diff mbox

sunxi: dts: add a note that memory size is adjusted by boot loader.

Message ID 1390572852-15027-1-git-send-email-ijc@hellion.org.uk (mailing list archive)
State New, archived
Headers show

Commit Message

Ian Campbell Jan. 24, 2014, 2:14 p.m. UTC
I had to spend a couple of minutes proving to myself that this was the case on
cubietruck, so add a comment to save the next guy some effort.

Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-sunxi@googlegroups.com
---
This patch applies cleanly against v3.13 and Hans' sunxi-devel branch.

A plausible alternative would be to pull the memory node out of the dtsi files
and into the board specific files. I didn't go straight to that since I'd have
to research all the various boards ;-)

I considered maing it "reg = <0 0>" but decided that having some sort of least
common denominator would let things work even if the bootloader were broken.
---
 arch/arm/boot/dts/sun4i-a10.dtsi  |    1 +
 arch/arm/boot/dts/sun5i-a10s.dtsi |    1 +
 arch/arm/boot/dts/sun5i-a13.dtsi  |    1 +
 arch/arm/boot/dts/sun6i-a31.dtsi  |    1 +
 arch/arm/boot/dts/sun7i-a20.dtsi  |    1 +
 5 files changed, 5 insertions(+)

Comments

Hans de Goede Jan. 24, 2014, 3:31 p.m. UTC | #1
Hi,

On 01/24/2014 03:14 PM, Ian Campbell wrote:
> I had to spend a couple of minutes proving to myself that this was the case on
> cubietruck, so add a comment to save the next guy some effort.

Seems like a good idea to me, one small nitpick though see comments inline.

> Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
> Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> Cc: Hans de Goede <hdegoede@redhat.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-sunxi@googlegroups.com
> ---
> This patch applies cleanly against v3.13 and Hans' sunxi-devel branch.
>
> A plausible alternative would be to pull the memory node out of the dtsi files
> and into the board specific files. I didn't go straight to that since I'd have
> to research all the various boards ;-)

That won't help, some boards ie the original cubieboard and the mele-a1000 come
in both 512 MB and 1024 MB versions, and I don't think we want to start maintaining
2 different dts files just for that.

>
> I considered maing it "reg = <0 0>" but decided that having some sort of least
> common denominator would let things work even if the bootloader were broken.
> ---
>   arch/arm/boot/dts/sun4i-a10.dtsi  |    1 +
>   arch/arm/boot/dts/sun5i-a10s.dtsi |    1 +
>   arch/arm/boot/dts/sun5i-a13.dtsi  |    1 +
>   arch/arm/boot/dts/sun6i-a31.dtsi  |    1 +
>   arch/arm/boot/dts/sun7i-a20.dtsi  |    1 +
>   5 files changed, 5 insertions(+)
>
> diff --git a/arch/arm/boot/dts/sun4i-a10.dtsi b/arch/arm/boot/dts/sun4i-a10.dtsi
> index 3e60883..9ba0beb 100644
> --- a/arch/arm/boot/dts/sun4i-a10.dtsi
> +++ b/arch/arm/boot/dts/sun4i-a10.dtsi
> @@ -30,6 +30,7 @@
>   	};
>
>   	memory {
> +		/* 1GB by default, will be updated by U-Boot */
>   		reg = <0x40000000 0x80000000>;
>   	};
>

The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
datasheet claims as max RAM.

> diff --git a/arch/arm/boot/dts/sun5i-a10s.dtsi b/arch/arm/boot/dts/sun5i-a10s.dtsi
> index 0376c50..d12ed7e 100644
> --- a/arch/arm/boot/dts/sun5i-a10s.dtsi
> +++ b/arch/arm/boot/dts/sun5i-a10s.dtsi
> @@ -27,6 +27,7 @@
>   	};
>
>   	memory {
> +		/* 512MB by default, will be updated by U-Boot */
>   		reg = <0x40000000 0x20000000>;
>   	};
>

This seems wrong (copy paste from A13 error) I've a10s boards with 1G, and the data
sheet claims 2GB max RAM.

