diff mbox series

[v2,net] net: dsa: mv88e6xxx: Avoid EEPROM timeout when EEPROM is absent

Message ID 20230920184647.84316-1-festevam@gmail.com (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series [v2,net] net: dsa: mv88e6xxx: Avoid EEPROM timeout when EEPROM is absent | expand

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netdev/series_format success Single patches do not need cover letters
netdev/tree_selection success Clearly marked for net
netdev/fixes_present success Fixes tag present in non-next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 1340 this patch: 1340
netdev/cc_maintainers success CCed 9 of 9 maintainers
netdev/build_clang success Errors and warnings before: 1363 this patch: 1363
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 1363 this patch: 1363
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 34 lines checked
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0

Commit Message

Fabio Estevam Sept. 20, 2023, 6:46 p.m. UTC 
From: Fabio Estevam <festevam@denx.de>

Since commit 23d775f12dcd ("net: dsa: mv88e6xxx: Wait for EEPROM done
before HW reset") the following error is seen on a imx8mn board with
a 88E6320 switch:

mv88e6085 30be0000.ethernet-1:00: Timeout waiting for EEPROM done

This board does not have an EEPROM attached to the switch though.

This problem is well explained by Andrew Lunn:

"If there is an EEPROM, and the EEPROM contains a lot of data, it could
be that when we perform a hardware reset towards the end of probe, it
interrupts an I2C bus transaction, leaving the I2C bus in a bad state,
and future reads of the EEPROM do not work.

The work around for this was to poll the EEInt status and wait for it
to go true before performing the hardware reset.

However, we have discovered that for some boards which do not have an
EEPROM, EEInt never indicates complete. As a result,
mv88e6xxx_g1_wait_eeprom_done() spins for a second and then prints a
warning.

We probably need a different solution than calling
mv88e6xxx_g1_wait_eeprom_done(). The datasheet for 6352 documents the
EEPROM Command register:

bit 15 is:

  EEPROM Unit Busy. This bit must be set to a one to start an EEPROM
  operation (see EEOp below). Only one EEPROM operation can be
  executing at one time so this bit must be zero before setting it to
  a one.  When the requested EEPROM operation completes this bit will
  automatically be cleared to a zero. The transition of this bit from
  a one to a zero can be used to generate an interrupt (the EEInt in
  Global 1, offset 0x00).

and more interesting is bit 11:

  Register Loader Running. This bit is set to one whenever the
  register loader is busy executing instructions contained in the
  EEPROM."

Change to mv88e6xxx_g2_eeprom_wait() to fix the timeout error when the
EEPROM chip is not present.
  
Fixes: 23d775f12dcd ("net: dsa: mv88e6xxx: Wait for EEPROM done before HW reset")
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
Alfred,

Please test it, if you have a chance. I want to be sure that your usecase
still works well.

Changes since v1:
- Use the correct function name in the last sentence: 
"Change to mv88e6xxx_g2_eeprom_wait() to fix the timeout ..."
- Collected Florian's tag.
- Passed the net prefix in the Subject line.

 drivers/net/dsa/mv88e6xxx/chip.c    | 6 ++++--
 drivers/net/dsa/mv88e6xxx/global2.c | 2 +-
 drivers/net/dsa/mv88e6xxx/global2.h | 2 ++
 3 files changed, 7 insertions(+), 3 deletions(-)

Comments

Fabio Estevam Sept. 21, 2023, 12:58 p.m. UTC | #1 
On Wed, Sep 20, 2023 at 3:47 PM Fabio Estevam <festevam@gmail.com> wrote:

> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -3012,14 +3012,16 @@ static void mv88e6xxx_hardware_reset(struct mv88e6xxx_chip *chip)
>                  * from the wrong location resulting in the switch booting
>                  * to wrong mode and inoperable.
>                  */
> -               mv88e6xxx_g1_wait_eeprom_done(chip);
> +               if (chip->info->ops->get_eeprom)
> +                       mv88e6xxx_g2_eeprom_wait(chip);

Just realized that I should also remove the
mv88e6xxx_g1_wait_eeprom_done() definition, as it becomes unused now.

I will send a v3 with such a change, but will wait for more comments first.
diff mbox series

Patch

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index a73008b9e0b3..ba906dfab055 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -3012,14 +3012,16 @@  static void mv88e6xxx_hardware_reset(struct mv88e6xxx_chip *chip)
 		 * from the wrong location resulting in the switch booting
 		 * to wrong mode and inoperable.
 		 */
-		mv88e6xxx_g1_wait_eeprom_done(chip);
+		if (chip->info->ops->get_eeprom)
+			mv88e6xxx_g2_eeprom_wait(chip);
 
 		gpiod_set_value_cansleep(gpiod, 1);
 		usleep_range(10000, 20000);
 		gpiod_set_value_cansleep(gpiod, 0);
 		usleep_range(10000, 20000);
 
-		mv88e6xxx_g1_wait_eeprom_done(chip);
+		if (chip->info->ops->get_eeprom)
+			mv88e6xxx_g2_eeprom_wait(chip);
 	}
 }
 
diff --git a/drivers/net/dsa/mv88e6xxx/global2.c b/drivers/net/dsa/mv88e6xxx/global2.c
index ec49939968fa..ac302a935ce6 100644
--- a/drivers/net/dsa/mv88e6xxx/global2.c
+++ b/drivers/net/dsa/mv88e6xxx/global2.c
@@ -340,7 +340,7 @@  int mv88e6xxx_g2_pot_clear(struct mv88e6xxx_chip *chip)
  * Offset 0x15: EEPROM Addr (for 8-bit data access)
  */
 
-static int mv88e6xxx_g2_eeprom_wait(struct mv88e6xxx_chip *chip)
+int mv88e6xxx_g2_eeprom_wait(struct mv88e6xxx_chip *chip)
 {
 	int bit = __bf_shf(MV88E6XXX_G2_EEPROM_CMD_BUSY);
 	int err;
diff --git a/drivers/net/dsa/mv88e6xxx/global2.h b/drivers/net/dsa/mv88e6xxx/global2.h
index c05fad5c9f19..6d8d38944b23 100644
--- a/drivers/net/dsa/mv88e6xxx/global2.h
+++ b/drivers/net/dsa/mv88e6xxx/global2.h
@@ -360,6 +360,8 @@  int mv88e6xxx_g2_trunk_clear(struct mv88e6xxx_chip *chip);
 int mv88e6xxx_g2_device_mapping_write(struct mv88e6xxx_chip *chip, int target,
 				      int port);
 
+int mv88e6xxx_g2_eeprom_wait(struct mv88e6xxx_chip *chip);
+
 extern const struct mv88e6xxx_irq_ops mv88e6097_watchdog_ops;
 extern const struct mv88e6xxx_irq_ops mv88e6250_watchdog_ops;
 extern const struct mv88e6xxx_irq_ops mv88e6390_watchdog_ops;