From: Sean Anderson <seanga2@gmail.com>
To: u-boot@lists.denx.de
Subject: [PATCH v3 5/7] riscv: Consolidate fences into AMOs for available_harts_lock
Date: Mon, 21 Sep 2020 07:51:39 -0400 [thread overview]
Message-ID: <20200921115141.70598-6-seanga2@gmail.com> (raw)
In-Reply-To: <20200921115141.70598-1-seanga2@gmail.com>
We can reduce the number of instructions needed to use available_harts_lock
by using the aq and rl suffixes for AMOs.
Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Rick Chen <rick@andestech.com>
---
(no changes since v2)
Changes in v2:
- Remove fences after amoswaps
- Reword commit message
arch/riscv/cpu/start.S | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)
diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
index e3222b1ea7..66ca1c7020 100644
--- a/arch/riscv/cpu/start.S
+++ b/arch/riscv/cpu/start.S
@@ -125,14 +125,12 @@ call_board_init_f_0:
#ifndef CONFIG_XIP
la t0, available_harts_lock
- fence rw, w
- amoswap.w zero, zero, 0(t0)
+ amoswap.w.rl zero, zero, 0(t0)
wait_for_gd_init:
la t0, available_harts_lock
li t1, 1
-1: amoswap.w t1, t1, 0(t0)
- fence r, rw
+1: amoswap.w.aq t1, t1, 0(t0)
bnez t1, 1b
/* register available harts in the available_harts mask */
@@ -142,8 +140,7 @@ wait_for_gd_init:
or t2, t2, t1
SREG t2, GD_AVAILABLE_HARTS(gp)
- fence rw, w
- amoswap.w zero, zero, 0(t0)
+ amoswap.w.rl zero, zero, 0(t0)
/*
* Continue on hart lottery winner, others branch to
--
2.28.0
next prev parent reply other threads:[~2020-09-21 11:51 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-21 11:51 [PATCH v3 0/7] riscv: Correctly handle IPIs already pending upon boot Sean Anderson
2020-09-21 11:51 ` [PATCH v3 1/7] Revert "riscv: Clear pending interrupts before enabling IPIs" Sean Anderson
2020-09-22 0:56 ` Rick Chen
2020-09-21 11:51 ` [PATCH v3 2/7] riscv: Match memory barriers between send_ipi_many and handle_ipi Sean Anderson
2020-09-21 11:51 ` [PATCH v3 3/7] riscv: Use a valid bit to ignore already-pending IPIs Sean Anderson
2020-09-21 11:51 ` [PATCH v3 4/7] riscv: Clear pending IPIs on initialization Sean Anderson
2020-09-22 0:58 ` Rick Chen
2020-09-21 11:51 ` Sean Anderson [this message]
2020-09-21 11:51 ` [PATCH v3 6/7] riscv: Ensure gp is NULL or points to valid data Sean Anderson
2020-09-22 1:05 ` Rick Chen
2020-09-21 11:51 ` [PATCH v3 7/7] riscv: Add some comments to start.S Sean Anderson
2020-09-21 16:23 ` Heinrich Schuchardt
2020-09-21 16:40 ` Sean Anderson
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