Flushing L3 cache may need variable time depending upon cache line
allocation.
Coming up with a proper timeout value would be best handled by
simulations under multiple scenarios in your actual system.
From the purely HN-F point of view, the flush would take ~15 cycles for
a clean line, and ~22 cycles for a dirty line. For the dirty line case,
there are many variables outside the HN-F that will increase the
duration per line. For example, a *DBIDResp from the SN-F/SBSX,
memory controller latency, SN-F/SBSX RetryAck responses, CCN ring
congestion, CCN ring hops, etc, etc. The worst-case timeout would
have to factor in all of these variables plus the HN-F cycles for
every line in the L3, and assuming all lines are dirty
In case if L3 is not flushed properly, system behaviour will be
erratic, so remove timeout and add loop to check status of L3 cache.
System will stuck in while loop if there is some issue in L3 cache
flushing.
Signed-off-by: Udit Kumar
Signed-off-by: Meenakshi Aggarwal
---
changed for v2:
- An increase in timeout doesn't ensure completion of
L3 cache flushing operation. So checking the L3 cache
status till it succedd.
changed for v3:
- Updated Copyright
- add loop to poll for l3 dcache status in hnf_pstate_poll
function
- removed timeout related code as it is not needed
---
arch/arm/cpu/armv8/fsl-layerscape/lowlevel.S | 30
1 file changed, 8 insertions(+), 22 deletions(-)
diff --git a/arch/arm/cpu/armv8/fsl-layerscape/lowlevel.S
b/arch/arm/cpu/armv8/fsl-layerscape/lowlevel.S
index 6721a57..711ab87 100644
--- a/arch/arm/cpu/armv8/fsl-layerscape/lowlevel.S
+++ b/arch/arm/cpu/armv8/fsl-layerscape/lowlevel.S
@@ -1,6 +1,7 @@
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* (C) Copyright 2014-2015 Freescale Semiconductor
+ * Copyright 2019 NXP
*
* Extracted from armv8/start.S
*/
@@ -356,31 +357,22 @@ get_svr:
#if defined(CONFIG_SYS_FSL_HAS_CCN504) || defined(CONFIG_SYS_FSL_HAS_CCN508)
hnf_pstate_poll:
- /* x0 has the desired status, return 0 for success, 1 for timeout
-* clobber x1, x2, x3, x4, x6, x7
+ /* x0 has the desired status, return only if operation succeed
+* clobber x1, x2, x6
*/
mov x1, x0
- mov x7, #0 /* flag for timeout */
- mrs x3, cntpct_el0 /* read timer */
- add x3, x3, #1200 /* timeout after 100 microseconds */
+ mov w6, #8 /* HN-F node count */
mov x0, #0x18
movkx0, #0x420, lsl #16 /* HNF0_PSTATE_STATUS */
- mov w6, #8 /* HN-F node count */
1:
ldr x2, [x0]
cmp x2, x1 /* check status */
b.eq2f
- mrs x4, cntpct_el0
- cmp x4, x3
- b.ls1b
- mov x7, #1 /* timeout */
- b 3f
+ b 1b
2:
add x0, x0, #0x1/* move to next node */
subsw6, w6, #1
cbnzw6, 1b
-3:
- mov x0, x7
ret
hnf_set_pstate:
@@ -405,10 +397,8 @@ ENTRY(__asm_flush_l3_dcache)
/*
* Return status in x0
*success 0
-*timeout 1 for setting SFONLY, 2 for FAM, 3 for both
*/
mov x29, lr
- mov x8, #0
dsb sy
mov x0, #0x1/* HNFPSTAT_SFONLY */
@@ -416,19 +406,15 @@ ENTRY(__asm_flush_l3_dcache)
mov x0, #0x4/* SFONLY status */
bl hnf_pstate_poll
- cbz x0, 1f
- mov x8, #1 /* timeout */
-1:
+
dsb sy
mov x0, #0x3/* HNFPSTAT_FAM */
bl hnf_set_pstate
mov x0, #0xc/* FAM status */
bl hnf_pstate_poll
- cbz x0, 1f
- add x8, x8, #0x2
-1:
- mov x0, x8
+
+ mov x0, #0
mov lr, x29
ret
ENDPROC(__asm_flush_l3_dcache)
--
1.9.1
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