From: Mike Sinkovsky <msink@permonline•ru>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: netdev@vger•kernel.org, linux-kernel@vger•kernel.org
Subject: Re: [PATCH v6 0/2] Ethernet drivers for WIZnet chips
Date: Wed, 04 Apr 2012 11:58:35 +0600 [thread overview]
Message-ID: <4F7BE30B.9020603@permonline.ru> (raw)
In-Reply-To: <1333456156.18626.93.camel@edumazet-glaptop>
03.04.2012 18:29, Eric Dumazet написал:
> On Tue, 2012-04-03 at 18:15 +0600, Mike Sinkovsky wrote:
>> 03.04.2012 17:39, Eric Dumazet написал:
>>> On Tue, 2012-04-03 at 16:58 +0600, Mike Sinkovsky wrote:
>>>> Based on original driver from chip manufacturer, but nearly full rewite.
>>>> Tested and used in production with Blackfin BF531 embedded processor.
>>>>
>>>> Signed-off-by: Mike Sinkovsky<msink@permonline•ru>
>>>> ---
>>>> v6:
>>>> - remove (S0_TX_FSR< skb->len) check in TX handler, it doesn't work
>>>> anyway. Chip can transmit only one frame with MTU 1500 at a time,
>>>> and tx buffer size is bigger.
>>>
>>> So what happens if XXX frames are given to start_xmit() in a flood ?
>>>
>>> You removed any flow control, how can this work ?
>>>
>>> Device has an infinite queue ?
>>
>> As I understand from datasheet, device doesn't have tx queue at all.
>> It have tx buffer, processor must save transmitted frame to it, and then
>> save SEND command to command register. When transmission completed,
>> SENDOK bit in interrupt register will be set to '1', and interrupt
>> handler will be called.
>>
>> So, according to datasheet, driver must stop queue in start_xmit()
>> routine, and wake in interrupt handler of SENDOK bit.
>> I tried this, and it basically works, but SOMETIMES, very rare, I see
>> tx_timeout().
>>
>> And without any flow control - driver works perfectly.
>> Weird, don't know why.
>
> Really this should be fixed, since your driver makes qdisc flow control
> impossible (unless adding a rate limiter like HTB/CBQ)
>
> You probably had a race on your xmit routine, and interrupt routine.
>
> You need proper synchronization : A spinlock to make this easy, or a
> smart barrier game.
I can at least make it configurable from Kconfig with default 'y', and
disable for our boards.
Would it be acceptable?
About races - I can't see any, in this very simple procedure.
But maybe I missed something..
--
Mike
next prev parent reply other threads:[~2012-04-04 5:58 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-19 9:23 [PATCH v2] ethernet driver for the WIZnet W5300 chip Mike Sinkovsky
2012-03-20 18:08 ` Ben Hutchings
2012-03-21 6:20 ` Mike Sinkovsky
2012-03-22 16:57 ` Ben Hutchings
2012-03-21 14:49 ` Florian Fainelli
2012-03-22 6:58 ` Mike Sinkovsky
2012-03-24 11:02 ` [PATCH v3] Ethernet " Mike Sinkovsky
2012-03-24 15:53 ` Joe Perches
2012-03-24 16:10 ` Eric Dumazet
2012-03-26 9:05 ` Mike Sinkovsky
2012-03-26 9:07 ` [PATCH v4] " Mike Sinkovsky
2012-03-28 2:35 ` David Miller
2012-03-28 5:52 ` Mike Sinkovsky
2012-03-28 6:22 ` David Miller
2012-03-30 7:00 ` [PATCH v5 1/2] " Mike Sinkovsky
2012-03-31 21:45 ` Mark Brown
2012-03-30 7:00 ` [PATCH v5 2/2] Ethernet driver for the WIZnet W5100 chip Mike Sinkovsky
2012-03-30 9:23 ` Eric Dumazet
2012-03-31 9:40 ` Francois Romieu
2012-03-31 9:46 ` Francois Romieu
2012-03-31 9:52 ` Mike Sinkovsky
2012-03-31 10:24 ` Eric Dumazet
2012-03-31 21:23 ` Mark Brown
2012-04-02 9:40 ` Mike Sinkovsky
2012-04-02 11:21 ` Mark Brown
2012-04-03 10:58 ` [PATCH v6 0/2] Ethernet drivers for WIZnet chips Mike Sinkovsky
2012-04-03 11:39 ` Eric Dumazet
2012-04-03 12:15 ` Mike Sinkovsky
2012-04-03 12:29 ` Eric Dumazet
2012-04-04 5:58 ` Mike Sinkovsky [this message]
2012-04-04 6:17 ` Eric Dumazet
2012-04-04 7:25 ` Mike Sinkovsky
2012-04-04 7:23 ` [PATCH v7 " Mike Sinkovsky
2012-04-04 11:57 ` [PATCH v8 " Mike Sinkovsky
2012-04-05 1:15 ` David Miller
2012-04-05 5:36 ` Mike Sinkovsky
2012-04-04 11:57 ` [PATCH v8 1/2] Ethernet driver for the WIZnet W5300 chip Mike Sinkovsky
2012-04-04 11:57 ` [PATCH v8 2/2] Ethernet driver for the WIZnet W5100 chip Mike Sinkovsky
2012-04-04 12:08 ` [PATCH v8 0/2] Ethernet drivers for WIZnet chips Mike Sinkovsky
2012-04-05 5:33 ` [PATCH v9 " Mike Sinkovsky
2012-04-05 5:47 ` David Miller
2012-04-05 5:33 ` [PATCH v9 1/2] Ethernet driver for the WIZnet W5300 chip Mike Sinkovsky
2012-04-05 5:33 ` [PATCH v9 2/2] Ethernet driver for the WIZnet W5100 chip Mike Sinkovsky
2012-04-04 12:08 ` [PATCH v8 1/2] Ethernet driver for the WIZnet W5300 chip Mike Sinkovsky
2012-04-04 12:08 ` [PATCH v8 2/2] Ethernet driver for the WIZnet W5100 chip Mike Sinkovsky
2012-04-04 7:23 ` [PATCH v7 1/2] Ethernet driver for the WIZnet W5300 chip Mike Sinkovsky
2012-04-04 7:23 ` [PATCH v7 2/2] Ethernet driver for the WIZnet W5100 chip Mike Sinkovsky
2012-04-03 10:58 ` [PATCH v6 1/2] Ethernet driver for the WIZnet W5300 chip Mike Sinkovsky
2012-04-03 13:36 ` Mark Brown
2012-04-04 6:18 ` Mike Sinkovsky
2012-04-04 10:01 ` Mark Brown
2012-04-04 11:00 ` Mike Sinkovsky
2012-04-03 10:58 ` [PATCH v6 2/2] Ethernet driver for the WIZnet W5100 chip Mike Sinkovsky
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