[PATCH] Revert "net: stmmac: re-init rx buffers when mac resume back"

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

This reverts commit 9c63faaa931e443e7abbbee9de0169f1d4710546, which
introduces a suspend/resume regression on Jetson TX2 boards that can be
reproduced every time. Given that the issue that this was supposed to
fix only occurs very sporadically the safest course of action is to
revert before v5.12 and then we can have another go at fixing the more
rare issue in the next release (and perhaps backport it if necessary).

The root cause of the observed problem seems to be that when the system
is suspended, some packets are still in transit. When the descriptors
for these buffers are cleared on resume, the descriptors become invalid
and cause a fatal bus error.

Link: https://lore.kernel.org/r/708edb92-a5df-ecc4-3126-5ab36707e275@nvidia.com/
Reported-by: Jonathan Hunter <jonathanh@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
David, Jakub,

I noticed that a couple of patches got merged on top of this in
net-next, so the revert is going to cause conflicts. However, I've based
this revert on v5.12-rc7 because it targets v5.12. Let me know if I can
help resolve the conflict with net-next.

Thierry

 .../net/ethernet/stmicro/stmmac/stmmac_main.c | 84 +------------------
 1 file changed, 1 insertion(+), 83 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 208cae344ffa..4749bd0af160 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -1379,88 +1379,6 @@ static void stmmac_free_tx_buffer(struct stmmac_priv *priv, u32 queue, int i)
 	}
 }
 
-/**
- * stmmac_reinit_rx_buffers - reinit the RX descriptor buffer.
- * @priv: driver private structure
- * Description: this function is called to re-allocate a receive buffer, perform
- * the DMA mapping and init the descriptor.
- */
-static void stmmac_reinit_rx_buffers(struct stmmac_priv *priv)
-{
-	u32 rx_count = priv->plat->rx_queues_to_use;
-	u32 queue;
-	int i;
-
-	for (queue = 0; queue < rx_count; queue++) {
-		struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
-
-		for (i = 0; i < priv->dma_rx_size; i++) {
-			struct stmmac_rx_buffer *buf = &rx_q->buf_pool[i];
-
-			if (buf->page) {
-				page_pool_recycle_direct(rx_q->page_pool, buf->page);
-				buf->page = NULL;
-			}
-
-			if (priv->sph && buf->sec_page) {
-				page_pool_recycle_direct(rx_q->page_pool, buf->sec_page);
-				buf->sec_page = NULL;
-			}
-		}
-	}
-
-	for (queue = 0; queue < rx_count; queue++) {
-		struct stmmac_rx_queue *rx_q = &priv->rx_queue[queue];
-
-		for (i = 0; i < priv->dma_rx_size; i++) {
-			struct stmmac_rx_buffer *buf = &rx_q->buf_pool[i];
-			struct dma_desc *p;
-
-			if (priv->extend_desc)
-				p = &((rx_q->dma_erx + i)->basic);
-			else
-				p = rx_q->dma_rx + i;
-
-			if (!buf->page) {
-				buf->page = page_pool_dev_alloc_pages(rx_q->page_pool);
-				if (!buf->page)
-					goto err_reinit_rx_buffers;
-
-				buf->addr = page_pool_get_dma_addr(buf->page);
-			}
-
-			if (priv->sph && !buf->sec_page) {
-				buf->sec_page = page_pool_dev_alloc_pages(rx_q->page_pool);
-				if (!buf->sec_page)
-					goto err_reinit_rx_buffers;
-
-				buf->sec_addr = page_pool_get_dma_addr(buf->sec_page);
-			}
-
-			stmmac_set_desc_addr(priv, p, buf->addr);
-			if (priv->sph)
-				stmmac_set_desc_sec_addr(priv, p, buf->sec_addr, true);
-			else
-				stmmac_set_desc_sec_addr(priv, p, buf->sec_addr, false);
-			if (priv->dma_buf_sz == BUF_SIZE_16KiB)
-				stmmac_init_desc3(priv, p);
-		}
-	}
-
-	return;
-
-err_reinit_rx_buffers:
-	do {
-		while (--i >= 0)
-			stmmac_free_rx_buffer(priv, queue, i);
-
-		if (queue == 0)
-			break;
-
-		i = priv->dma_rx_size;
-	} while (queue-- > 0);
-}
-
 /**
  * init_dma_rx_desc_rings - init the RX descriptor rings
  * @dev: net device structure
@@ -5428,7 +5346,7 @@ int stmmac_resume(struct device *dev)
 	mutex_lock(&priv->lock);
 
 	stmmac_reset_queues_param(priv);
-	stmmac_reinit_rx_buffers(priv);
+
 	stmmac_free_tx_skbufs(priv);
 	stmmac_clear_descriptors(priv);
 
-- 
2.30.2