linux-kernel - Re: [PATCH] drm/amd/display: Fix 32-bit divide error in wait_for_alt

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Message-ID: <f594d746-9eaf-76fe-d380-bb033cce06f8@amd.com>
Date:   Wed, 21 Aug 2019 16:40:15 +0000
From:   Harry Wentland <hwentlan@....com>
To:     Nathan Chancellor <natechancellor@...il.com>,
        "Wentland, Harry" <Harry.Wentland@....com>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        "Zhou, David(ChunMing)" <David1.Zhou@....com>
CC:     "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH] drm/amd/display: Fix 32-bit divide error in
 wait_for_alt_mode

On 2019-08-20 7:57 p.m., 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@...radead.org>
> Signed-off-by: Nathan Chancellor <natechancellor@...il.com>

Reviewed-by: Harry Wentland <harry.wentland@....com>

Harry

> ---
>  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;
>  }
>  
>