Re: [PATCH] net: sunhme: Fix sbus regression

["René Rebe" <rene@exactco.de>]

On Thu, 5 Feb 2026 20:41:11 -0500, Sean Anderson <seanga2@gmail.com> wrote:

> On 2/5/26 11:09, René Rebe wrote:
> > Commit cc216e4b44ce ("net: sunhme: Switch SBUS to devres") changed
> > explicit sized of_ioremap with BMAC_REG_SIZEs to
> > devm_platform_ioremap_resource mapping all the resource. However,
> > this does not work on my Sun Ultra 2 with SBUS HMEs:
> > hme f0072f38: error -EBUSY: can't request region for resource [mem
> > 0x1ffe8c07000-0x1ffe8c0701f]
> > hme f0072f38: Cannot map TCVR registers.
> > hme f0072f38: probe with driver hme failed with error -16
> > hme f007ab44: error -EBUSY: can't request region for resource [mem
> > 0x1ff28c07000-0x1ff28c0701f]
> > hme f007ab44: Cannot map TCVR registers.
> > hme f007ab44: probe with driver hme failed with error -16
> > Turns out the open-firmware resources overlap, at least on this
> > machines and PROM version:
> > hexdump /proc/device-tree/sbus@1f,0/SUNW,hme@2,8c00000/reg:
> > 00 00 00 02 08 c0 00 00  00 00 01 08
> > 00 00 00 02 08 c0 20 00  00 00 20 00
> > 00 00 00 02 08 c0 40 00  00 00 20 00
> > 00 00 00 02 08 c0 60 00  00 00 20 00
> > 00 00 00 02 08 c0 70 00  00 00 00 20
> > And the driver previously explicitly mapped way smaller mmio regions:
> > /proc/iomem:
> > 1ff28c00000-1ff28c00107 : HME Global Regs
> > 1ff28c02000-1ff28c02033 : HME TX Regs
> > 1ff28c04000-1ff28c0401f : HME RX Regs
> > 1ff28c06000-1ff28c0635f : HME BIGMAC Regs
> > 1ff28c07000-1ff28c0701f : HME Tranceiver Regs
> > Quirk this specific issue by truncating the previous resource to not
> > overlap into the TCVR registers.
> > Fixes: cc216e4b44ce ("net: sunhme: Switch SBUS to devres")
> > Signed-off-by: René Rebe <rene@exactco.de>
> > ---
> > Tested on Sun Ultra 2 running T2/Linux.
> > Alternatively we could explicitly size all regions, or check overlap
> > in startup code (I also already have a patch for that, too).
> 
> What does this look like?

This only checks for "sorted" overlaps w/ the previous res, but given
they probably usually are and it catches this case, ...

The downside is, it may break other devices, I only test booted this
on an Ultra 2 and Ultra 30. On the U2 it fixes the hme ethernet,
too. On the U30 it causes an eprom region to be truncated. I probably
should investiage that and test boot on all my SPARC systems before we
consider this. That's why I sent the trivial hme driver hotfix first.
Alternatively we could also overwrite all sbus res in the hme driver
with the previously used known good sizes. I can send a patch for
that, too if you like:

diff --git a/arch/sparc/kernel/of_device_64.c b/arch/sparc/kernel/of_device_64.c
index f53092b07b9e..8bd405cbc04f 100644
--- a/arch/sparc/kernel/of_device_64.c
+++ b/arch/sparc/kernel/of_device_64.c
@@ -412,6 +412,15 @@ static void __init build_device_resources(struct platform_device *op,
 			r->start = result;
 			r->end = result + size - 1;
 			r->flags = flags;
+
+			/* check for and correct simple bogusly overlapping resources */
+			if (index > 0 &&
+			    op->resource[index-1].start <= r->end &&
+			    op->resource[index-1].end > r->start) {
+				printk(KERN_WARNING "%pOF: prev regs overlap (%x), limiting %x.\n",
+				       op->dev.of_node, op->resource[index-1].end, r->start - 1);
+				op->resource[index-1].end = r->start - 1;
+			}
 		}
 		r->name = op->dev.of_node->full_name;
 	}


> > ---
> > --- linux-6.18/drivers/net/ethernet/sun/sunhme.c.vanilla 2026-02-05
> > --- 11:50:33.288906134 +0100
> > +++ linux-6.18/drivers/net/ethernet/sun/sunhme.c 2026-02-05
> > 11:55:22.541384377 +0100
> > @@ -2551,6 +2551,9 @@
> >   		goto err_out_clear_quattro;
> >   	}
> >   +	/* BIGMAC may have bogus sizes */
> > + if ((op->resource[3].end - op->resource[3].start) >= BMAC_REG_SIZE)
> > + op->resource[3].end = op->resource[3].start + BMAC_REG_SIZE - 1;
> >   	hp->bigmacregs = devm_platform_ioremap_resource(op, 3);
> >   	if (IS_ERR(hp->bigmacregs)) {
> >   		dev_err(&op->dev, "Cannot map BIGMAC registers.\n");
> > 
> 
> Reviewed-by: Sean Anderson <seanga2@gmail.com>

-- 
René Rebe, ExactCODE GmbH, Berlin, Germany
https://exactco.de • https://t2linux.com • https://patreon.com/renerebe