| Message ID | 20220126231239.1443128-3-tobias@waldekranz.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | net: dsa: mv88e6xxx: Improve indirect addressing performance | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Clearly marked for net-next |
| netdev/fixes_present | success | Fixes tag not required for -next series |
| netdev/subject_prefix | success | Link |
| netdev/cover_letter | success | Series has a cover letter |
| netdev/patch_count | success | Link |
| netdev/header_inline | success | No static functions without inline keyword in header files |
| netdev/build_32bit | success | Errors and warnings before: 0 this patch: 0 |
| netdev/cc_maintainers | success | CCed 7 of 7 maintainers |
| netdev/build_clang | success | Errors and warnings before: 0 this patch: 0 |
| netdev/module_param | success | Was 0 now: 0 |
| netdev/verify_signedoff | success | Signed-off-by tag matches author and committer |
| netdev/verify_fixes | success | No Fixes tag |
| netdev/build_allmodconfig_warn | success | Errors and warnings before: 0 this patch: 0 |
| netdev/checkpatch | success | total: 0 errors, 0 warnings, 0 checks, 57 lines checked |
| netdev/kdoc | success | Errors and warnings before: 0 this patch: 0 |
| netdev/source_inline | success | Was 0 now: 0 |
On Thu, Jan 27, 2022 at 12:12:39AM +0100, Tobias Waldekranz wrote: > Before this change, both the read and write callback would start out > by asserting that the chip's busy flag was cleared. However, both > callbacks also made sure to wait for the clearing of the busy bit > before returning - making the initial check superfluous. The only > time that would ever have an effect was if the busy bit was initially > set for some reason. > > With that in mind, make sure to perform an initial check of the busy > bit, after which both read and write can rely the previous operation > to have waited for the bit to clear. > > This cuts the number of operations on the underlying MDIO bus by 25% > > Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> Reviewed-by: Andrew Lunn <andrew@lunn.ch> Andrew
diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h index 8271b8aa7b71..438cee853d07 100644 --- a/drivers/net/dsa/mv88e6xxx/chip.h +++ b/drivers/net/dsa/mv88e6xxx/chip.h @@ -392,6 +392,7 @@ struct mv88e6xxx_chip { struct mv88e6xxx_bus_ops { int (*read)(struct mv88e6xxx_chip *chip, int addr, int reg, u16 *val); int (*write)(struct mv88e6xxx_chip *chip, int addr, int reg, u16 val); + int (*init)(struct mv88e6xxx_chip *chip); }; struct mv88e6xxx_mdio_bus { diff --git a/drivers/net/dsa/mv88e6xxx/smi.c b/drivers/net/dsa/mv88e6xxx/smi.c index a59f32243e08..1ebdaa55e710 100644 --- a/drivers/net/dsa/mv88e6xxx/smi.c +++ b/drivers/net/dsa/mv88e6xxx/smi.c @@ -104,11 +104,6 @@ static int mv88e6xxx_smi_indirect_read(struct mv88e6xxx_chip *chip, { int err; - err = mv88e6xxx_smi_direct_wait(chip, chip->sw_addr, - MV88E6XXX_SMI_CMD, 15, 0); - if (err) - return err; - err = mv88e6xxx_smi_direct_write(chip, chip->sw_addr, MV88E6XXX_SMI_CMD, MV88E6XXX_SMI_CMD_BUSY | @@ -132,11 +127,6 @@ static int mv88e6xxx_smi_indirect_write(struct mv88e6xxx_chip *chip, { int err; - err = mv88e6xxx_smi_direct_wait(chip, chip->sw_addr, - MV88E6XXX_SMI_CMD, 15, 0); - if (err) - return err; - err = mv88e6xxx_smi_direct_write(chip, chip->sw_addr, MV88E6XXX_SMI_DATA, data); if (err) @@ -155,9 +145,20 @@ static int mv88e6xxx_smi_indirect_write(struct mv88e6xxx_chip *chip, MV88E6XXX_SMI_CMD, 15, 0); } +static int mv88e6xxx_smi_indirect_init(struct mv88e6xxx_chip *chip) +{ + /* Ensure that the chip starts out in the ready state. As both + * reads and writes always ensure this on return, they can + * safely depend on the chip not being busy on entry. + */ + return mv88e6xxx_smi_direct_wait(chip, chip->sw_addr, + MV88E6XXX_SMI_CMD, 15, 0); +} + static const struct mv88e6xxx_bus_ops mv88e6xxx_smi_indirect_ops = { .read = mv88e6xxx_smi_indirect_read, .write = mv88e6xxx_smi_indirect_write, + .init = mv88e6xxx_smi_indirect_init, }; int mv88e6xxx_smi_init(struct mv88e6xxx_chip *chip, @@ -175,5 +176,8 @@ int mv88e6xxx_smi_init(struct mv88e6xxx_chip *chip, chip->bus = bus; chip->sw_addr = sw_addr; + if (chip->smi_ops->init) + return chip->smi_ops->init(chip); + return 0; }
Before this change, both the read and write callback would start out by asserting that the chip's busy flag was cleared. However, both callbacks also made sure to wait for the clearing of the busy bit before returning - making the initial check superfluous. The only time that would ever have an effect was if the busy bit was initially set for some reason. With that in mind, make sure to perform an initial check of the busy bit, after which both read and write can rely the previous operation to have waited for the bit to clear. This cuts the number of operations on the underlying MDIO bus by 25% Signed-off-by: Tobias Waldekranz <tobias@waldekranz.com> --- drivers/net/dsa/mv88e6xxx/chip.h | 1 + drivers/net/dsa/mv88e6xxx/smi.c | 24 ++++++++++++++---------- 2 files changed, 15 insertions(+), 10 deletions(-)