linux-kernel - Re: [PATCH] of/fdt: fix error checking for earlycon address

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Date:	Wed, 28 Oct 2015 10:56:22 -0400
From:	Peter Hurley <peter@...leysoftware.com>
To:	Rob Herring <robh@...nel.org>
Cc:	Masahiro Yamada <yamada.masahiro@...ionext.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	Frank Rowand <frowand.list@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Ley Foon Tan <lftan@...era.com>
Subject: Re: [PATCH] of/fdt: fix error checking for earlycon address

On 10/27/2015 04:46 PM, Rob Herring wrote:
> On Fri, Oct 23, 2015 at 8:15 AM, Peter Hurley <peter@...leysoftware.com> wrote:
>> Hi Masahiro,
>>
>> On 10/23/2015 07:47 AM, Masahiro Yamada wrote:
>>> fdt_translate_address() returns OF_BAD_ADDR on error.  It is defined as
>>> a u64 value, so the variable "addr" should be defined as u64 as well.
>>
>> Good catch.
>>
>> I would prefer if fdt_translate_address() returned resource_size_t (which
>> is the proper type for handling addresses as integers) and that type
>> was propagated through early_init_dt_scan_chosen_serial => of_setup_earlycon.
> 
> That can be problematic in the DT code. The size of resource_size_t
> can vary on 32-bit as it is based on phys_addr_t which in turn is
> based on CONFIG_LPAE setting. However, the address sizes in DT are
> fixed and may be 64-bit. So we stick with u64 in the DT code.

I think I see your point about fdt_translate_address(); you want it to
mirror of_translate_address(), yes?  If so, then I have no objection
to this patch and will mark it reviewed.

But the u64 value from fdt_translate_address() should be preserved
at least to the ioremap()/set_fixmap() in earlycon_map() .
I could roll that change into my earlycon series that moves
fdt_translate_address() into of_setup_earlycon(), thus preserving
the u64 value until it's assigned to a phys_addr_t.

Regards,
Peter Hurley
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