linux-kernel - RE: [PATCH net-next 3/3] net: stmmac: Introducing support for Page Pool

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Message-ID: <MN2PR12MB327907D4A6FB378AC989571AD3DD0@MN2PR12MB3279.namprd12.prod.outlook.com>
Date:   Mon, 29 Jul 2019 08:16:15 +0000
From:   Jose Abreu <Jose.Abreu@...opsys.com>
To:     Jon Hunter <jonathanh@...dia.com>,
        Jose Abreu <Jose.Abreu@...opsys.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
CC:     Joao Pinto <Joao.Pinto@...opsys.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Ripard <maxime.ripard@...tlin.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Giuseppe Cavallaro <peppe.cavallaro@...com>,
        Robin Murphy <robin.murphy@....com>,
        "David S . Miller" <davem@...emloft.net>
Subject: RE: [PATCH net-next 3/3] net: stmmac: Introducing support for Page
 Pool

From: Jose Abreu <joabreu@...opsys.com>
Date: Jul/27/2019, 16:56:37 (UTC+00:00)

> From: Jon Hunter <jonathanh@...dia.com>
> Date: Jul/26/2019, 15:11:00 (UTC+00:00)
> 
> > 
> > On 25/07/2019 16:12, Jose Abreu wrote:
> > > From: Jon Hunter <jonathanh@...dia.com>
> > > Date: Jul/25/2019, 15:25:59 (UTC+00:00)
> > > 
> > >>
> > >> On 25/07/2019 14:26, Jose Abreu wrote:
> > >>
> > >> ...
> > >>
> > >>> Well, I wasn't expecting that :/
> > >>>
> > >>> Per documentation of barriers I think we should set descriptor fields 
> > >>> and then barrier and finally ownership to HW so that remaining fields 
> > >>> are coherent before owner is set.
> > >>>
> > >>> Anyway, can you also add a dma_rmb() after the call to 
> > >>> stmmac_rx_status() ?
> > >>
> > >> Yes. I removed the debug print added the barrier, but that did not help.
> > > 
> > > So, I was finally able to setup NFS using your replicated setup and I 
> > > can't see the issue :(
> > > 
> > > The only difference I have from yours is that I'm using TCP in NFS 
> > > whilst you (I believe from the logs), use UDP.
> > 
> > So I tried TCP by setting the kernel boot params to 'nfsvers=3' and
> > 'proto=tcp' and this does appear to be more stable, but not 100% stable.
> > It still appears to fail in the same place about 50% of the time.
> > 
> > > You do have flow control active right ? And your HW FIFO size is >= 4k ?
> > 
> > How can I verify if flow control is active?
> 
> You can check it by dumping register MTL_RxQ_Operation_Mode (0xd30).
> 
> Can you also add IOMMU debug in file "drivers/iommu/iommu.c" ?

And, please try attached debug patch.

---
Thanks,
Jose Miguel Abreu

Download attachment "0001-net-page_pool-Do-not-skip-CPU-sync.patch" of type "application/octet-stream" (1532 bytes)