > + /* If link is up, enable/disable MAC Merge right away */
> > + if (!(val & ENETC_MMCSR_LINK_FAIL)) {
> > + if (!!(priv->active_offloads & ENETC_F_QBU))
>
> nit: The !!() seems unnecessary,
> I wonder if it can be written in a simpler way as:
>
> if (priv->active_offloads & ENETC_F_QBU)
I agree. Normally I omit the double negation in simple statements like this.
Here I didn't, because the expression was split into 2 "if" conditions,
and I kept the individual terms as-is for some reason.
Since the generated object code is absolutely the same either way, I would not
resend just for minor style comments such as this one, if you don't mind.
However, I do appreciate the review and I'll pay more attention to this
detail in the future.
On Thu, Apr 20, 2023 at 08:03:54PM +0300, Vladimir Oltean wrote:
> On Thu, Apr 20, 2023 at 04:22:04PM +0200, Simon Horman wrote:
> > > - /* If link is up, enable MAC Merge right away */
> > > - if (!!(priv->active_offloads & ENETC_F_QBU) &&
> > > - !(val & ENETC_MMCSR_LINK_FAIL))
> > > - val |= ENETC_MMCSR_ME;
> > > + /* If link is up, enable/disable MAC Merge right away */
> > > + if (!(val & ENETC_MMCSR_LINK_FAIL)) {
> > > + if (!!(priv->active_offloads & ENETC_F_QBU))
> >
> > nit: The !!() seems unnecessary,
> > I wonder if it can be written in a simpler way as:
> >
> > if (priv->active_offloads & ENETC_F_QBU)
>
> I agree. Normally I omit the double negation in simple statements like this.
> Here I didn't, because the expression was split into 2 "if" conditions,
> and I kept the individual terms as-is for some reason.
>
> Since the generated object code is absolutely the same either way, I would not
> resend just for minor style comments such as this one, if you don't mind.
> However, I do appreciate the review and I'll pay more attention to this
> detail in the future.
Thanks. I agree the result should be same.
No need to resend because of this.