Messages in this thread | | | Date | Fri, 13 Jan 2023 14:20:17 +0100 | From | Lukasz Majewski <> | Subject | Re: [PATCH v4 1/3] dsa: marvell: Provide per device information about max frame size |
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Hi Vladimir,
> On Fri, Jan 13, 2023 at 01:13:31PM +0100, Lukasz Majewski wrote: > > I think that this commit [1], made the adjustment to fix yet another > > issue. > > [1] - > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b9c587fed61cf88bd45822c3159644445f6d5aa6 > > > > It appears that this is the commit to blame, indeed. > > > It looks like the missing 8 bytes are added in the > > mv88e6xxx_change_mtu() function. > > Only for DSA and CPU ports. The driver still behaves as if the max MTU > on user ports is 1492 bytes. >
It looks so...
> > > I wonder, shouldn't we first fix that, and apply this patch set > > > afterwards? > > > > IMHO, it is up to Andrew to decide how to proceed, as the > > aforementioned patch [1] is an attempt to fix yet another issue [2]. > > [2] - > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1baf0fac10fbe3084975d7cb0a4378eb18871482 > > > > I think the handling for those switches were neither > port_set_jumbo_size() nor set_max_frame_size() is present is just a > roundabout way of saying "hey, I only support ETH_DATA_LEN MTU and > can't change it, leave me alone". But it isn't what the code does.
I tend to agree... The number of switched which suppor 1522 B max frame is only six. This may be why the problem was not noticed.
The fixed function maybe should look like below:
static int mv88e6xxx_get_max_mtu(struct dsa_switch *ds, int port) { ....
int max_mtu;
max_mtu = chip->info->max_frame_size - VLAN_ETH_HLEN - ETH_FCS_LE;
if (dsa_is_dsa_port(ds, port) || dsa_is_cpu_port(ds, port)) max_mtu -= EDSA_HLEN;
return max_mtu; }
Comments more than welcome.
Best regards,
Lukasz Majewski
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