| Message ID | 20230426211607.2054776-1-tong.ho@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | hw/nvram: Avoid unnecessary Xilinx eFuse backstore write | expand |
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 > >
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 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 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
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; }
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(-)