linux-kernel - Re: [PATCH] drm/amd/powerplay: work around enum conversion warnings

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Message-ID: <20190708145430.GC43693@archlinux-epyc>
Date:   Mon, 8 Jul 2019 07:54:30 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Rex Zhu <rex.zhu@....com>, Evan Quan <evan.quan@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "David (ChunMing) Zhou" <David1.Zhou@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, Likun Gao <Likun.Gao@....com>,
        Huang Rui <ray.huang@....com>,
        Gui Chengming <Jack.Gui@....com>,
        Kevin Wang <kevin1.wang@....com>,
        Hawking Zhang <Hawking.Zhang@....com>,
        amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] drm/amd/powerplay: work around enum conversion warnings

Hi Arnd,

On Mon, Jul 08, 2019 at 03:57:06PM +0200, Arnd Bergmann wrote:
> A couple of calls to smu_get_current_clk_freq() and smu_force_clk_levels()
> pass constants of the wrong type, leading to warnings with clang-8:
> 
> drivers/gpu/drm/amd/amdgpu/../powerplay/vega20_ppt.c:995:39: error: implicit conversion from enumeration type 'PPCLK_e' to different enumeration type 'enum smu_clk_type' [-Werror,-Wenum-conversion]
>                 ret = smu_get_current_clk_freq(smu, PPCLK_SOCCLK, &now);
>                       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/amd/amdgpu/../powerplay/inc/amdgpu_smu.h:775:82: note: expanded from macro 'smu_get_current_clk_freq'
>         ((smu)->funcs->get_current_clk_freq? (smu)->funcs->get_current_clk_freq((smu), (clk_id), (value)) : 0)
> 
> I could not figure out what the purpose is of mixing the types
> like this and if it is written like this intentionally.
> Assuming this is all correct, adding an explict case is an
> easy way to shut up the warnings.
> 
> Fixes: bc0fcffd36ba ("drm/amd/powerplay: Unify smu handle task function (v2)")
> Fixes: 096761014227 ("drm/amd/powerplay: support sysfs to get socclk, fclk, dcefclk")
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

I sent a series last week for all of the clang warnings that were added
in this driver recently.

https://lore.kernel.org/lkml/20190704055217.45860-1-natechancellor@gmail.com/

I think it is safe to use the CLK enums from the expected type (from
what I could see from going down the code flow rabbit hole).

https://lore.kernel.org/lkml/20190704055217.45860-4-natechancellor@gmail.com/

https://lore.kernel.org/lkml/20190704055217.45860-7-natechancellor@gmail.com/

Cheers,
Nathan