[U-Boot] [PATCH 1/2 V4] arm926: Flush the data cache before disabling it

Sughosh Ganu
2012-01-14T14:02:59Z

The current implementation invalidates the cache instead of flushing
it. This causes problems on platforms where the spl/u-boot is already
loaded to the RAM, with caches enabled by a first stage bootloader.

Also fix the comments to match code.

Signed-off-by: Sughosh Ganu <urwithsughosh@gmail.com>
Cc: Albert Aribaud <albert.u.boot@aribaud.net>
Cc: Tom Rini <trini@ti.com>
---

Changes since V3
* Removed tampering of the V bit setting. Would be done in a separate
patch on the lines of review comments by Albert.

Changes since V2
* Added code to invalidate I cache, based on review comment by Aneesh.
* Fixed comments to match the code.

Changes since V1
* Added arm926 keyword to the subject line
* Removed the superfluous setting of r0.
* Fixed the comment to reflect the fact that V is not being cleared

arch/arm/cpu/arm926ejs/start.S | 12 ++++++++----
1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S
index 6a09c02..d64165a 100644
--- a/arch/arm/cpu/arm926ejs/start.S
+++ b/arch/arm/cpu/arm926ejs/start.S
@@ -355,14 +355,18 @@ _dynsym_start_ofs:
*/
cpu_init_crit:
/*
- * flush v4 I/D caches
+ * flush D cache before disabling it
*/
mov r0, #0
- mcr p15, 0, r0, c7, c7, 0 /* flush v3/v4 cache */
- mcr p15, 0, r0, c8, c7, 0 /* flush v4 TLB */
+flush_dcache:
+ mrc p15, 0, r15, c7, c10, 3
+ bne flush_dcache
+
+ mcr p15, 0, r0, c8, c7, 0 /* invalidate TLB */
+ mcr p15, 0, r0, c7, c5, 0 /* invalidate I Cache */

/*
- * disable MMU stuff and caches
+ * disable MMU and D cache, and enable I cache.
*/
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002300 /* clear bits 13, 9:8 (--V- --RS) */
--
1.7.5.4