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[PATCH] hw/nvram: Avoid unnecessary Xilinx eFuse backstore write
From: |
Tong Ho |
Subject: |
[PATCH] hw/nvram: Avoid unnecessary Xilinx eFuse backstore write |
Date: |
Wed, 26 Apr 2023 14:16:07 -0700 |
Add a check in the bit-set operation to write the backstore
only if the affected bit is 0 before.
With this in place, there will be no need for callers to
do the checking in order to avoid unnecessary writes.
Signed-off-by: Tong Ho <tong.ho@amd.com>
---
hw/nvram/xlnx-efuse.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/hw/nvram/xlnx-efuse.c b/hw/nvram/xlnx-efuse.c
index fdfffaab99..655c40b8d1 100644
--- a/hw/nvram/xlnx-efuse.c
+++ b/hw/nvram/xlnx-efuse.c
@@ -143,6 +143,8 @@ static bool efuse_ro_bits_find(XlnxEFuse *s, uint32_t k)
bool xlnx_efuse_set_bit(XlnxEFuse *s, unsigned int bit)
{
+ uint32_t set, *row;
+
if (efuse_ro_bits_find(s, bit)) {
g_autofree char *path = object_get_canonical_path(OBJECT(s));
@@ -152,8 +154,13 @@ bool xlnx_efuse_set_bit(XlnxEFuse *s, unsigned int bit)
return false;
}
- s->fuse32[bit / 32] |= 1 << (bit % 32);
- efuse_bdrv_sync(s, bit);
+ /* Avoid back-end write unless there is a real update */
+ row = &s->fuse32[bit / 32];
+ set = 1 << (bit % 32);
+ if (!(set & *row)) {
+ *row |= set;
+ efuse_bdrv_sync(s, bit);
+ }
return true;
}
--
2.25.1
- [PATCH] hw/nvram: Avoid unnecessary Xilinx eFuse backstore write,
Tong Ho <=