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

[Sean Anderson <seanga2@gmail.com>]

On 2/6/26 04:05, René Rebe wrote:
> 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:

I'm not really familiar enough with SPARC to say whether this is reasonable
or not. I've added the SPARC maintainers to CC so maybe they can comment.

> 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>
>