Messages in this thread | | | Date | Wed, 27 Sep 2023 14:12:39 +0200 | From | Andrew Lunn <> | Subject | Re: [PATCH v3 net] net: dsa: mv88e6xxx: Avoid EEPROM timeout when EEPROM is absent |
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On Fri, Sep 22, 2023 at 09:47:41AM -0300, Fabio Estevam wrote: > 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 using 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>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Andrew
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