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

[Ray Jui]

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 at broadcom.com>
>>>>> ---
>>>>>   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.

>>>
>>> Ray
>>>
>>
>> Regards,
>>  Scott