[PATCH] drm/i915/alpm: Check for alpm support before accessing alpm register

[Cavitt, Jonathan]

-----Original Message-----
From: Intel-xe <intel-xe-bounces at lists.freedesktop.org> On Behalf Of Animesh Manna
Sent: Friday, April 25, 2025 6:21 AM
To: intel-gfx at lists.freedesktop.org; intel-xe at lists.freedesktop.org
Cc: Hogander, Jouni <jouni.hogander at intel.com>; Manna, Animesh <animesh.manna at intel.com>
Subject: [PATCH] drm/i915/alpm: Check for alpm support before accessing alpm register
> 
> Currently as EDP only support alpm and check for alpm support will
> prevent DP connector to access alpm register.

I'd maybe reword this as:
"""
Currently, only EDP supports alpm.  So, check for alpm support and
prevent the DP connector from accessing the alpm register if doing
so is unsupported.
"""
I won't block on the reword, however.  As is, this patch is
Reviewed-by: Jonathan Cavitt <jonathan.cavitt at intel.com>
-Jonathan Cavitt

> 
> Signed-off-by: Animesh Manna <animesh.manna at intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_alpm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_alpm.c b/drivers/gpu/drm/i915/display/intel_alpm.c
> index 482dd192d47d..1bf08b80c23f 100644
> --- a/drivers/gpu/drm/i915/display/intel_alpm.c
> +++ b/drivers/gpu/drm/i915/display/intel_alpm.c
> @@ -556,7 +556,7 @@ void intel_alpm_disable(struct intel_dp *intel_dp)
>  	struct intel_display *display = to_intel_display(intel_dp);
>  	enum transcoder cpu_transcoder = intel_dp->alpm_parameters.transcoder;
>  
> -	if (DISPLAY_VER(display) < 20)
> +	if (DISPLAY_VER(display) < 20 || !intel_dp->alpm_dpcd)
>  		return;
>  
>  	mutex_lock(&intel_dp->alpm_parameters.lock);
> -- 
> 2.29.0
> 
>