lkml.org 
[lkml]   [2013]   [Oct]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC] net: stmmac: keep RXC running in LPI mode to avoid system overload
Hello Romain

On 10/8/2013 5:06 PM, Romain Baeriswyl wrote:
> In order to avoid system overload, the clock RXC from the Phy should not be
> stopped when in LPI mode.
>
> With the RTL8211E PHY which support EEE mode and with Apple Airport Extreme that
> supports it also, the kernel get frozen as soon as some Ethernet transfers are


hmm, I have a board with this transceiver so I could do some tests
this could take a while, unfortunately.

> on-going. System seems to be overloaded with too many interrupts. The 'top'
> command reports often around ~80% irq.

do you mean lpi mac interrupts?

>
> By letting the RXC clock running even in LPI mode as proposed below, the issue
> seems solved. Is it the right way to proceed?

For EEE capability, RX_CLK may be halted for this reason i used it as
default in the stmmac and never seen your issue.

>
> What is the power impact to not stop RXC in LPI mode?

I can point you to "22.2.2.8a Receive direction LPI transition"
in IEEE802-3az... where is it reported that the PHY halt the RX_CLK
in LPI mode.

May I suspect some issues on your HW? or disable it with ethtool


peppe

>
> ---
> drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 ++++--
> 1 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index e9eab29..d40d26b 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -314,7 +314,8 @@ bool stmmac_eee_init(struct stmmac_priv *priv)
> /* MAC core supports the EEE feature. */
> if (priv->dma_cap.eee) {
> /* Check if the PHY supports EEE */
> - if (phy_init_eee(priv->phydev, 1))
> + /* Keeps RXC running in LPI mode to avoid stability issue */
> + if (phy_init_eee(priv->phydev, 0))
> goto out;
>
> if (!priv->eee_active) {
> @@ -770,7 +771,8 @@ static void stmmac_adjust_link(struct net_device *dev)
> /* At this stage, it could be needed to setup the EEE or adjust some
> * MAC related HW registers.
> */
> - priv->eee_enabled = stmmac_eee_init(priv);
> + if (new_state)
> + priv->eee_enabled = stmmac_eee_init(priv);

this seems out of context and not necessary

>
> spin_unlock_irqrestore(&priv->lock, flags);
> }
>



\
 
 \ /
  Last update: 2013-10-09 17:41    [W:0.042 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site