Messages in this thread | | | Date | Tue, 30 May 2023 19:28:19 +0200 | From | Andrew Lunn <> | Subject | Re: [PATCH net] net: dsa: mv88e6xxx: Increase wait after reset deactivation |
| |
On Tue, May 30, 2023 at 04:52:23PM +0200, Andreas Svensson wrote: > A switch held in reset by default needs to wait longer until we can > reliably detect it. > > An issue was observed when testing on the Marvell 88E6393X (Link Street). > The driver failed to detect the switch on some upstarts. Increasing the > wait time after reset deactivation solves this issue. > > The updated wait time is now also the same as the wait time in the > mv88e6xxx_hardware_reset function.
Do you have an EEPROM attached and content in it?
It is not necessarily the reset itself which is the problem, but how long it takes after the reset to read the contents of the EEPROM. While it is doing that, is does not respond on the MDIO bus. Which is why mv88e6xxx_hardware_reset() polls for that to complete.
I know there are some users who want the switch to boot as fast as possible, and don't really want the additional 9ms delay. But this is also a legitimate change. I'm just wondering if we need to consider a DT property here for those with EEPROM content. Or, if there is an interrupt line, wait for the EEPROM complete interrupt. We just have tricky chicken and egg problems. At this point in time, we don't actually know if the devices exists or not.
Andrew
| |