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Subject: Re: [PATCH] mac80211: Store max_mtu in ieee80211_hw
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Wen Gong <wgong@codeaurora.org>, ath10k@lists.infradead.org
Cc:     linux-wireless@vger.kernel.org
Date:   Wed, 04 Sep 2019 09:03:54 +0200
In-Reply-To: <1567577743-27684-1-git-send-email-wgong@codeaurora.org>
References: <1567577743-27684-1-git-send-email-wgong@codeaurora.org>
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On Wed, 2019-09-04 at 14:15 +0800, Wen Gong wrote:
> Make it possibly for drivers to adjust the default mat_mtu
> by storing it in the hardware struct.
> 
> +++ b/net/mac80211/iface.c
> @@ -1877,7 +1877,10 @@ int ieee80211_if_add(struct ieee80211_local *local, const char *name,
>  
>  		/* MTU range: 256 - 2304 */
>  		ndev->min_mtu = 256;
> -		ndev->max_mtu = IEEE80211_MAX_DATA_LEN;
> +		if (local->hw.max_mtu)
> +			ndev->max_mtu = local->hw.max_mtu;
> +		else
> +			ndev->max_mtu = IEEE80211_MAX_DATA_LEN;

It seems (slightly) preferable to me to just initialize the value in
local->hw.max_mtu in alloc_hw(), so the driver can override it before
register_hw(), and then use it here unconditionally. Any particular
reason for it being this way?

johannes