linux-kernel - Re: [PATCH 1/1] drm/i915/hdcp: Simplify code in intel_hdcp_auth

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Message-ID: <87sg28a3xg.fsf@intel.com>
Date:   Thu, 27 May 2021 13:04:11 +0300
From:   Jani Nikula <jani.nikula@...ux.intel.com>
To:     Zhen Lei <thunder.leizhen@...wei.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx <intel-gfx@...ts.freedesktop.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Cc:     Zhen Lei <thunder.leizhen@...wei.com>
Subject: Re: [PATCH 1/1] drm/i915/hdcp: Simplify code in intel_hdcp_auth_downstream()

On Thu, 27 May 2021, Zhen Lei <thunder.leizhen@...wei.com> wrote:
> If intel_hdcp_validate_v_prime() has been successful within the allowed
> number of tries, we can directly call drm_dbg_kms() and "goto out" without
> jumping out of the loop and repeatedly judging whether the operation is
> successful. This can help us reduce an unnecessary if judgment. And it's
> a little clearer to read.

Generally I think the "happy day scenario" should be at the topmost
indentation level and not buried in the ifs with a goto exit.

BR,
Jani.

>
> No functional change.
>
> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
> ---
>  drivers/gpu/drm/i915/display/intel_hdcp.c | 24 ++++++++++-------------
>  1 file changed, 10 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_hdcp.c b/drivers/gpu/drm/i915/display/intel_hdcp.c
> index d8570e14fe60..c32a854eda66 100644
> --- a/drivers/gpu/drm/i915/display/intel_hdcp.c
> +++ b/drivers/gpu/drm/i915/display/intel_hdcp.c
> @@ -663,13 +663,13 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)
>  
>  	ret = shim->read_ksv_fifo(dig_port, num_downstream, ksv_fifo);
>  	if (ret)
> -		goto err;
> +		goto out;
>  
>  	if (drm_hdcp_check_ksvs_revoked(&dev_priv->drm, ksv_fifo,
>  					num_downstream) > 0) {
>  		drm_err(&dev_priv->drm, "Revoked Ksv(s) in ksv_fifo\n");
>  		ret = -EPERM;
> -		goto err;
> +		goto out;
>  	}
>  
>  	/*
> @@ -680,20 +680,16 @@ int intel_hdcp_auth_downstream(struct intel_connector *connector)
>  		ret = intel_hdcp_validate_v_prime(connector, shim,
>  						  ksv_fifo, num_downstream,
>  						  bstatus);
> -		if (!ret)
> -			break;
> -	}
> -
> -	if (i == tries) {
> -		drm_dbg_kms(&dev_priv->drm,
> -			    "V Prime validation failed.(%d)\n", ret);
> -		goto err;
> +		if (!ret) {
> +			drm_dbg_kms(&dev_priv->drm,
> +				    "HDCP is enabled (%d downstream devices)\n",
> +				    num_downstream);
> +			goto out;
> +		}
>  	}
>  
> -	drm_dbg_kms(&dev_priv->drm, "HDCP is enabled (%d downstream devices)\n",
> -		    num_downstream);
> -	ret = 0;
> -err:
> +	drm_dbg_kms(&dev_priv->drm, "V Prime validation failed.(%d)\n", ret);
> +out:
>  	kfree(ksv_fifo);
>  	return ret;
>  }

-- 
Jani Nikula, Intel Open Source Graphics Center