linux-kernel - Re: [PATCH] drivers: soc: xilinx: fix firmware driver Kconfig dependency

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Date:   Thu, 9 Apr 2020 12:43:34 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Arnd Bergmann <arnd@...db.de>,
        Michal Simek <michal.simek@...inx.com>
Cc:     arm-soc <arm@...nel.org>, Rajan Vaja <rajan.vaja@...inx.com>,
        Jolly Shah <jolly.shah@...inx.com>,
        Tejas Patel <tejas.patel@...inx.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drivers: soc: xilinx: fix firmware driver Kconfig
 dependency

On 09. 04. 20 11:09, Arnd Bergmann wrote:
> On Thu, Apr 9, 2020 at 8:37 AM Michal Simek <michal.simek@...inx.com> wrote:
>>
>> On 08. 04. 20 17:52, Arnd Bergmann wrote:
>>> The firmware driver is optional, but the power driver depends on it,
>>> which needs to be reflected in Kconfig to avoid link errors:
>>>
>>> aarch64-linux-ld: drivers/soc/xilinx/zynqmp_power.o: in function `zynqmp_pm_isr':
>>> zynqmp_power.c:(.text+0x284): undefined reference to `zynqmp_pm_invoke_fn'
>>>
>>> The firmware driver can probably be allowed for compile-testing as
>>> well, so it's best to drop the dependency on the ZYNQ platform
>>> here and allow building as long as the firmware code is built-in.
>>>
>>> Fixes: ab272643d723 ("drivers: soc: xilinx: Add ZynqMP PM driver")
>>> Signed-off-by: Arnd Bergmann <arnd@...db.de>
>>> ---
>>>  drivers/soc/xilinx/Kconfig | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/soc/xilinx/Kconfig b/drivers/soc/xilinx/Kconfig
>>> index 223f1f9d0922..646512d7276f 100644
>>> --- a/drivers/soc/xilinx/Kconfig
>>> +++ b/drivers/soc/xilinx/Kconfig
>>> @@ -19,7 +19,7 @@ config XILINX_VCU
>>>
>>>  config ZYNQMP_POWER
>>>       bool "Enable Xilinx Zynq MPSoC Power Management driver"
>>> -     depends on PM && ARCH_ZYNQMP
>>> +     depends on PM && ZYNQMP_FIRMWARE
>>>       default y
>>>       select MAILBOX
>>>       select ZYNQMP_IPI_MBOX
>>> @@ -35,7 +35,7 @@ config ZYNQMP_POWER
>>>  config ZYNQMP_PM_DOMAINS
>>>       bool "Enable Zynq MPSoC generic PM domains"
>>>       default y
>>> -     depends on PM && ARCH_ZYNQMP && ZYNQMP_FIRMWARE
>>> +     depends on PM && ZYNQMP_FIRMWARE
>>>       select PM_GENERIC_DOMAINS
>>>       help
>>>         Say yes to enable device power management through PM domains
>>>
>>
>> The same issue is likely with others drivers dependencies too which
>> depends on ARCH_ZYNQMP.
>>
>> It means all drivers which includes "linux/firmware/xlnx-zynqmp.h" and
>> call zynqmp_pm_get_eemi_ops() should depend on ZYNQMP_FIRMWARE instead
>> of ARCH_ZYNQMP.
> 
> The only one I see that has a hard dependency on ARCH_ZYNQMP
> without allowing compile-testing at the moment is drivers/edac/synopsys_edac.c
> but that doesn't use the firmware interface.
> 
> What I see in the header are declarations for exported functions:
> 
> int zynqmp_pm_invoke_fn(u32 pm_api_id, u32 arg0, u32 arg1,
>                         u32 arg2, u32 arg3, u32 *ret_payload);
> #if IS_REACHABLE(CONFIG_ZYNQMP_FIRMWARE)
> const struct zynqmp_eemi_ops *zynqmp_pm_get_eemi_ops(void);
> #else
> static inline struct zynqmp_eemi_ops *zynqmp_pm_get_eemi_ops(void)
> {
>         return ERR_PTR(-ENODEV);
> }
> #endif
> 
> The second one already allows compile-testing by turning into an
> inline stub, but zynqmp_pm_invoke_fn() does not, and this is the
> one causing the problem here.
> 
> I still think my patch is a good fix for that issue, but if you want to
> handle both interfaces the same way, we can also do that, either
> removing the stub and using a proper dependency, or using
> the same stub trick for both.

I have really not a problem with your fix above because the patch which
was applied has started to remove dependencies on ARCH_ZYNQMP. It
shouldn't be there because the same interface is used for new Xilinx
Versal device.

That header has been reworked by patches from here.
(last one) http://lkml.kernel.org/r/20200318115452.GA2491827@kroah.com
that's why changes has to go on the top of it.

Anyway feel free to take it directly or I will take it and send you pull
request. But will also look at other dependencies to make sure that they
are correct.

Acked-by: Michal Simek <michal.simek@...inx.com>

Thanks,
Michal