linux-kernel - Re: [PATCH v2] drm/amd/display: add an ASSERT() to irq service functions

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Date:   Mon, 17 Oct 2022 11:57:43 -0400
From:   Harry Wentland <harry.wentland@....com>
To:     Hamza Mahfooz <hamza.mahfooz@....com>,
        amd-gfx@...ts.freedesktop.org
Cc:     Roman Li <roman.li@....com>, Leo Li <sunpeng.li@....com>,
        Rodrigo Siqueira <Rodrigo.Siqueira@....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>,
        Nicholas Kazlauskas <nicholas.kazlauskas@....com>,
        Mario Limonciello <mario.limonciello@....com>,
        Alan Liu <HaoPing.Liu@....com>, Alex Hung <alex.hung@....com>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] drm/amd/display: add an ASSERT() to irq service
 functions



On 2022-10-17 11:38, 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, for instance we
> have had reports of this condition being triggered when removing a
> secondary display that is setup in mirror mode and is connected using
> usb-c. So, to have access to more detailed debugging information, add an
> ASSERT() to dal_irq_service_ack() and dal_irq_service_set() that only
> triggers when we encounter an unimplemented function.
> 
> Signed-off-by: Hamza Mahfooz <hamza.mahfooz@....com>
> ---
> v2: detail specific instance that I'm interested in and use ASSERT()
>     instead of WARN().
> ---
>  .../gpu/drm/amd/display/dc/irq/irq_service.c    | 17 +++++++++++++++--
>  1 file changed, 15 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..3d6ab4fd25cb 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 +112,15 @@ bool dal_irq_service_set(
>  
>  	dal_irq_service_ack(irq_service, source);
>  
> -	if (info->funcs && info->funcs->set)
> +	if (info->funcs && info->funcs->set) {
> +		if (info->funcs->set == dal_irq_service_dummy_set)
> +			DC_LOG_WARNING("%s: src: %d, st: %d\n", __func__,
> +				       source, enable);
> +
> +		ASSERT(info->funcs->set != dal_irq_service_dummy_set);

I think you'll want the ASSERT inside the if block.

Harry

> +
>  		return info->funcs->set(irq_service, info, enable);
> +	}
>  
>  	dal_irq_service_set_generic(irq_service, info, enable);
>  
> @@ -146,8 +153,14 @@ bool dal_irq_service_ack(
>  		return false;
>  	}
>  
> -	if (info->funcs && info->funcs->ack)
> +	if (info->funcs && info->funcs->ack) {
> +		if (info->funcs->ack == dal_irq_service_dummy_ack)
> +			DC_LOG_WARNING("%s: src: %d\n", __func__, source);
> +
> +		ASSERT(info->funcs->ack != dal_irq_service_dummy_ack);
> +
>  		return info->funcs->ack(irq_service, info);
> +	}
>  
>  	dal_irq_service_ack_generic(irq_service, info);
>