Re: [PATCH] net: davinci_emac: Fix interrupt pacing disable

[Maxim Kiselev]

Yes, I can write 0 to INTCTRL for ` case EMAC_VERSION_2` but we also
need to handle `default case`

пн, 1 нояб. 2021 г. в 14:54, Grygorii Strashko <grygorii.strashko@xxxxxx>:
>
>
>
> On 01/11/2021 11:21, Maxim Kiselev wrote:
> > This patch allows to use 0 for `coal->rx_coalesce_usecs` param to
> > disable rx irq coalescing.
> >
> > Previously we could enable rx irq coalescing via ethtool
> > (For ex: `ethtool -C eth0 rx-usecs 2000`) but we couldn't disable
> > it because this part rejects 0 value:
> >
> >         if (!coal->rx_coalesce_usecs)
> >                 return -EINVAL;
> >
> > Fixes: 84da2658a619 ("TI DaVinci EMAC : Implement interrupt pacing
> > functionality.")
> >
> > Signed-off-by: Maxim Kiselev <bigunclemax@xxxxxxxxx>
> > ---
> >   drivers/net/ethernet/ti/davinci_emac.c | 77 ++++++++++++++------------
> >   1 file changed, 41 insertions(+), 36 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/ti/davinci_emac.c b/drivers/net/ethernet/ti/davinci_emac.c
> > index e8291d8488391..a3a02c4e5eb68 100644
> > --- a/drivers/net/ethernet/ti/davinci_emac.c
> > +++ b/drivers/net/ethernet/ti/davinci_emac.c
> > @@ -417,46 +417,47 @@ static int emac_set_coalesce(struct net_device *ndev,
> >                            struct netlink_ext_ack *extack)
> >   {
> >       struct emac_priv *priv = netdev_priv(ndev);
> > -     u32 int_ctrl, num_interrupts = 0;
> > +     u32 int_ctrl = 0, num_interrupts = 0;
> >       u32 prescale = 0, addnl_dvdr = 1, coal_intvl = 0;
> >
> > -     if (!coal->rx_coalesce_usecs)
> > -             return -EINVAL;
> > -
> >       coal_intvl = coal->rx_coalesce_usecs;
>
> Wouldn't be more simple if you just handle !coal->rx_coalesce_usecs here and exit?
> it seems you can just write 0 t0 INTCTRL.
>
> >
> >       switch (priv->version) {
> >       case EMAC_VERSION_2:
> > -             int_ctrl =  emac_ctrl_read(EMAC_DM646X_CMINTCTRL);
> > -             prescale = priv->bus_freq_mhz * 4;
> > -
> > -             if (coal_intvl < EMAC_DM646X_CMINTMIN_INTVL)
> > -                     coal_intvl = EMAC_DM646X_CMINTMIN_INTVL;
> > -
> > -             if (coal_intvl > EMAC_DM646X_CMINTMAX_INTVL) {
> > -                     /*
> > -                      * Interrupt pacer works with 4us Pulse, we can
> > -                      * throttle further by dilating the 4us pulse.
> > -                      */
> > -                     addnl_dvdr = EMAC_DM646X_INTPRESCALE_MASK / prescale;
> > -
> > -                     if (addnl_dvdr > 1) {
> > -                             prescale *= addnl_dvdr;
> > -                             if (coal_intvl > (EMAC_DM646X_CMINTMAX_INTVL
> > -                                                     * addnl_dvdr))
> > -                                     coal_intvl = (EMAC_DM646X_CMINTMAX_INTVL
> > -                                                     * addnl_dvdr);
> > -                     } else {
> > -                             addnl_dvdr = 1;
> > -                             coal_intvl = EMAC_DM646X_CMINTMAX_INTVL;
> > +             if (coal->rx_coalesce_usecs) {
> > +                     int_ctrl =  emac_ctrl_read(EMAC_DM646X_CMINTCTRL);
> > +                     prescale = priv->bus_freq_mhz * 4;
> > +
> > +                     if (coal_intvl < EMAC_DM646X_CMINTMIN_INTVL)
> > +                             coal_intvl = EMAC_DM646X_CMINTMIN_INTVL;
> > +
> > +                     if (coal_intvl > EMAC_DM646X_CMINTMAX_INTVL) {
> > +                             /*
> > +                              * Interrupt pacer works with 4us Pulse, we can
> > +                              * throttle further by dilating the 4us pulse.
> > +                              */
> > +                             addnl_dvdr =
> > +                                     EMAC_DM646X_INTPRESCALE_MASK / prescale;
> > +
> > +                             if (addnl_dvdr > 1) {
> > +                                     prescale *= addnl_dvdr;
> > +                                     if (coal_intvl > (EMAC_DM646X_CMINTMAX_INTVL
> > +                                                             * addnl_dvdr))
> > +                                             coal_intvl = (EMAC_DM646X_CMINTMAX_INTVL
> > +                                                             * addnl_dvdr);
> > +                             } else {
> > +                                     addnl_dvdr = 1;
> > +                                     coal_intvl = EMAC_DM646X_CMINTMAX_INTVL;
> > +                             }
> >                       }
> > -             }
> >
> > -             num_interrupts = (1000 * addnl_dvdr) / coal_intvl;
> > +                     num_interrupts = (1000 * addnl_dvdr) / coal_intvl;
> > +
> > +                     int_ctrl |= EMAC_DM646X_INTPACEEN;
> > +                     int_ctrl &= (~EMAC_DM646X_INTPRESCALE_MASK);
> > +                     int_ctrl |= (prescale & EMAC_DM646X_INTPRESCALE_MASK);
> > +             }
> >
> > -             int_ctrl |= EMAC_DM646X_INTPACEEN;
> > -             int_ctrl &= (~EMAC_DM646X_INTPRESCALE_MASK);
> > -             int_ctrl |= (prescale & EMAC_DM646X_INTPRESCALE_MASK);
> >               emac_ctrl_write(EMAC_DM646X_CMINTCTRL, int_ctrl);
> >
> >               emac_ctrl_write(EMAC_DM646X_CMRXINTMAX, num_interrupts);
> > @@ -466,17 +467,21 @@ static int emac_set_coalesce(struct net_device *ndev,
> >       default:
> >               int_ctrl = emac_ctrl_read(EMAC_CTRL_EWINTTCNT);
> >               int_ctrl &= (~EMAC_DM644X_EWINTCNT_MASK);
> > -             prescale = coal_intvl * priv->bus_freq_mhz;
> > -             if (prescale > EMAC_DM644X_EWINTCNT_MASK) {
> > -                     prescale = EMAC_DM644X_EWINTCNT_MASK;
> > -                     coal_intvl = prescale / priv->bus_freq_mhz;
> > +
> > +             if (coal->rx_coalesce_usecs) {
> > +                     prescale = coal_intvl * priv->bus_freq_mhz;
> > +                     if (prescale > EMAC_DM644X_EWINTCNT_MASK) {
> > +                             prescale = EMAC_DM644X_EWINTCNT_MASK;
> > +                             coal_intvl = prescale / priv->bus_freq_mhz;
> > +                     }
> >               }
> > +
> >               emac_ctrl_write(EMAC_CTRL_EWINTTCNT, (int_ctrl | prescale));
> >
> >               break;
> >       }
> >
> > -     printk(KERN_INFO"Set coalesce to %d usecs.\n", coal_intvl);
> > +     netdev_info(ndev, "Set coalesce to %d usecs.\n", coal_intvl);
> >       priv->coal_intvl = coal_intvl;
> >
> >       return 0;
> >
>
> --
> Best regards,
> grygorii