Re: [PATCH v3 08/10] clk: ns2: add clock support for Broadcom Northstar 2 SoC

From: Scott Branden
Date: Thu Oct 15 2015 - 17:26:21 EST

On 15-10-15 02:15 PM, Ray Jui wrote:


On 10/15/2015 2:10 PM, Jon Mason wrote:
On Thu, Oct 15, 2015 at 02:04:09PM -0700, Scott Branden wrote:
Hi Ray,

Comment at near end.

On 15-10-15 01:55 PM, Ray Jui wrote:


On 10/15/2015 1:40 PM, Scott Branden wrote:
We need some sort of kconfig option to differentiate NS2 clock driver
>from being pulled in all the time.

On 15-10-15 12:48 PM, Jon Mason wrote:
The Broadcom Northstar 2 SoC is architected under the iProc
architecture. It has the following PLLs: GENPLL SCR, GENPLL SW,
LCPLL DDR, LCPLL Ports, all derived from an onboard crystal.

Signed-off-by: Jon Mason <jonmason@xxxxxxxxxxxx>
---
drivers/clk/Makefile | 2 +-
drivers/clk/bcm/Makefile | 1 +
drivers/clk/bcm/clk-ns2.c | 288
++++++++++++++++++++++++++++++++++++
include/dt-bindings/clock/bcm-ns2.h | 72 +++++++++
4 files changed, 362 insertions(+), 1 deletion(-)
create mode 100644 drivers/clk/bcm/clk-ns2.c
create mode 100644 include/dt-bindings/clock/bcm-ns2.h

diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index d08b3e5..6124bd3 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -47,7 +47,7 @@ obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
obj-$(CONFIG_COMMON_CLK_XGENE) += clk-xgene.o
obj-$(CONFIG_COMMON_CLK_PWM) += clk-pwm.o
obj-$(CONFIG_COMMON_CLK_AT91) += at91/
-obj-$(CONFIG_ARCH_BCM) += bcm/
+obj-y += bcm/
obj-$(CONFIG_ARCH_BERLIN) += berlin/
obj-$(CONFIG_ARCH_HISI) += hisilicon/
obj-$(CONFIG_ARCH_MXC) += imx/
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index e258b28..2d1cbc5 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_CLK_BCM_KONA) += clk-kona-setup.o
obj-$(CONFIG_CLK_BCM_KONA) += clk-bcm281xx.o
obj-$(CONFIG_CLK_BCM_KONA) += clk-bcm21664.o
obj-$(CONFIG_COMMON_CLK_IPROC) += clk-iproc-armpll.o
clk-iproc-pll.o clk-iproc-asiu.o
+obj-$(CONFIG_COMMON_CLK_IPROC) += clk-ns2.o

NS2 code is dragged in for all IPROC SoCs. We need a config option for
NS2 (CONFIG_ARCH_BCM_NS2) to avoid this (if Arnd allows this for ARMv8
processors... ?).

You can see below ARMv7 processors don't have this problem.


The arm64 maintainers (Catalin, Mark, and etc.) stated they only want
one ARCH options per chip family.

If not we need to add CONFIG_CLK_NS2.

If using CONFIG_CLK_NS2, how is it going to be enabled/selected?

Since CONFIG_ARCH_BCM_NS2 isn't "allowed" to be introduced we will
need to create and select a CONFIG_CLK_BCM_NS2 in the defconfig
instead.

Is this better than the binary becoming slightly bigger? I thought
the extra complexity was worse than having an unused chunk of clk code
(and Kona is already doing the same thing above). I believe Ray was
in agreement with me during the internal review of this code.

Thanks,
Jon


Yes, I'm okay with leaving it as it is. I even prefer changing the
current Makefile to make all iProc based core clock drivers and SoC
specific clock tables under CONFIG_COMMON_CLK_IPROC, which is what some
of the other vendors do.

I'd leave it exactly as is then rather than pulling in more dead code when not needed. This ns2 clock code is very minor compared to other code bloat in the kernel and drivers.

Ray


Regards,
Scott

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