From: Nicolas Ferre <nicolas.ferre@atmel•com>
To: Steffen Trumtrar <s.trumtrar@pengutronix•de>,
Hein Tibosch <hein_tibosch@yahoo•es>, <netdev@vger•kernel.org>,
David Miller <davem@davemloft•net>
Cc: Ludovic Desroches <ludovic.desroches@atmel•com>
Subject: Re: net/macb: clear tx/rx completion flags in ISR
Date: Fri, 19 Apr 2013 09:48:43 +0200 [thread overview]
Message-ID: <5170F6DB.6030500@atmel.com> (raw)
In-Reply-To: <20130419073058.GA660@pengutronix.de>
On 04/19/2013 09:30 AM, Steffen Trumtrar :
> Hi Hein,
>
> On Fri, Apr 19, 2013 at 01:13:26PM +0800, Hein Tibosch wrote:
>> Hi Steffen,
>>
>>> At least in the cadence IP core on the Xilinx Zynq SoC the TCOMP/RCOMP flags
>>> are not auto-cleaned. As these flags are evaluated, they need to be cleaned.
>>
>> This patch does not work for at least the AVR32 platform. Both RCOMP/RCOMP
>> are cleared by *reading* the ISR and writing them would be fatal.
>>
>
> :-(
>
>> Could you tell me the version of the macb of Xilinx Zynq?
>>
>> u32 version = (macb_readl(bp, MID) & ((1 << MACB_REV_SIZE) - 1))
>> | MACB_GREGS_VERSION;
>>
>> On an AP7000 it reads as 0x0000010D
>>
>
> This gives me 0x00000119. The TRM says it is version r1p23.
>
>> I am thinking of making a patch like:
>>
>> if (bp->version >= xxx)
>> macb_writel(bp, ISR, MACB_BIT(TCOMP));
>>
>> if (bp->version >= xxx)
>> macb_writel(bp, ISR, MACB_BIT(RCOMP));
>>
>> which would make it work on both platforms.
Well, keep in mind that it is the hot path: It can harm the performance
if too much tests are performed...
> The documentation I have is a little bit confusing in that regard.
> The cadence datasheet says, this register is R/W, the Xilinx datasheet says,
> it is "normaly RO", but the programming guide explicitely mentions clearing
> the bit by writing to it.
> It seems, that something like your patch is inevitable.
I also had bad feedbacks concerning this patch. Maybe we should take
more time to validate this change: event it is in net-next, maybe we
should revert it for the moment...
Best regards,
--
Nicolas Ferre
next prev parent reply other threads:[~2013-04-19 7:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-19 5:13 net/macb: clear tx/rx completion flags in ISR Hein Tibosch
2013-04-19 7:30 ` Steffen Trumtrar
2013-04-19 7:48 ` Nicolas Ferre [this message]
2013-04-19 9:21 ` Hein Tibosch
2013-04-19 9:38 ` Steffen Trumtrar
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