DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B65C1208E4
Subject: Re: [PATCH] mac80211: allow hardware scan to fall back to software
To:     Johannes Berg <johannes@sipsolutions.net>,
        linux-wireless@vger.kernel.org
References: <20181018083547.23262-1-johannes@sipsolutions.net>
Cc:     Sushant Kumar Mishra <sushant2k1513@gmail.com>,
        Siva Rebbagondla <siva.rebbagondla@redpinesignals.com>,
        Siva Rebbagondla <siva8118@gmail.com>,
        Sanjay Kumar Konduri <sanjay.konduri@redpinesignals.com>,
        Prameela Rani Garnepudi <prameela.j04cs@gmail.com>,
        Sushant Kumar Mishra <sushant.mishra@redpinesignals.com>,
        Johannes Berg <johannes.berg@intel.com>
From:   Arend van Spriel <arend.vanspriel@broadcom.com>
Message-ID: <eba7f8e3-9b51-b82b-fdf6-d440214ec653@broadcom.com>
Date:   Thu, 18 Oct 2018 12:42:33 +0200
User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101
 Thunderbird/45.8.0
MIME-Version: 1.0
In-Reply-To: <20181018083547.23262-1-johannes@sipsolutions.net>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-wireless-owner@vger.kernel.org
Precedence: bulk

On 10/18/2018 10:35 AM, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
>
> In some cases, like in the rsi driver hardware scan offload, there
> may be scenarios in which hardware scan might not be available or
> desirable.
>
> Allow drivers to cope with this by letting them fall back to software
> scan by returning the special value 1 from the hardware scan method.
>
> Requested-by: Sushant Kumar Mishra <sushant2k1513@gmail.com>
> Requested-by: Siva Rebbagondla <siva.rebbagondla@redpinesignals.com>
> Signed-off-by: Johannes Berg <johannes.berg@intel.com>
> ---
>  include/net/mac80211.h |  5 +++++
>  net/mac80211/scan.c    | 22 ++++++++++++++++++----
>  2 files changed, 23 insertions(+), 4 deletions(-)
>
> diff --git a/include/net/mac80211.h b/include/net/mac80211.h
> index 71985e95d2d9..4631b3b6fc37 100644
> --- a/include/net/mac80211.h
> +++ b/include/net/mac80211.h
> @@ -3239,6 +3239,11 @@ enum ieee80211_reconfig_type {
>   *	When the scan finishes, ieee80211_scan_completed() must be called;
>   *	note that it also must be called when the scan cannot finish due to
>   *	any error unless this callback returned a negative error code.
> + *	This callback is also allowed to return the special return value 1,
> + *	this indicates that hardware scan isn't desirable right now and a
> + *	software scan should be done instead. A driver wishing to use this
> + *	capability must ensure its (hardware) scan capabilities aren't
> + *	advertised as more capable than mac80211's software scan is.

Hi Johannes,

Not sure what is meant by the last sentence. What does "more capable" 
mean? What are (or where to find) the mac80211 software scan capabilities?

Regards,
Arend