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Date: Mon, 1 Nov 2021 14:33:51 +0200
From: Grygorii Strashko <grygorii.strashko@...com>
To: Maxim Kiselev <bigunclemax@...il.com>
CC: "David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
Yang Yingliang <yangyingliang@...wei.com>,
Colin Ian King <colin.king@...onical.com>,
Yufeng Mo <moyufeng@...wei.com>,
Michael Walle <michael@...le.cc>, Sriram <srk@...com>,
<linux-omap@...r.kernel.org>, <netdev@...r.kernel.org>,
<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] net: davinci_emac: Fix interrupt pacing disable
On 01/11/2021 14:05, Maxim Kiselev wrote:
> Yes, I can write 0 to INTCTRL for ` case EMAC_VERSION_2` but we also
> need to handle `default case`
pls, do not top post.
>
> пн, 1 нояб. 2021 г. в 14:54, Grygorii Strashko <grygorii.strashko@...com>:
>>
>>
>>
>> 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@...il.com>
>>> ---
>>> 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.
nothing prevents you from handling all cases here, like
if (!coal->rx_coalesce_usecs)
switch (priv->version) {
case EMAC_VERSION_2:
emac_ctrl_write(EMAC_DM646X_CMINTCTRL, 0);
break;
default:
emac_ctrl_write(EMAC_CTRL_EWINTTCNT, 0);
break;
}
return 0;
}
No?
>>
>>>
>>> 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
--
Best regards,
grygorii
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