On Sun, 19 Mar 2023 at 10:45, Álvaro Fernández Rojas <noltari@xxxxxxxxx> wrote: > > El vie, 17 mar 2023 a las 17:41, Florian Fainelli > (<f.fainelli@xxxxxxxxx>) escribió: > > > > On 3/17/23 09:23, Álvaro Fernández Rojas wrote: > > > El vie, 17 mar 2023 a las 15:29, Vladimir Oltean (<olteanv@xxxxxxxxx>) escribió: > > >> > > >> On Fri, Mar 17, 2023 at 03:17:12PM +0100, Álvaro Fernández Rojas wrote: > > >>>> The proposed solution is too radical for a problem that was not properly > > >>>> characterized yet, so this patch set has my temporary NACK. > > >>> > > >>> Forgive me, but why do you consider this solution too radical? > > >> > > >> Because it involves changing device tree bindings (stable ABI) in an > > >> incompatible way. > > >> > > >>>> > > >>>>> But maybe Florian or Jonas can give some more details about the issue... > > >>>> > > >>>> I think you also have the tools necessary to investigate this further. > > >>>> We need to know what resource belonging to the switch is it that the > > >>>> MDIO mux needs. Where is the earliest place you can add the call to > > >>>> b53_mmap_mdiomux_init() such that your board works reliably? Note that > > >>>> b53_switch_register() indirectly calls b53_setup(). By placing this > > >>>> function where you have, the entirety of b53_setup() has finished > > >>>> execution, and we don't know exactly what is it from there that is > > >>>> needed. > > >>> > > >>> In the following link you will find different bootlogs related to > > >>> different scenarios all of them with the same result: any attempt of > > >>> calling b53_mmap_mdiomux_init() earlier than b53_switch_register() > > >>> will either result in a kernel panic or a device hang: > > >>> https://gist.github.com/Noltari/b0bd6d5211160ac7bf349d998d21e7f7 > > >>> > > >>> 1. before b53_switch_register(): > > >>> > > >>> 2. before dsa_register_switch(): > > >>> > > >>> 3. before b53_switch_init(): > > >> > > >> Did you read what I said? > > > > > > Yes, but I didn't get your point, sorry for that. > > > > > >> > > >> | Note that b53_switch_register() indirectly calls b53_setup(). By placing > > >> | this function where you have, the entirety of b53_setup() has finished > > >> | execution, and we don't know exactly what is it from there that is > > >> | needed. > > >> > > >> Can you place the b53_mmap_mdiomux_init() in various places within > > >> b53_setup() to restrict the search further? > > > > > > I tried and these are the results: > > > https://gist.github.com/Noltari/d5bdba66b8f2e392c9e4c2759661d862 > > > > > > All of them hang when dsa_tree_setup() is called for DSA tree 1 > > > (external switch) without having completely setup DSA tree 0 (internal > > > switch): > > > [ 1.471345] b53-switch 10e00000.switch: found switch: BCM63xx, rev 0 > > > [ 1.481099] bcm6368-enetsw 1000d800.ethernet: IRQ tx not found > > > [ 1.506752] bcm6368-enetsw 1000d800.ethernet: mtd mac 4c:60:de:86:52:12 > > > [ 1.594365] bcm7038-wdt 1000005c.watchdog: Registered BCM7038 Watchdog > > > [ 1.612008] NET: Registered PF_INET6 protocol family > > > [ 1.645617] Segment Routing with IPv6 > > > [ 1.649547] In-situ OAM (IOAM) with IPv6 > > > [ 1.653948] NET: Registered PF_PACKET protocol family > > > [ 1.659984] 8021q: 802.1Q VLAN Support v1.8 > > > [ 1.699193] b53-switch 10e00000.switch: found switch: BCM63xx, rev 0 > > > [ 2.124257] bcm53xx 0.1:1e: found switch: BCM53125, rev 4 > > > *** Device hang *** > > > > > > I don't know if there's a way to defer the probe of DSA tree 1 (the > > > external switch) until DSA tree 0 (the internal switch) is completely > > > setup, because that would probably be the only alternative way of > > > fixing this. > > > > Could you find out which part is hanging? It looks like there is a busy > > waiting operation that we never complete? > > After many tests I was able to find the part that was hanging the device. > It turns out that if the MDIO bus controller is registered soon > enough, b53_phy_read16 will be called for the RGMII port on the > internal switch: > [ 4.042698] b53-switch 10e00000.switch: b53_phy_read16: ds=81fede80 > phy_read16=00000000 addr=4 reg=2 > It turns out that the device is hanging on the following line of > b53_phy_read16(): > b53_read16(priv, B53_PORT_MII_PAGE(addr), reg * 2, &value); > Maybe it's not safe to access B53_PORT_MII_PAGE() on MMAP switches? If you are following the example from 1/3, then I think I see what the issue might be here: You are labeling the port where the external switch is connected as "extsw", which is neither "cpu" nor "dsa", so it is treated as a normal/user port (which it shouldn't). If you change its label to "dsa" (which AFAIU would be the correct one to denote a daisy chained switch) it should not try to access port 4's MDIO registers (via the slave mdio bus). Can you check if that helps? Regards Jonas
