netdev - [PATCH net 3/3] net: ipa: use state to determine event ring command success

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Date:   Tue, 22 Dec 2020 12:00:12 -0600
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     evgreen@...omium.org, cpratapa@...eaurora.org,
        bjorn.andersson@...aro.org, subashab@...eaurora.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net 3/3] net: ipa: use state to determine event ring command success

This patch implements the same basic fix for event rings as the
previous one does for channels.

The result of issuing an event ring control command should be that
the event ring changes state.  If enabled, a completion interrupt
signals that the event ring state has changed.  This interrupt is
enabled by gsi_evt_ring_command() and disabled again after the
command has completed (or we time out).

There is a window of time during which the command could complete
successfully without interrupting.  This would cause the event ring
to transition to the desired new state.

So whether a event ring command ends via completion interrupt or
timeout, we can consider the command successful if the event ring
has entered the desired state (and a failure if it has not,
regardless of the cause).

Fixes: b4175f8731f78 ("net: ipa: only enable GSI event control IRQs when needed")
Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/gsi.c | 34 ++++++++++++++++++++++------------
 1 file changed, 22 insertions(+), 12 deletions(-)

diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index 4f0e791764237..579cc3e516775 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -384,13 +384,15 @@ static int gsi_evt_ring_alloc_command(struct gsi *gsi, u32 evt_ring_id)
 	}
 
 	ret = evt_ring_command(gsi, evt_ring_id, GSI_EVT_ALLOCATE);
-	if (!ret && evt_ring->state != GSI_EVT_RING_STATE_ALLOCATED) {
-		dev_err(gsi->dev, "event ring %u bad state %u after alloc\n",
-			evt_ring_id, evt_ring->state);
-		ret = -EIO;
-	}
 
-	return ret;
+	/* If successful the event ring state will have changed */
+	if (evt_ring->state == GSI_EVT_RING_STATE_ALLOCATED)
+		return 0;
+
+	dev_err(gsi->dev, "event ring %u bad state %u after alloc\n",
+		evt_ring_id, evt_ring->state);
+
+	return -EIO;
 }
 
 /* Reset a GSI event ring in ALLOCATED or ERROR state. */
@@ -408,9 +410,13 @@ static void gsi_evt_ring_reset_command(struct gsi *gsi, u32 evt_ring_id)
 	}
 
 	ret = evt_ring_command(gsi, evt_ring_id, GSI_EVT_RESET);
-	if (!ret && evt_ring->state != GSI_EVT_RING_STATE_ALLOCATED)
-		dev_err(gsi->dev, "event ring %u bad state %u after reset\n",
-			evt_ring_id, evt_ring->state);
+
+	/* If successful the event ring state will have changed */
+	if (evt_ring->state == GSI_EVT_RING_STATE_ALLOCATED)
+		return;
+
+	dev_err(gsi->dev, "event ring %u bad state %u after reset\n",
+		evt_ring_id, evt_ring->state);
 }
 
 /* Issue a hardware de-allocation request for an allocated event ring */
@@ -426,9 +432,13 @@ static void gsi_evt_ring_de_alloc_command(struct gsi *gsi, u32 evt_ring_id)
 	}
 
 	ret = evt_ring_command(gsi, evt_ring_id, GSI_EVT_DE_ALLOC);
-	if (!ret && evt_ring->state != GSI_EVT_RING_STATE_NOT_ALLOCATED)
-		dev_err(gsi->dev, "event ring %u bad state %u after dealloc\n",
-			evt_ring_id, evt_ring->state);
+
+	/* If successful the event ring state will have changed */
+	if (evt_ring->state == GSI_EVT_RING_STATE_NOT_ALLOCATED)
+		return;
+
+	dev_err(gsi->dev, "event ring %u bad state %u after dealloc\n",
+		evt_ring_id, evt_ring->state);
 }
 
 /* Fetch the current state of a channel from hardware */
-- 
2.20.1