Re: [PATCH] arm64: dts: stingray: use NUM_SATA to configure number of sata ports
From: Scott Branden
Date: Thu Jun 14 2018 - 14:53:16 EST
On 18-06-13 03:06 PM, Rob Herring wrote:
On Wed, Jun 13, 2018 at 2:18 PM, Scott Branden
<scott.branden@xxxxxxxxxxxx> wrote:
Hi Rob,
Thanks for comment - reply inline.
On 18-06-13 12:31 PM, Florian Fainelli wrote:
On 06/12/2018 03:54 PM, Rob Herring wrote:
On Thu, Jun 7, 2018 at 12:53 PM, Scott Branden
<scott.branden@xxxxxxxxxxxx> wrote:
Hi Rob,
Could you please kindly comment on change below.
It allows board variants to be added easily via a simple define for
different number of SATA ports.
On 18-06-04 09:22 AM, Florian Fainelli wrote:
On 05/18/2018 11:34 AM, Scott Branden wrote:
Move remaining sata configuration to stingray-sata.dtsi and enable
ports based on NUM_SATA defined.
Now, all that needs to be done is define NUM_SATA per board.
Rob could you review this and let us know if this approach is okay or
not? Thank you!
Signed-off-by: Scott Branden <scott.branden@xxxxxxxxxxxx>
---
diff --git a/arch/arm64/boot/dts/broadcom/stingray/stingray-sata.dtsi
b/arch/arm64/boot/dts/broadcom/stingray/stingray-sata.dtsi
index 8c68e0c..7f6d176 100644
--- a/arch/arm64/boot/dts/broadcom/stingray/stingray-sata.dtsi
+++ b/arch/arm64/boot/dts/broadcom/stingray/stingray-sata.dtsi
@@ -43,7 +43,11 @@
interrupts = <GIC_SPI 321
IRQ_TYPE_LEVEL_HIGH>;
#address-cells = <1>;
#size-cells = <0>;
+#if (NUM_SATA > 0)
+ status = "okay";
+#else
status = "disabled";
+#endif
This only works if ports are contiguously enabled (0-N). You might not
care, but it is not a pattern that works in general.
Correct - all board designs that include this dtsi file follow such
commonality (ie. design with SATA0 first, etc). By having common board
designs it allows for commonality in dts files rather than duplicating
information everywhere. If somebody designs a bizarro board they are free
to create their own dts file of course.
And I'm not a fan
of C preprocessing in DT files in general beyond just defines for
single numbers.
The use of a define to specify the number of SATA ports in the board design
meets our requirements of being able to maintain many boards. We need a
method to specify the number of ports in the board design rather than
copying and pasting the information in many dts files. If you have an
alternative upstreamable mechanism to manage the configuration of many
boards without copy and paste that would be ideal?
Is this really the only problem with maintaining lots of boards? What
about all the other nodes that are conditionally enabled? Really, I
don't see the problem with 3 lines per node.
Yes - the problem with maintaining lots of boards is having to copy and
paste duplicated lines per nodes in many files which can be maintained
with a single define.
Does having an unused port enabled cause problems? If not, you could
handle it all at run-time and just shutdown ports which have no link.
You'd want to do that anyway for boards with a port, but is not
connected to a drive (except for hotplug capable ports).
SATA is not the only place we use defines. This is one change for
review to see if there are any "real" problems with doing it upstream
and get comment. All the board variations simply add a few defines and
don't need to do anything else using my approach. No out-of-tree
special tools or scripts required to generate dts files, no run-time
bootloader or kernel changes necessary.
Maybe we could add a property in /chosen that is a list of nodes to
enable and either the bootloader or kernel could update their
'status'. Or It could even be done in dtc perhaps with some
/directive/.
Sure, if it is a single line change needed through a "chosen" or
"directive" instead of a "define" that sounds fine. How would I do that
in the SATA example?
I am looking for an in-tree solution to managing the boards in a simpler
manner than what is available by cutting and pasting nodes in many files.
The use of the defines allows such without any special script or tool or
repo needing to be maintained out of tree.
Rob