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

[Jose Abreu <Jose.Abreu@synopsys.com>]

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

> From: Jon Hunter <jonathanh@nvidia.com>
> Date: Jul/26/2019, 15:11:00 (UTC+00:00)
> 
> > 
> > On 25/07/2019 16:12, Jose Abreu wrote:
> > > From: Jon Hunter <jonathanh@nvidia.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

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From d203a4f055a36ae20efbcee7cdf70ce13fff12c9 Mon Sep 17 00:00:00 2001
Message-Id: <d203a4f055a36ae20efbcee7cdf70ce13fff12c9.1564388075.git.joabreu@synopsys.com>
From: Jose Abreu <joabreu@synopsys.com>
Date: Mon, 29 Jul 2019 10:14:21 +0200
Subject: [PATCH net] net: page_pool: Do not skip CPU sync

Signed-off-by: Jose Abreu <joabreu@synopsys.com>
---
Cc: Jesper Dangaard Brouer <hawk@kernel.org>
Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 net/core/page_pool.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/core/page_pool.c b/net/core/page_pool.c
index 3272dc7a8c81..0262fcdf217e 100644
--- a/net/core/page_pool.c
+++ b/net/core/page_pool.c
@@ -156,7 +156,7 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
 	 */
 	dma = dma_map_page_attrs(pool->p.dev, page, 0,
 				 (PAGE_SIZE << pool->p.order),
-				 pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
+				 pool->p.dma_dir, 0);
 	if (dma_mapping_error(pool->p.dev, dma)) {
 		put_page(page);
 		return NULL;
@@ -230,8 +230,7 @@ static void __page_pool_clean_page(struct page_pool *pool,
 	dma = page->dma_addr;
 	/* DMA unmap */
 	dma_unmap_page_attrs(pool->p.dev, dma,
-			     PAGE_SIZE << pool->p.order, pool->p.dma_dir,
-			     DMA_ATTR_SKIP_CPU_SYNC);
+			     PAGE_SIZE << pool->p.order, pool->p.dma_dir, 0);
 	page->dma_addr = 0;
 skip_dma_unmap:
 	atomic_inc(&pool->pages_state_release_cnt);
-- 
2.7.4