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Subject: Re: [PATCH] drm/amd/display: Fix 32-bit divide error in
 wait_for_alt_mode
To:     Nathan Chancellor <natechancellor@gmail.com>,
        Harry Wentland <harry.wentland@amd.com>,
        Leo Li <sunpeng.li@amd.com>,
        Alex Deucher <alexander.deucher@amd.com>,
        =?UTF-8?Q?Christian_K=c3=b6nig?= <christian.koenig@amd.com>,
        "David (ChunMing) Zhou" <David1.Zhou@amd.com>
Cc:     amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <20190820235713.3429-1-natechancellor@gmail.com>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <fdb89dea-8da7-12af-fc73-aa3c13929e83@infradead.org>
Date:   Tue, 20 Aug 2019 20:44:11 -0700
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On 8/20/19 4:57 PM, Nathan Chancellor wrote:
> When building arm32 allyesconfig:
> 
> ld.lld: error: undefined symbol: __aeabi_uldivmod
>>>> referenced by dc_link.c
>>>> gpu/drm/amd/display/dc/core/dc_link.o:(wait_for_alt_mode) in archive drivers/built-in.a
>>>> referenced by dc_link.c
>>>> gpu/drm/amd/display/dc/core/dc_link.o:(wait_for_alt_mode) in archive drivers/built-in.a
> 
> time_taken_in_ns is of type unsigned long long so we need to use div_u64
> to avoid this error.
> 
> Fixes: b5b1f4554904 ("drm/amd/display: Enable type C hotplug")
> Reported-by: Randy Dunlap <rdunlap@infradead.org>
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested

Thanks.

> ---
>  drivers/gpu/drm/amd/display/dc/core/dc_link.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> index f2d78d7b089e..8634923b4444 100644
> --- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
> @@ -721,7 +721,7 @@ bool wait_for_alt_mode(struct dc_link *link)
>  			time_taken_in_ns = dm_get_elapse_time_in_ns(
>  				link->ctx, finish_timestamp, enter_timestamp);
>  			DC_LOG_WARNING("Alt mode entered finished after %llu ms\n",
> -				       time_taken_in_ns / 1000000);
> +				       div_u64(time_taken_in_ns, 1000000));
>  			return true;
>  		}
>  
> @@ -730,7 +730,7 @@ bool wait_for_alt_mode(struct dc_link *link)
>  	time_taken_in_ns = dm_get_elapse_time_in_ns(link->ctx, finish_timestamp,
>  						    enter_timestamp);
>  	DC_LOG_WARNING("Alt mode has timed out after %llu ms\n",
> -			time_taken_in_ns / 1000000);
> +			div_u64(time_taken_in_ns, 1000000));
>  	return false;
>  }
>  
> 


-- 
~Randy