> diff --git a/arch/arm/boot/dts/sun5i-a13.dtsi b/arch/arm/boot/dts/sun5i-a13.dtsi
> index b81aeb9..6f8bfd9 100644
> --- a/arch/arm/boot/dts/sun5i-a13.dtsi
> +++ b/arch/arm/boot/dts/sun5i-a13.dtsi
> @@ -27,6 +27,7 @@
>   	};
>
>   	memory {
> +		/* 512MB by default, will be updated by U-Boot */
>   		reg = <0x40000000 0x20000000>;
>   	};
>
> diff --git a/arch/arm/boot/dts/sun6i-a31.dtsi b/arch/arm/boot/dts/sun6i-a31.dtsi
> index 3f6f07b..bcbef9a 100644
> --- a/arch/arm/boot/dts/sun6i-a31.dtsi
> +++ b/arch/arm/boot/dts/sun6i-a31.dtsi
> @@ -46,6 +46,7 @@
>   	};
>
>   	memory {
> +		/* 2GB by default, will be updated by U-Boot */
>   		reg = <0x40000000 0x80000000>;
>   	};
>
> diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
> index 907cfcc..658e74b 100644
> --- a/arch/arm/boot/dts/sun7i-a20.dtsi
> +++ b/arch/arm/boot/dts/sun7i-a20.dtsi
> @@ -38,6 +38,7 @@
>   	};
>
>   	memory {
> +		/* 1GB by default, will be updated by U-Boot */
>   		reg = <0x40000000 0x80000000>;
>   	};

The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
datasheet claims as max RAM.

Regards,

Hans
Ian Campbell Jan. 24, 2014, 3:41 p.m. UTC | #2
On Fri, 2014-01-24 at 16:31 +0100, Hans de Goede wrote:
> Hi,
> 
> On 01/24/2014 03:14 PM, Ian Campbell wrote:
> > I had to spend a couple of minutes proving to myself that this was the case on
> > cubietruck, so add a comment to save the next guy some effort.
> 
> Seems like a good idea to me, one small nitpick though see comments inline.
> 
> > Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
> > Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
> > Cc: Hans de Goede <hdegoede@redhat.com>
> > Cc: linux-arm-kernel@lists.infradead.org
> > Cc: linux-sunxi@googlegroups.com
> > ---
> > This patch applies cleanly against v3.13 and Hans' sunxi-devel branch.
> >
> > A plausible alternative would be to pull the memory node out of the dtsi files
> > and into the board specific files. I didn't go straight to that since I'd have
> > to research all the various boards ;-)
> 
> That won't help, some boards ie the original cubieboard and the mele-a1000 come
> in both 512 MB and 1024 MB versions, and I don't think we want to start maintaining
> 2 different dts files just for that.

I didn't mean to suggest that u-boot should stop updating the dtb, so
e.g. I would have put a 512MB reg in the cubieboard dts, with a similar
comment.

But in cases where there is only one variant (e.g. the cubietruck) I'd
have put a 2GB reg and no comment, even though u-boot would in reality
rewrite the 2GB there. 

> > diff --git a/arch/arm/boot/dts/sun4i-a10.dtsi b/arch/arm/boot/dts/sun4i-a10.dtsi
> > index 3e60883..9ba0beb 100644
> > --- a/arch/arm/boot/dts/sun4i-a10.dtsi
> > +++ b/arch/arm/boot/dts/sun4i-a10.dtsi
> > @@ -30,6 +30,7 @@
> >   	};
> >
> >   	memory {
> > +		/* 1GB by default, will be updated by U-Boot */
> >   		reg = <0x40000000 0x80000000>;
> >   	};
> >
> 
> The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
> datasheet claims as max RAM.

Oops, I must have missed that.

> 
> > diff --git a/arch/arm/boot/dts/sun5i-a10s.dtsi b/arch/arm/boot/dts/sun5i-a10s.dtsi
> > index 0376c50..d12ed7e 100644
> > --- a/arch/arm/boot/dts/sun5i-a10s.dtsi
> > +++ b/arch/arm/boot/dts/sun5i-a10s.dtsi
> > @@ -27,6 +27,7 @@
> >   	};
> >
> >   	memory {
> > +		/* 512MB by default, will be updated by U-Boot */
> >   		reg = <0x40000000 0x20000000>;
> >   	};
> >
> 
> This seems wrong (copy paste from A13 error) I've a10s boards with 1G, and the data
> sheet claims 2GB max RAM.

I had expected these values to contain the minimum -- i.e. the one which
would work everywhere, so it would work if for some reason u-boot wasn't
updating correctly. Better to boot with only some of the RAM than to
crash randomly.

> > diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
> > index 907cfcc..658e74b 100644
> > --- a/arch/arm/boot/dts/sun7i-a20.dtsi
> > +++ b/arch/arm/boot/dts/sun7i-a20.dtsi
> > @@ -38,6 +38,7 @@
> >   	};
> >
> >   	memory {
> > +		/* 1GB by default, will be updated by U-Boot */
> >   		reg = <0x40000000 0x80000000>;
> >   	};
> 
> The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
> datasheet claims as max RAM.

Huh, that's the second time I got the wrong one, and I swear I was
paying attention to it as well!

Ian.
Hans de Goede Jan. 25, 2014, 11:03 a.m. UTC | #3
Hi,

On 01/24/2014 04:41 PM, Ian Campbell wrote:
> On Fri, 2014-01-24 at 16:31 +0100, Hans de Goede wrote:
>> Hi,
>>
>> On 01/24/2014 03:14 PM, Ian Campbell wrote:
>>> I had to spend a couple of minutes proving to myself that this was the case on
>>> cubietruck, so add a comment to save the next guy some effort.
>>
>> Seems like a good idea to me, one small nitpick though see comments inline.
>>
>>> Signed-off-by: Ian Campbell <ijc@hellion.org.uk>
>>> Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
>>> Cc: Hans de Goede <hdegoede@redhat.com>
>>> Cc: linux-arm-kernel@lists.infradead.org
>>> Cc: linux-sunxi@googlegroups.com
>>> ---
>>> This patch applies cleanly against v3.13 and Hans' sunxi-devel branch.
>>>
>>> A plausible alternative would be to pull the memory node out of the dtsi files
>>> and into the board specific files. I didn't go straight to that since I'd have
>>> to research all the various boards ;-)
>>
>> That won't help, some boards ie the original cubieboard and the mele-a1000 come
>> in both 512 MB and 1024 MB versions, and I don't think we want to start maintaining
>> 2 different dts files just for that.
>
> I didn't mean to suggest that u-boot should stop updating the dtb, so
> e.g. I would have put a 512MB reg in the cubieboard dts, with a similar
> comment.

Hmm, I've no idea what the default / preferred way of handling this is,
I assume Maxime knows, so lets wait for his input on this.

> But in cases where there is only one variant (e.g. the cubietruck) I'd
> have put a 2GB reg and no comment, even though u-boot would in reality
> rewrite the 2GB there.
>
>>> diff --git a/arch/arm/boot/dts/sun4i-a10.dtsi b/arch/arm/boot/dts/sun4i-a10.dtsi
>>> index 3e60883..9ba0beb 100644
>>> --- a/arch/arm/boot/dts/sun4i-a10.dtsi
>>> +++ b/arch/arm/boot/dts/sun4i-a10.dtsi
>>> @@ -30,6 +30,7 @@
>>>    	};
>>>
>>>    	memory {
>>> +		/* 1GB by default, will be updated by U-Boot */
>>>    		reg = <0x40000000 0x80000000>;
>>>    	};
>>>
>>
>> The comment says 1GB, but the range says 2GB, note 2GB is consistent with what the
>> datasheet claims as max RAM.
>
> Oops, I must have missed that.
>
>>
>>> diff --git a/arch/arm/boot/dts/sun5i-a10s.dtsi b/arch/arm/boot/dts/sun5i-a10s.dtsi
>>> index 0376c50..d12ed7e 100644
>>> --- a/arch/arm/boot/dts/sun5i-a10s.dtsi
>>> +++ b/arch/arm/boot/dts/sun5i-a10s.dtsi
>>> @@ -27,6 +27,7 @@
>>>    	};
>>>
>>>    	memory {
>>> +		/* 512MB by default, will be updated by U-Boot */
>>>    		reg = <0x40000000 0x20000000>;
>>>    	};
>>>
>>
>> This seems wrong (copy paste from A13 error) I've a10s boards with 1G, and the data
>> sheet claims 2GB max RAM.
>
> I had expected these values to contain the minimum -- i.e. the one which
> would work everywhere, so it would work if for some reason u-boot wasn't
> updating correctly. Better to boot with only some of the RAM than to
> crash randomly.

Then all the other values would be wrong, we've A10 boards with only 512M, A13
boards with only 256, etc.

Anyways as said before lets wait for Maxime's input on this.

Regards,

Hans
Maxime Ripard Jan. 27, 2014, 2:57 p.m. UTC | #4
Hi Ian, Hans,

On Sat, Jan 25, 2014 at 12:03:16PM +0100, Hans de Goede wrote:
> Hmm, I've no idea what the default / preferred way of handling this is,
> I assume Maxime knows, so lets wait for his input on this.

