[RFC PATCH 1/1] mv88e6xxx: Cache scratch config of 6352 in setup
From: Fidan Aliyeva
Date: Sun May 10 2026 - 17:35:14 EST
In mv88e6352 scratch register in Global Control 2 set of registers
returns which port is attached to SERDES. This value is set and
stays constant after the switch is released from reset; thus, it
can be cached during chip setup instead of reading the register
everytime when SERDES config is needed.
1. Add setup_chip_specific member to mv88e6xxx_ops and
g2_scratch_config3 member to mv88e6xxx_chip.
2. Add mv88e6352_g2_cache_global_scratch_config3 function as
.setup_chip_specific which reads the CONFIG3 value from the scratch
register and caches it.
3. Call .setup_chip_specific during chip setup.
4. Refactor mv88e6352_g2_scratch_port_has_serdes to use the cached
value.
5. Remove the locks surrounding mv88e6352_g2_scratch_port_has_serdes.
Not needed anymore since no register access in the function.
Co-developed-by: Thomas Eckerman <thomas.eckerman.ext@xxxxxxxxxxxx>
Signed-off-by: Thomas Eckerman <thomas.eckerman.ext@xxxxxxxxxxxx>
Signed-off-by: Fidan Aliyeva <fidan.aliyeva.ext@xxxxxxxxxxxx>
---
drivers/net/dsa/mv88e6xxx/chip.c | 13 ++++++--
drivers/net/dsa/mv88e6xxx/chip.h | 6 ++++
drivers/net/dsa/mv88e6xxx/global2.h | 1 +
drivers/net/dsa/mv88e6xxx/global2_scratch.c | 36 +++++++++++++++------
drivers/net/dsa/mv88e6xxx/pcs-6352.c | 2 --
drivers/net/dsa/mv88e6xxx/serdes.c | 2 --
6 files changed, 44 insertions(+), 16 deletions(-)
diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 8ca5fd40df92..ab354bc2e2f1 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -685,9 +685,6 @@ static void mv88e6352_phylink_get_caps(struct mv88e6xxx_chip *chip, int port,
/* Port 4 supports automedia if the serdes is associated with it. */
if (port == 4) {
err = mv88e6352_g2_scratch_port_has_serdes(chip, port);
- if (err < 0)
- dev_err(chip->dev, "p%d: failed to read scratch\n",
- port);
if (err <= 0)
return;
@@ -3997,6 +3994,12 @@ static int mv88e6xxx_setup(struct dsa_switch *ds)
goto unlock;
}
+ if (chip->info->ops->setup_chip_specific) {
+ err = chip->info->ops->setup_chip_specific(chip);
+ if (err)
+ goto unlock;
+ }
+
/* Cache the cmode of each port. */
for (i = 0; i < mv88e6xxx_num_ports(chip); i++) {
if (chip->info->ops->port_get_cmode) {
@@ -4662,6 +4665,7 @@ static const struct mv88e6xxx_ops mv88e6172_ops = {
.vtu_loadpurge = mv88e6352_g1_vtu_loadpurge,
.stu_getnext = mv88e6352_g1_stu_getnext,
.stu_loadpurge = mv88e6352_g1_stu_loadpurge,
+ .setup_chip_specific = mv88e6352_g2_cache_global_scratch_config3,
.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
.serdes_get_regs = mv88e6352_serdes_get_regs,
.gpio_ops = &mv88e6352_gpio_ops,
@@ -4765,6 +4769,7 @@ static const struct mv88e6xxx_ops mv88e6176_ops = {
.vtu_loadpurge = mv88e6352_g1_vtu_loadpurge,
.stu_getnext = mv88e6352_g1_stu_getnext,
.stu_loadpurge = mv88e6352_g1_stu_loadpurge,
+ .setup_chip_specific = mv88e6352_g2_cache_global_scratch_config3,
.serdes_irq_mapping = mv88e6352_serdes_irq_mapping,
.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
.serdes_get_regs = mv88e6352_serdes_get_regs,
@@ -5040,6 +5045,7 @@ static const struct mv88e6xxx_ops mv88e6240_ops = {
.vtu_loadpurge = mv88e6352_g1_vtu_loadpurge,
.stu_getnext = mv88e6352_g1_stu_getnext,
.stu_loadpurge = mv88e6352_g1_stu_loadpurge,
+ .setup_chip_specific = mv88e6352_g2_cache_global_scratch_config3,
.serdes_irq_mapping = mv88e6352_serdes_irq_mapping,
.serdes_get_regs_len = mv88e6352_serdes_get_regs_len,
.serdes_get_regs = mv88e6352_serdes_get_regs,
@@ -5475,6 +5481,7 @@ static const struct mv88e6xxx_ops mv88e6352_ops = {
.gpio_ops = &mv88e6352_gpio_ops,
.avb_ops = &mv88e6352_avb_ops,
.ptp_ops = &mv88e6352_ptp_ops,
+ .setup_chip_specific = mv88e6352_g2_cache_global_scratch_config3,
.serdes_get_sset_count = mv88e6352_serdes_get_sset_count,
.serdes_get_strings = mv88e6352_serdes_get_strings,
.serdes_get_stats = mv88e6352_serdes_get_stats,
diff --git a/drivers/net/dsa/mv88e6xxx/chip.h b/drivers/net/dsa/mv88e6xxx/chip.h
index 2b235ac2c5df..683f5a626f34 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.h
+++ b/drivers/net/dsa/mv88e6xxx/chip.h
@@ -454,6 +454,9 @@ struct mv88e6xxx_chip {
/* TCAM entries */
