[net-next RFC PATCH v4 15/15] net: dsa: qca8k: cache lo and hi for mdio write

Ansuel Smith
2021-12-11T19:58:48Z

From Documentation, we can cache lo and hi the same way we do with the
page. This massively reduce the mdio write as 3/4 of the time we only
require to write the lo or hi part for a mdio write.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
---
drivers/net/dsa/qca8k.c | 49 ++++++++++++++++++++++++++++++++++++-----
1 file changed, 44 insertions(+), 5 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index 375a1d34e46f..b109a74031c6 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -94,6 +94,48 @@ qca8k_split_addr(u32 regaddr, u16 *r1, u16 *r2, u16 *page)
*page = regaddr & 0x3ff;
}

+static u16 qca8k_current_lo = 0xffff;
+
+static int
+qca8k_set_lo(struct mii_bus *bus, int phy_id, u32 regnum, u16 lo)
+{
+ int ret;
+
+ if (lo == qca8k_current_lo) {
+ // pr_info("SAME LOW");
+ return 0;
+ }
+
+ ret = bus->write(bus, phy_id, regnum, lo);
+ if (ret < 0)
+ dev_err_ratelimited(&bus->dev,
+ "failed to write qca8k 32bit lo register\n");
+
+ qca8k_current_lo = lo;
+ return 0;
+}
+
+static u16 qca8k_current_hi = 0xffff;
+
+static int
+qca8k_set_hi(struct mii_bus *bus, int phy_id, u32 regnum, u16 hi)
+{
+ int ret;
+
+ if (hi == qca8k_current_hi) {
+ // pr_info("SAME HI");
+ return 0;
+ }
+
+ ret = bus->write(bus, phy_id, regnum, hi);
+ if (ret < 0)
+ dev_err_ratelimited(&bus->dev,
+ "failed to write qca8k 32bit hi register\n");
+
+ qca8k_current_hi = hi;
+ return 0;
+}
+
static int
qca8k_mii_read32(struct mii_bus *bus, int phy_id, u32 regnum, u32 *val)
{
@@ -125,12 +167,9 @@ qca8k_mii_write32(struct mii_bus *bus, int phy_id, u32 regnum, u32 val)
lo = val & 0xffff;
hi = (u16)(val >> 16);

- ret = bus->write(bus, phy_id, regnum, lo);
+ ret = qca8k_set_lo(bus, phy_id, regnum, lo);
if (ret >= 0)
- ret = bus->write(bus, phy_id, regnum + 1, hi);
- if (ret < 0)
- dev_err_ratelimited(&bus->dev,
- "failed to write qca8k 32bit register\n");
+ ret = qca8k_set_hi(bus, phy_id, regnum + 1, hi);
}

static int
--
2.32.0