netdev - Re: [PATCH] net: ethernet: cpsw: fix usage of cpdma_check_free_tx

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Message-ID: <20130312202027.GA935@blumentopf>
Date:	Tue, 12 Mar 2013 21:20:27 +0100
From:	Andreas Fenkart <andreas.fenkart@...eamunlimited.com>
To:	Mugunthan V N <mugunthanvnm@...com>
Cc:	Daniel Mack <zonque@...il.com>, netdev@...r.kernel.org,
	andreas.fenkart@...eamunlimited.com, davem@...emloft.net,
	s.neumann@...mfeld.com, koen@...inion.thruhere.net
Subject: Re: [PATCH] net: ethernet: cpsw: fix usage of
 cpdma_check_free_tx_desc()

On Wed, Mar 13, 2013 at 01:17:44AM +0530, Mugunthan V N wrote:
> On 3/12/2013 10:01 PM, Daniel Mack wrote:
> >Commit fae50823d0 ("net: ethernet: davinci_cpdma: Add boundary for rx
> >and tx descriptors") introduced a function to check the current
> >allocation state of tx packets. The return value is taken into account
> >to stop the netqork queue on the adapter in case there are no free
> >slots.
> >
> >However, cpdma_check_free_tx_desc() returns 'true' if there is room in
> >the bitmap, not 'false', so the usage of the function is wrong.
> >
> >Signed-off-by: Daniel Mack <zonque@...il.com>
> >Cc: Mugunthan V N <mugunthanvnm@...com>
> >Reported-by: Sven Neumann <s.neumann@...mfeld.com>
> >Reported-by: Andreas Fenkart <andreas.fenkart@...eamunlimited.com>
> >---
> >  drivers/net/ethernet/ti/cpsw.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/drivers/net/ethernet/ti/cpsw.c b/drivers/net/ethernet/ti/cpsw.c
> >index 01ffbc4..75c4855 100644
> >--- a/drivers/net/ethernet/ti/cpsw.c
> >+++ b/drivers/net/ethernet/ti/cpsw.c
> >@@ -905,7 +905,7 @@ static netdev_tx_t cpsw_ndo_start_xmit(struct sk_buff *skb,
> >  	/* If there is no more tx desc left free then we need to
> >  	 * tell the kernel to stop sending us tx frames.
> >  	 */
> >-	if (unlikely(cpdma_check_free_tx_desc(priv->txch)))
> >+	if (unlikely(!cpdma_check_free_tx_desc(priv->txch)))
> >  		netif_stop_queue(ndev);
> >  	return NETDEV_TX_OK;
> Tested-by: Mugunthan V N <mugunthanvnm@...com>
> Acked-by: Mugunthan V N <mugunthanvnm@...com>
> 
> Regards
> Mugunthan V N

This restores throughput to the level of 3.7.0

Tested-by: Andreas Fenkart <andreas.fenkart@...eamunlimited.com>

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