struct mv88e6xxx_tcam tcam;
+
+ /* Global2 scratch register config data3 */
+ u8 g2_scratch_config3;
};
#define TCAM_MATCH_SIZE 96
@@ -719,6 +722,9 @@ struct mv88e6xxx_ops {
/* Ternary Content Addressable Memory operations */
const struct mv88e6xxx_tcam_ops *tcam_ops;
+
+ /* Apply chip specific setup steps */
+ int (*setup_chip_specific)(struct mv88e6xxx_chip *chip);
};
struct mv88e6xxx_irq_ops {
diff --git a/drivers/net/dsa/mv88e6xxx/global2.h b/drivers/net/dsa/mv88e6xxx/global2.h
index 82f9b410de0b..ff5adf7c9bc3 100644
--- a/drivers/net/dsa/mv88e6xxx/global2.h
+++ b/drivers/net/dsa/mv88e6xxx/global2.h
@@ -382,6 +382,7 @@ int mv88e6390_g2_scratch_gpio_set_smi(struct mv88e6xxx_chip *chip,
bool external);
int mv88e6393x_g2_scratch_gpio_set_smi(struct mv88e6xxx_chip *chip,
bool external);
+int mv88e6352_g2_cache_global_scratch_config3(struct mv88e6xxx_chip *chip);
int mv88e6352_g2_scratch_port_has_serdes(struct mv88e6xxx_chip *chip, int port);
int mv88e6xxx_g2_atu_stats_set(struct mv88e6xxx_chip *chip, u16 kind, u16 bin);
int mv88e6xxx_g2_atu_stats_get(struct mv88e6xxx_chip *chip, u16 *stats);
diff --git a/drivers/net/dsa/mv88e6xxx/global2_scratch.c b/drivers/net/dsa/mv88e6xxx/global2_scratch.c
index 53a6d3ed63b3..e57b25aa2a4c 100644
--- a/drivers/net/dsa/mv88e6xxx/global2_scratch.c
+++ b/drivers/net/dsa/mv88e6xxx/global2_scratch.c
@@ -322,18 +322,18 @@ int mv88e6393x_g2_scratch_gpio_set_smi(struct mv88e6xxx_chip *chip,
}
/**
- * mv88e6352_g2_scratch_port_has_serdes - indicate if a port can have a serdes
+ * mv88e6352_g2_cache_global_scratch_config3 - caches G2 CONFIG3 value
* @chip: chip private data
- * @port: port number to check for serdes
*
- * Indicates whether the port may have a serdes attached according to the
- * pin strapping. Returns negative error number, 0 if the port is not
- * configured to have a serdes, and 1 if the port is configured to have a
- * serdes attached.
+ * Reads and stores config3 value of global2 scratch registers, which
+ * can be used to determine if the port is attached to a serdes. The
+ * value does not change once the switch is released from reset. Returns
+ * negative error number if the register read fails; otherwise, 0
*/
-int mv88e6352_g2_scratch_port_has_serdes(struct mv88e6xxx_chip *chip, int port)
+
+int mv88e6352_g2_cache_global_scratch_config3(struct mv88e6xxx_chip *chip)
{
- u8 config3, p;
+ u8 config3;
int err;
err = mv88e6xxx_g2_scratch_read(chip, MV88E6352_G2_SCRATCH_CONFIG_DATA3,
@@ -341,7 +341,25 @@ int mv88e6352_g2_scratch_port_has_serdes(struct mv88e6xxx_chip *chip, int port)
if (err)
return err;
- if (config3 & MV88E6352_G2_SCRATCH_CONFIG_DATA3_S_SEL)
+ chip->g2_scratch_config3 = config3;
+
+ return 0;
+}
+
+/**
+ * mv88e6352_g2_scratch_port_has_serdes - indicate if a port has serdes
+ * @chip: chip private data
+ * @port: port number to check for serdes
+ *
+ * Indicates whether the port may have a serdes attached according to the
+ * pin strapping. Returns 0 if the port is not configured to have a serdes, and
+ * 1 if the port is configured to have a serdes attached.
+ */
+int mv88e6352_g2_scratch_port_has_serdes(struct mv88e6xxx_chip *chip, int port)
+{
+ u8 p;
+
+ if (chip->g2_scratch_config3 & MV88E6352_G2_SCRATCH_CONFIG_DATA3_S_SEL)
p = 5;
else
p = 4;
diff --git a/drivers/net/dsa/mv88e6xxx/pcs-6352.c b/drivers/net/dsa/mv88e6xxx/pcs-6352.c
index 9ebf0f89f817..308655d72d52 100644
--- a/drivers/net/dsa/mv88e6xxx/pcs-6352.c
+++ b/drivers/net/dsa/mv88e6xxx/pcs-6352.c
@@ -326,9 +326,7 @@ static int mv88e6352_pcs_init(struct mv88e6xxx_chip *chip, int port)
unsigned int irq;
int err;
- mv88e6xxx_reg_lock(chip);
err = mv88e6352_g2_scratch_port_has_serdes(chip, port);
- mv88e6xxx_reg_unlock(chip);
if (err <= 0)
return err;
diff --git a/drivers/net/dsa/mv88e6xxx/serdes.c b/drivers/net/dsa/mv88e6xxx/serdes.c
index a936ee80ce00..d3d3c121a32d 100644
--- a/drivers/net/dsa/mv88e6xxx/serdes.c
+++ b/drivers/net/dsa/mv88e6xxx/serdes.c
@@ -202,9 +202,7 @@ int mv88e6352_serdes_get_regs_len(struct mv88e6xxx_chip *chip, int port)
{
int err;
- mv88e6xxx_reg_lock(chip);
err = mv88e6352_g2_scratch_port_has_serdes(chip, port);
- mv88e6xxx_reg_unlock(chip);
if (err <= 0)
return err;
--
2.36.0