hw/nvram/xlnx-efuse.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
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
On Wed, 26 Apr 2023 at 22:16, Tong Ho <tong.ho@amd.com> wrote: > > 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> > --- Applied to target-arm.next, thanks. -- PMM
On 26/4/23 23:16, Tong Ho wrote: > 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(-) Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
On [2023 Apr 26] Wed 14:16:07, Tong Ho wrote: > 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> Reviewed-by: Francisco Iglesias <frasse.iglesias@gmail.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 >
On Thu, Apr 27, 2023 at 10:31 AM Tong Ho <tong.ho@amd.com> wrote: > > 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> Reviewed-by: Alistair Francis <alistair.francis@wdc.com> Alistair > --- > 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 > >
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