I got the habit of setting the memory node to the max size the RAM
controller can handle from previous work on imx, but I don't really
have a preferrence here.

If that confuses people, we can just remove it from the DTSI
altogether. It will be patched by u-boot anyway, and we won't have to
create DTS variants this way.

Just don't do it for the A31 for the moment, since we don't have
DT-enabled u-boot for now.

Thanks!
Maxime
Ian Campbell Jan. 27, 2014, 3:52 p.m. UTC | #5
On Mon, 2014-01-27 at 15:57 +0100, Maxime Ripard wrote:
> Hi Ian, Hans,
> 
> On Sat, Jan 25, 2014 at 12:03:16PM +0100, Hans de Goede wrote:
> > Hmm, I've no idea what the default / preferred way of handling this is,
> > I assume Maxime knows, so lets wait for his input on this.
> 
> I got the habit of setting the memory node to the max size the RAM
> controller can handle from previous work on imx,

I suppose this has the advantage of being static for a given SoC, so
there is no question of what the smallest possible value is, even if it
has the disadvantage of not working as a default on many platforms
(perhaps I'm overestimating the utility of that?).

>  but I don't really
> have a preferrence here.
> 
> If that confuses people, we can just remove it from the DTSI
> altogether. It will be patched by u-boot anyway, and we won't have to
> create DTS variants this way.

I've occasionally seen issues with u-boot not expanding the fdt itself,
so the placeholder serves the purpose of letting it update without
expanding. That was in my more complex Xen boot script which use "fdt
set" a lot -- probably doesn't apply to properly integrated
functionality like updating the memory node? (Or if it does that's a
u-boot bug).

> Just don't do it for the A31 for the moment, since we don't have
> DT-enabled u-boot for now.

Ack!

Ian.
diff mbox

Patch

diff --git a/arch/arm/boot/dts/sun4i-a10.dtsi b/arch/arm/boot/dts/sun4i-a10.dtsi
index 3e60883..9ba0beb 100644
--- a/arch/arm/boot/dts/sun4i-a10.dtsi
+++ b/arch/arm/boot/dts/sun4i-a10.dtsi
@@ -30,6 +30,7 @@ 
 	};
 
 	memory {
+		/* 1GB by default, will be updated by U-Boot */
 		reg = <0x40000000 0x80000000>;
 	};
 
diff --git a/arch/arm/boot/dts/sun5i-a10s.dtsi b/arch/arm/boot/dts/sun5i-a10s.dtsi
index 0376c50..d12ed7e 100644
--- a/arch/arm/boot/dts/sun5i-a10s.dtsi
+++ b/arch/arm/boot/dts/sun5i-a10s.dtsi
@@ -27,6 +27,7 @@ 
 	};
 
 	memory {
+		/* 512MB by default, will be updated by U-Boot */
 		reg = <0x40000000 0x20000000>;
 	};
 
diff --git a/arch/arm/boot/dts/sun5i-a13.dtsi b/arch/arm/boot/dts/sun5i-a13.dtsi
index b81aeb9..6f8bfd9 100644
--- a/arch/arm/boot/dts/sun5i-a13.dtsi
+++ b/arch/arm/boot/dts/sun5i-a13.dtsi
@@ -27,6 +27,7 @@ 
 	};
 
 	memory {
+		/* 512MB by default, will be updated by U-Boot */
 		reg = <0x40000000 0x20000000>;
 	};
 
diff --git a/arch/arm/boot/dts/sun6i-a31.dtsi b/arch/arm/boot/dts/sun6i-a31.dtsi
index 3f6f07b..bcbef9a 100644
--- a/arch/arm/boot/dts/sun6i-a31.dtsi
+++ b/arch/arm/boot/dts/sun6i-a31.dtsi
@@ -46,6 +46,7 @@ 
 	};
 
 	memory {
+		/* 2GB by default, will be updated by U-Boot */
 		reg = <0x40000000 0x80000000>;
 	};
 
diff --git a/arch/arm/boot/dts/sun7i-a20.dtsi b/arch/arm/boot/dts/sun7i-a20.dtsi
index 907cfcc..658e74b 100644
--- a/arch/arm/boot/dts/sun7i-a20.dtsi
+++ b/arch/arm/boot/dts/sun7i-a20.dtsi
@@ -38,6 +38,7 @@ 
 	};
 
 	memory {
+		/* 1GB by default, will be updated by U-Boot */
 		reg = <0x40000000 0x80000000>;
 	};