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	Patches adding DSA support for MT7988 have been backported to Linux 5.15 but not to Linux 6.1. Import backports also to Linux 6.1. Signed-off-by: Daniel Golle <daniel@makrotopia.org>
		
			
				
	
	
		
			48 lines
		
	
	
		
			1.6 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			48 lines
		
	
	
		
			1.6 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
From a52cadbf76593f8fcb2f4f62cb006e3f2a22ad06 Mon Sep 17 00:00:00 2001
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From: Daniel Golle <daniel@makrotopia.org>
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Date: Mon, 3 Apr 2023 02:19:28 +0100
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Subject: [PATCH 11/13] net: dsa: mt7530: skip locking if MDIO bus isn't
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 present
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As MT7530 and MT7531 internally use 32-bit wide registers, each access
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to any register of the switch requires several operations on the MDIO
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bus. Hence if there is congruent access, e.g. due to PCS or PHY
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polling, this can mess up and interfere with another ongoing register
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access sequence.
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However, the MDIO bus mutex is only relevant for MDIO-connected
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switches. Prepare switches which have there registers directly mapped
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into the SoCs register space via MMIO which do not require such
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locking. There we can simply use regmap's default locking mechanism.
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Hence guard mutex operations to only be performed in case of MDIO
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connected switches.
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Signed-off-by: Daniel Golle <daniel@makrotopia.org>
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Reviewed-by: Andrew Lunn <andrew@lunn.ch>
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Signed-off-by: David S. Miller <davem@davemloft.net>
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---
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 drivers/net/dsa/mt7530.c | 6 ++++--
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 1 file changed, 4 insertions(+), 2 deletions(-)
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--- a/drivers/net/dsa/mt7530.c
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+++ b/drivers/net/dsa/mt7530.c
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@@ -144,13 +144,15 @@ err:
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 static void
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 mt7530_mutex_lock(struct mt7530_priv *priv)
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 {
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-	mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
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+	if (priv->bus)
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+		mutex_lock_nested(&priv->bus->mdio_lock, MDIO_MUTEX_NESTED);
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 }
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 static void
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 mt7530_mutex_unlock(struct mt7530_priv *priv)
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 {
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-	mutex_unlock(&priv->bus->mdio_lock);
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+	if (priv->bus)
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+		mutex_unlock(&priv->bus->mdio_lock);
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 }
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 static void
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