On Sun, 2013-11-17 at 10:43 +0000, Ian Campbell wrote: > On Sun, 2013-11-17 at 10:12 +0100, Michael Stapelberg wrote: > > Hi Lennert, > > > > Lennert Buytenhek <buyt...@wantstofly.org> writes: > > > The problem here was that the Marvell PHY driver at some point supported > > > one or two specific Marvell ethernet PHY models, and people then started > > > blindly adding new PHY IDs to it without checking whether the already > > > supported PHYs and the PHYs for which support was being added had common > > > register layouts (and they didn't). > > > > > > The result is that on some of the very common Marvell PHYs that this > > > driver claims to support, the driver does sequences of register writes > > > that have entirely different effects than the intended ones, causing > > > various unintended side effects, including complete link failure, and > > > e.g. on the quad ethernet PHY on some of the mv78xx0 development > > > boards, having the Marvell PHY driver enabled causes link to flap on > > > the other three ports if you plug/unplug one of the ports because the > > > driver thinks it's a good idea to hard reset the whole chip under > > > these circumstances... > > > > > > What needs to be done is that someone with access to the relevant > > > Marvell datasheets fix the driver to behave according to which chip > > > it's being used on. It's quite a bit of work to sort out this mess, > > > easily several tens of hours -- I started looking into it when I was > > > still at Marvell, but didn't get it done before leaving. > > Thanks for clarifying. This sounds like it would not be a wise choice to > > enable this option again :-(. > > I'm in two minds about this. > > The issues have been described in general terms but we don't have any > specifics for the platforms supported by Debian. Are any of those known > specifically to be broken?
Yes, the DB-78xx0-BP development boards. The number of ports is the last-but-one digit in the PHY model number so we could remove everything with a 4 there. > Realistically I expect the only way this is going to get fixed in > practice is if we enable this option and deal with any resulting bug > reports either by fixing/disabling that phy driver or by forwarding > upstream. > > A bunch of the phy ids seem to be duplicated in several phy drivers. [...] > Should we be disabling some seleciton of these, or do PHYID's not mean > what I think? Most network drivers do not use phylib and the fact that they recognise and configure the same Marvell PHYs directly does not mean anything. Ben. -- Ben Hutchings Beware of bugs in the above code; I have only proved it correct, not tried it. - Donald Knuth
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