[U-Boot] [PATCH] imx6: cache: disable L2 before touching Auxiliary Control Register

[Peng Fan]

From: Peng Fan <peng.fan at nxp.com>

According PL310 TRM, Auxiliary Control Register
"
The register must be written to using a secure access, and it can be
read using either a secure or a NS access. If you write to this register
with a NS access, it results in a write response with a DECERR response,
and the register is not updated. Writing to this register with the L2
cache enabled, that is, bit[0] of L2 Control Register set to 1,
results in a SLVERR.
"

So If L2 cache is already enabled by ROM, chaning value of ACR
will cause SLVERR and uboot hang.

Signed-off-by: Peng Fan <peng.fan at nxp.com>
Cc: Stefano Babic <sbabic at denx.de>
Cc: Fabio Estevam <fabio.estevam at nxp.com>
---
 arch/arm/imx-common/cache.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/arm/imx-common/cache.c b/arch/arm/imx-common/cache.c
index 54b021c..b775488 100644
--- a/arch/arm/imx-common/cache.c
+++ b/arch/arm/imx-common/cache.c
@@ -43,6 +43,12 @@ void v7_outer_cache_enable(void)
 
 
 	/*
+	 * Must disable the L2 before changing the latency parameters
+	 * and auxiliary control register.
+	 */
+	clrbits_le32(&pl310->pl310_ctrl, L2X0_CTRL_EN);
+
+	/*
 	 * Set bit 22 in the auxiliary control register. If this bit
 	 * is cleared, PL310 treats Normal Shared Non-cacheable
 	 * accesses as Cacheable no-allocate.
@@ -59,9 +65,6 @@ void v7_outer_cache_enable(void)
 	}
 #endif
 
-	/* Must disable the L2 before changing the latency parameters */
-	clrbits_le32(&pl310->pl310_ctrl, L2X0_CTRL_EN);
-
 	writel(0x132, &pl310->pl310_tag_latency_ctrl);
 	writel(0x132, &pl310->pl310_data_latency_ctrl);
 
-- 
2.6.2