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

Peng Fan
2016-05-04T07:27:50Z

From: Peng Fan <peng.fan@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@nxp.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@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