linux-kernel - Re: [PATCH] drm/amd/display: add a WARN() to irq service functions

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Message-ID: <ec75ba21-97e0-9479-8d87-46cc8032d44c@amd.com>
Date:   Mon, 17 Oct 2022 09:06:38 -0400
From:   Rodrigo Siqueira <Rodrigo.Siqueira@....com>
To:     Hamza Mahfooz <hamza.mahfooz@....com>
Cc:     Harry Wentland <harry.wentland@....com>,
        Leo Li <sunpeng.li@....com>,
        Alex Deucher <alexander.deucher@....com>,
        Christian König <christian.koenig@....com>,
        "Pan, Xinhui" <Xinhui.Pan@....com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Mario Limonciello <mario.limonciello@....com>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Alex Hung <alex.hung@....com>, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org
Subject: Re: [PATCH] drm/amd/display: add a WARN() to irq service functions

Hi Hamza,

On 10/14/22 11:31, Hamza Mahfooz wrote:
> Currently, if we encounter unimplemented functions, it is difficult to
> tell what caused them just by looking at dmesg and that is compounded by
> the fact that it is often hard to reproduce said issues. So, to have
> access to more detailed debugging information, add a WARN() to
> dal_irq_service_ack() and dal_irq_service_set() that only triggers when
> we encounter an unimplemented function.

Do you know the specific issue that triggered this unimplemented 
function? It might be useful to describe the situation in the commit 
message where you see this problem.

> 
> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@....com>
> ---
>   drivers/gpu/drm/amd/display/dc/irq/irq_service.c | 10 ++++++++--
>   1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
> index 7bad39bba86b..b895bdd8dc55 100644
> --- a/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
> +++ b/drivers/gpu/drm/amd/display/dc/irq/irq_service.c
> @@ -112,8 +112,11 @@ bool dal_irq_service_set(
>   
>   	dal_irq_service_ack(irq_service, source);
>   
> -	if (info->funcs && info->funcs->set)
> +	if (info->funcs && info->funcs->set) {
> +		WARN(info->funcs->set == dal_irq_service_dummy_set,
> +		     "%s: src: %d, st: %d\n", __func__, source, enable);
>   		return info->funcs->set(irq_service, info, enable);

Do you know if we may hit this condition multiple times?

> +	}
>   
>   	dal_irq_service_set_generic(irq_service, info, enable);
>   
> @@ -146,8 +149,11 @@ bool dal_irq_service_ack(
>   		return false;
>   	}
>   
> -	if (info->funcs && info->funcs->ack)
> +	if (info->funcs && info->funcs->ack) {
> +		WARN(info->funcs->ack == dal_irq_service_dummy_ack,
> +		     "%s: src: %d\n", __func__, source);
>   		return info->funcs->ack(irq_service, info);
> +	}
>   
>   	dal_irq_service_ack_generic(irq_service, info);
>   

Just for curiosity, did you run some IGT tests?

Thanks
Siqueira