linux-kernel - Re: [net PATCH] net: stmmac: No need to calculate speed divider when offload is disabled

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Date: Sun, 16 Jun 2024 09:15:05 +0800
From: xiaolei wang <xiaolei.wang@...driver.com>
To: Simon Horman <horms@...nel.org>
Cc: olteanv@...il.com, linux@...linux.org.uk, alexandre.torgue@...s.st.com,
        andrew@...n.ch, joabreu@...opsys.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        mcoquelin.stm32@...il.com, wojciech.drewek@...el.com,
        netdev@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [net PATCH] net: stmmac: No need to calculate speed divider when
 offload is disabled


On 6/15/24 22:47, Simon Horman wrote:
> CAUTION: This email comes from a non Wind River email account!
> Do not click links or open attachments unless you recognize the sender and know the content is safe.
>
> On Fri, Jun 14, 2024 at 04:19:16PM +0800, Xiaolei Wang wrote:
>> commit be27b8965297 ("net: stmmac: replace priv->speed with
>> the portTransmitRate from the tc-cbs parameters") introduced
>> a problem. When deleting, it prompts "Invalid portTransmitRate
>> 0 (idleSlope - sendSlope)" and exits. Add judgment on cbs.enable.
>> Only when offload is enabled, speed divider needs to be calculated.
>>
>> Fixes: be27b8965297 ("net: stmmac: replace priv->speed with the portTransmitRate from the tc-cbs parameters")
>> Signed-off-by: Xiaolei Wang <xiaolei.wang@...driver.com>
>> ---
>>   .../net/ethernet/stmicro/stmmac/stmmac_tc.c   | 38 ++++++++++---------
>>   1 file changed, 20 insertions(+), 18 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
>> index 1562fbdd0a04..b0fd2d6e525e 100644
>> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
>> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
>> @@ -358,24 +358,26 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
>>
>>        port_transmit_rate_kbps = qopt->idleslope - qopt->sendslope;
>>
>> -     /* Port Transmit Rate and Speed Divider */
>> -     switch (div_s64(port_transmit_rate_kbps, 1000)) {
>> -     case SPEED_10000:
>> -     case SPEED_5000:
>> -             ptr = 32;
>> -             break;
>> -     case SPEED_2500:
>> -     case SPEED_1000:
>> -             ptr = 8;
>> -             break;
>> -     case SPEED_100:
>> -             ptr = 4;
>> -             break;
>> -     default:
>> -             netdev_err(priv->dev,
>> -                        "Invalid portTransmitRate %lld (idleSlope - sendSlope)\n",
>> -                        port_transmit_rate_kbps);
>> -             return -EINVAL;
>> +     if (qopt->enable) {
>> +             /* Port Transmit Rate and Speed Divider */
>> +             switch (div_s64(port_transmit_rate_kbps, 1000)) {
>> +             case SPEED_10000:
>> +             case SPEED_5000:
>> +                     ptr = 32;
>> +                     break;
>> +             case SPEED_2500:
>> +             case SPEED_1000:
>> +                     ptr = 8;
>> +                     break;
>> +             case SPEED_100:
>> +                     ptr = 4;
>> +                     break;
>> +             default:
>> +                     netdev_err(priv->dev,
>> +                                "Invalid portTransmitRate %lld (idleSlope - sendSlope)\n",
>> +                                port_transmit_rate_kbps);
>> +                     return -EINVAL;
>> +             }
>>        }
>>        mode_to_use = priv->plat->tx_queues_cfg[queue].mode_to_use;
> Hi Xiaolei Wang,
>
> The code following this function looks like this:
>
>          if (mode_to_use == MTL_QUEUE_DCB && qopt->enable) {
>                  ret = stmmac_dma_qmode(priv, priv->ioaddr, queue, MTL_QUEUE_AVB);
>                  if (ret)
>                          return ret;
>                  priv->plat->tx_queues_cfg[queue].mode_to_use = MTL_QUEUE_AVB;
>          } else if (!qopt->enable) {
>                  ret = stmmac_dma_qmode(priv, priv->ioaddr, queue,
>                                         MTL_QUEUE_DCB);
>                  if (ret)
>                          return ret;
>                  priv->plat->tx_queues_cfg[queue].mode_to_use = MTL_QUEUE_DCB;
>          }
>
>          /* Final adjustments for HW */
>          value = div_s64(qopt->idleslope * 1024ll * ptr, port_transmit_rate_kbps);
>          priv->plat->tx_queues_cfg[queue].idle_slope = value & GENMASK(31, 0);
>
>          value = div_s64(-qopt->sendslope * 1024ll * ptr, port_transmit_rate_kbps);
>          priv->plat->tx_queues_cfg[queue].send_slope = value & GENMASK(31, 0);
>
> And the div_s64() lines above appear to use
> ptr uninitialised in the !qopt->enable case.

Oh, when deleting the configuration, idleslope and sendslope are both 0, 
do you mean we also need to set ptr to 0?

thanks

xiaolei

>
> Flagged by Smatch.
>
> --
> pw-bot: changes-requested