[RFC PATCH v7 14/16] net: dsa: qca8k: cache lo and hi for mdio write

Ansuel Smith
2022-01-23T01:34:16Z

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 as 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 | 60 ++++++++++++++++++++++++++++++++---------
drivers/net/dsa/qca8k.h | 5 ++++
2 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/drivers/net/dsa/qca8k.c b/drivers/net/dsa/qca8k.c
index c2f5414033d8..2a43fb9aeef2 100644
--- a/drivers/net/dsa/qca8k.c
+++ b/drivers/net/dsa/qca8k.c
@@ -88,6 +88,42 @@ qca8k_split_addr(u32 regaddr, u16 *r1, u16 *r2, u16 *page)
*page = regaddr & 0x3ff;
}

+static int
+qca8k_set_lo(struct mii_bus *bus, int phy_id, u32 regnum,
+ u16 lo, u16 *cached_lo)
+{
+ int ret;
+
+ if (lo == *cached_lo)
+ 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");
+
+ *cached_lo = lo;
+ return 0;
+}
+
+static int
+qca8k_set_hi(struct mii_bus *bus, int phy_id, u32 regnum,
+ u16 hi, u16 *cached_hi)
+{
+ int ret;
+
+ if (hi == *cached_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");
+
+ *cached_hi = hi;
+ return 0;
+}
+
static int
qca8k_mii_read32(struct mii_bus *bus, int phy_id, u32 regnum, u32 *val)
{
@@ -111,7 +147,8 @@ qca8k_mii_read32(struct mii_bus *bus, int phy_id, u32 regnum, u32 *val)
}

static void
-qca8k_mii_write32(struct mii_bus *bus, int phy_id, u32 regnum, u32 val)
+qca8k_mii_write32(struct mii_bus *bus, struct qca8k_mdio_cache *cache,
+ int phy_id, u32 regnum, u32 val)
{
u16 lo, hi;
int ret;
@@ -119,12 +156,9 @@ 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, &cache->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, &cache->hi);
}

static int
@@ -384,7 +418,7 @@ qca8k_regmap_write(void *ctx, uint32_t reg, uint32_t val)
if (ret < 0)
goto exit;

- qca8k_mii_write32(bus, 0x10 | r2, r1, val);
+ qca8k_mii_write32(bus, mdio_cache, 0x10 | r2, r1, val);

exit:
mutex_unlock(&bus->mdio_lock);
@@ -421,7 +455,7 @@ qca8k_regmap_update_bits(void *ctx, uint32_t reg, uint32_t mask, uint32_t write_

val &= ~mask;
val |= write_val;
- qca8k_mii_write32(bus, 0x10 | r2, r1, val);
+ qca8k_mii_write32(bus, mdio_cache, 0x10 | r2, r1, val);

exit:
mutex_unlock(&bus->mdio_lock);
@@ -1072,14 +1106,14 @@ qca8k_mdio_write(struct mii_bus *bus, struct qca8k_mdio_cache *cache,
if (ret)
goto exit;

- qca8k_mii_write32(bus, 0x10 | r2, r1, val);
+ qca8k_mii_write32(bus, cache, 0x10 | r2, r1, val);

ret = qca8k_mdio_busy_wait(bus, QCA8K_MDIO_MASTER_CTRL,
QCA8K_MDIO_MASTER_BUSY);

exit:
/* even if the busy_wait timeouts try to clear the MASTER_EN */
- qca8k_mii_write32(bus, 0x10 | r2, r1, 0);
+ qca8k_mii_write32(bus, cache, 0x10 | r2, r1, 0);

mutex_unlock(&bus->mdio_lock);

@@ -1109,7 +1143,7 @@ qca8k_mdio_read(struct mii_bus *bus, struct qca8k_mdio_cache *cache,
if (ret)
goto exit;

- qca8k_mii_write32(bus, 0x10 | r2, r1, val);
+ qca8k_mii_write32(bus, cache, 0x10 | r2, r1, val);

ret = qca8k_mdio_busy_wait(bus, QCA8K_MDIO_MASTER_CTRL,
QCA8K_MDIO_MASTER_BUSY);
@@ -1120,7 +1154,7 @@ qca8k_mdio_read(struct mii_bus *bus, struct qca8k_mdio_cache *cache,

exit:
/* even if the busy_wait timeouts try to clear the MASTER_EN */
- qca8k_mii_write32(bus, 0x10 | r2, r1, 0);
+ qca8k_mii_write32(bus, cache, 0x10 | r2, r1, 0);

mutex_unlock(&bus->mdio_lock);

@@ -3007,6 +3041,8 @@ qca8k_sw_probe(struct mdio_device *mdiodev)
}

priv->mdio_cache.page = 0xffff;
+ priv->mdio_cache.lo = 0xffff;
+ priv->mdio_cache.hi = 0xffff;

/* Check the detected switch id */
ret = qca8k_read_switch_id(priv);
diff --git a/drivers/net/dsa/qca8k.h b/drivers/net/dsa/qca8k.h
index 77ffdc7b5aaa..9ecd4d221906 100644
--- a/drivers/net/dsa/qca8k.h
+++ b/drivers/net/dsa/qca8k.h
@@ -369,6 +369,11 @@ struct qca8k_mdio_cache {
* mdio writes
*/
u16 page;
+/* lo and hi can also be cached and from Documentation we can skip one
+ * extra mdio write if lo or hi is didn't change.
+ */
+ u16 lo;
+ u16 hi;
};

struct qca8k_priv {
--
2.33.1