[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[Gregory CLEMENT]

There is no crystal connected to the internal RTC on the Open Block
AX3. So let's disable it in order to prevent the kernel probing the
driver uselessly. Eventually this patches removes the following
warning message from the boot log:
"rtc-mv d0010300.rtc: internal RTC not ticking"

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Cc: <stable@vger.kernel.org> # v3.8 +
---
Hi,

I plan to add this patch to mvebu/fixes once the v4.1-rc1 will be
released. I don't expect much comments about it, but there is time
for them if needed until the next PR.

Thanks,

Gregory


 arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
index 0c76d9f05fd0..f4838ebd918b 100644
--- a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
+++ b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
@@ -105,6 +105,10 @@
 		};
 
 		internal-regs {
+			rtc at 10300 {
+				/* No crystal connected to the internal RTC */
+				status = "disabled";
+			};
 			serial at 12000 {
 				status = "okay";
 			};
-- 
2.1.0

[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[Andrew Lunn]

On Wed, Apr 15, 2015 at 12:40:47PM +0200, Gregory CLEMENT wrote:
> There is no crystal connected to the internal RTC on the Open Block
> AX3. So let's disable it in order to prevent the kernel probing the
> driver uselessly. Eventually this patches removes the following
> warning message from the boot log:
> "rtc-mv d0010300.rtc: internal RTC not ticking"

Hi Gregory

I've seen this as well with my device.

Acked-by: Andrew Lunn <andrew@lunn.ch>

	  Andrew

> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> Cc: <stable@vger.kernel.org> # v3.8 +
> ---
> Hi,
> 
> I plan to add this patch to mvebu/fixes once the v4.1-rc1 will be
> released. I don't expect much comments about it, but there is time
> for them if needed until the next PR.
> 
> Thanks,
> 
> Gregory
> 
> 
>  arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
> index 0c76d9f05fd0..f4838ebd918b 100644
> --- a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
> +++ b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
> @@ -105,6 +105,10 @@
>  		};
>  
>  		internal-regs {
> +			rtc at 10300 {
> +				/* No crystal connected to the internal RTC */
> +				status = "disabled";
> +			};
>  			serial at 12000 {
>  				status = "okay";
>  			};
> -- 
> 2.1.0
> 

[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[Thomas Petazzoni]

Dear Gregory CLEMENT,

On Wed, 15 Apr 2015 12:40:47 +0200, Gregory CLEMENT wrote:
> There is no crystal connected to the internal RTC on the Open Block
> AX3. So let's disable it in order to prevent the kernel probing the
> driver uselessly. Eventually this patches removes the following
> warning message from the boot log:
> "rtc-mv d0010300.rtc: internal RTC not ticking"
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> Cc: <stable@vger.kernel.org> # v3.8 +

If an external crystal is needed on the board for the internal RTC,
then shouldn't instead the RTC have status = "disabled" in the
SoC-level .dtsi, and each board enabling it in its own
specific .dts, like we do for all other hardware blocks that
require/use external components/connexions?

Or, because the AX3 appears to be the only board in this case, we
decide to factorize enabling the RTC in the .dtsi, and leave it as a
special case to handle in the AX3 .dts ?

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[Andrew Lunn]

On Thu, Apr 16, 2015 at 06:52:56AM +0200, Thomas Petazzoni wrote:
> Dear Gregory CLEMENT,
> 
> On Wed, 15 Apr 2015 12:40:47 +0200, Gregory CLEMENT wrote:
> > There is no crystal connected to the internal RTC on the Open Block
> > AX3. So let's disable it in order to prevent the kernel probing the
> > driver uselessly. Eventually this patches removes the following
> > warning message from the boot log:
> > "rtc-mv d0010300.rtc: internal RTC not ticking"
> > 
> > Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> > Cc: <stable@vger.kernel.org> # v3.8 +
> 
> If an external crystal is needed on the board for the internal RTC,
> then shouldn't instead the RTC have status = "disabled" in the
> SoC-level .dtsi, and each board enabling it in its own
> specific .dts, like we do for all other hardware blocks that
> require/use external components/connexions?
> 
> Or, because the AX3 appears to be the only board in this case, we
> decide to factorize enabling the RTC in the .dtsi, and leave it as a
> special case to handle in the AX3 .dts ?

Hi Thomas

Experience from Kirkwood is that the majority of boards use the
internal RTC. Not having a crystal is the exception. So think default
enabled makes sense.

The only side affect of having the RTC enabled when there is no
crystal is the warning message. It makes no difference to the active
RTC on the i2c bus, it becomes rtc0.

    Andrew

[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[Willy Tarreau]

On Wed, Apr 15, 2015 at 12:40:47PM +0200, Gregory CLEMENT wrote:
> There is no crystal connected to the internal RTC on the Open Block
> AX3. So let's disable it in order to prevent the kernel probing the
> driver uselessly. Eventually this patches removes the following
> warning message from the boot log:
> "rtc-mv d0010300.rtc: internal RTC not ticking"

Now I understand why I was getting this message. Everytime it booted
I thought to myself "I have to debug this thing", now I understand
better.

Thanks,
Willy

[PATCH] ARM: mvebu: armada-xp-openblocks-ax3-4: Disable internal RTC

[Gregory CLEMENT]

On 15/04/2015 12:40, Gregory CLEMENT wrote:
> There is no crystal connected to the internal RTC on the Open Block
> AX3. So let's disable it in order to prevent the kernel probing the
> driver uselessly. Eventually this patches removes the following
> warning message from the boot log:
> "rtc-mv d0010300.rtc: internal RTC not ticking"
> 
> Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
> Cc: <stable@vger.kernel.org> # v3.8 +


applied on mvebu/fixes with Andrew's acked-by

Thanks,

Gregory

> ---
> Hi,
> 
> I plan to add this patch to mvebu/fixes once the v4.1-rc1 will be
> released. I don't expect much comments about it, but there is time
> for them if needed until the next PR.
> 
> Thanks,
> 
> Gregory
> 
> 
>  arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
> index 0c76d9f05fd0..f4838ebd918b 100644
> --- a/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
> +++ b/arch/arm/boot/dts/armada-xp-openblocks-ax3-4.dts
> @@ -105,6 +105,10 @@
>  		};
>  
>  		internal-regs {
> +			rtc at 10300 {
> +				/* No crystal connected to the internal RTC */
> +				status = "disabled";
> +			};
>  			serial at 12000 {
>  				status = "okay";
>  			};
> 


-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com