netdev - Re: [PATCH net-next 3/4] ice: Add support for SMA control multiplexer

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Message-ID: <20211013161909.735f2f17@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Wed, 13 Oct 2021 16:19:09 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Tony Nguyen <anthony.l.nguyen@...el.com>
Cc:     davem@...emloft.net,
        Maciej Machnikowski <maciej.machnikowski@...el.com>,
        netdev@...r.kernel.org, richardcochran@...il.com,
        Sunitha Mekala <sunithax.d.mekala@...el.com>
Subject: Re: [PATCH net-next 3/4] ice: Add support for SMA control
 multiplexer

On Tue, 12 Oct 2021 09:31:52 -0700 Tony Nguyen wrote:
> From: Maciej Machnikowski <maciej.machnikowski@...el.com>
> 
> E810-T adapters have two external bidirectional SMA connectors and two
> internal unidirectional U.FL connectors. Multiplexing between U.FL and
> SMA and SMA direction is controlled using the PCA9575 expander.
> 
> Add support for the PCA9575 detection and control of the respective pins
> of the SMA/U.FL multiplexer using the GPIO AQ API.

> +static int
> +ice_get_pca9575_handle(struct ice_hw *hw, u16 *pca9575_handle)
> +{
> +	struct ice_aqc_get_link_topo *cmd;
> +	struct ice_aq_desc desc;
> +	int status;
> +	u8 idx;
> +
> +	if (!hw || !pca9575_handle)
> +		return -EINVAL;

Looks like purest form of defensive programming, please drop this.

> +bool ice_is_pca9575_present(struct ice_hw *hw)
> +{
> +	u16 handle = 0;
> +	int status;
> +
> +	if (!ice_is_e810t(hw))
> +		return false;
> +
> +	status = ice_get_pca9575_handle(hw, &handle);
> +	if (!status && handle)
> +		return true;
> +
> +	return false;
> +}

	return !status && handle;