netdev - Re: [PATCH] [v6] net: emac: emac gigabit ethernet controller driver

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Date:	Wed, 3 Aug 2016 15:00:34 -0500
From:	Timur Tabi <timur@...eaurora.org>
To:	Lino Sanfilippo <LinoSanfilippo@....de>, netdev@...r.kernel.org,
	devicetree@...r.kernel.org, linux-arm-msm@...r.kernel.org,
	sdharia@...eaurora.org, shankerd@...eaurora.org,
	vikrams@...eaurora.org, cov@...eaurora.org, gavidov@...eaurora.org,
	robh+dt@...nel.org, andrew@...n.ch, bjorn.andersson@...aro.org,
	mlangsdo@...hat.com, jcm@...hat.com, agross@...eaurora.org,
	davem@...emloft.net, f.fainelli@...il.com
Subject: Re: [PATCH] [v6] net: emac: emac gigabit ethernet controller driver

Timur Tabi wrote:
>
> Is there a good way to test my code? ping and iperf appear to send no
> more than 3 packets at a time, which comes nowhere close to filling the
> queue (which holds 512 normally).  netif_queue_stopped() never returns
> true, no matter what I do.

Never mind, I fixed this problem.  I had a race condition between

	/* update produce idx */
	prod_idx = (tx_q->tpd.produce_idx << tx_q->produce_shift) &
		    tx_q->produce_mask;
	emac_reg_update32(adpt->base + tx_q->produce_reg,
			  tx_q->produce_mask, prod_idx);

and the call to netif_stop_queue().  The emac_reg_update32() signalled 
to the hardware that data is available, and it immediately called the 
ISR, before I had a chance to call netif_stop_queue().  So now I call 
emac_reg_update32() after netif_stop_queue(), and everything works.

I'll post a v7 soon.

-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm
Technologies, Inc.  Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.