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Message-ID: <1b260786-310c-4143-bf78-7afce33f05fe@quicinc.com>
Date: Thu, 2 May 2024 11:27:21 -0700
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Subject: Re: [PATCH v2 1/3] wifi: ath12k: prepare vif data structure for MLO
 handling
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To: Rameshkumar Sundaram <quic_ramess@quicinc.com>,
        <ath12k@lists.infradead.org>
CC: <linux-wireless@vger.kernel.org>, Sriram R <quic_srirrama@quicinc.com>
References: <20240502171240.927155-1-quic_ramess@quicinc.com>
 <20240502171240.927155-2-quic_ramess@quicinc.com>
From: Jeff Johnson <quic_jjohnson@quicinc.com>
In-Reply-To: <20240502171240.927155-2-quic_ramess@quicinc.com>
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On 5/2/2024 10:12 AM, Rameshkumar Sundaram wrote:
> From: Sriram R <quic_srirrama@quicinc.com>
> 
> To prepare the driver for MLO support, split the driver vif
> data structure to scale for multiple links. This requires changing
> the use of arvif to per link and not per hw which can now
> comprise of multiple links.
> Also since most configurations from mac80211 are done per link, do refactoring
> of the driver functions to apply these configurations at link level.
> 
> Split ath12k_vif which is the driver private of ieee80211_vif to store
> link specific information as ath12k_link_vif. For default use cases
> the ath12k vif will have a preallocated link vif called deflink which will
> be used by non ML and the first link vif of ML vif.
> 
> With MLO Support to be added, remaining link vifs will be allocated during
> channel assignment where vdev create/start happens. These link vifs will be
> freed during interface down.
> 
>        		Current ath12k_vif(arvif) structure
> 
>              +---------------+      +---------------+     +---------------+
>              | ieee80211_vif |      | ieee80211_vif |     | ieee80211_vif |
>              | private data  |      | private data  |     | private data  |
>              |               |      |               |     |               |
>              |  ath12k_vif   |      |  ath12k_vif   |     |  ath12k_vif   |
>              |  (arvif)      |      |  (arvif)      |     |  (arvif)      |
>              |               |      |               |     |               |
>              |  +----------+ |      |  +----------+ |     |  +----------+ |
>              |  |*ar (2GHz)| |      |  |*ar (5GHz)| |     |  |*ar (2GHz)| |
>              |  +----------+ |      |  +----------+ |     |  +----------+ |
>              |               |      |               |     |               |
>              +---------------+      +---------------+     +---------------+
> 
>        	Proposed ath12k_vif(ahvif) containing ath12k_link_vif(s) (arvif)
>        	(deflink is preallocated member which is always the first link if
>        	 ieee80211_vif is MLD and is the only link otherwise)
> 
>        			+---------------------------------+
>        			|     ieee80211_vif               |
>        			|     private data                |
>        			|                                 |
>        			|   ath12k_vif(ahvif)             |
>        			|                                 |
>        			| +-------------------------------+
>        			| |ath12k_link_vif deflink (arvif)|
>        			| |        +---------------+      |
>        			| |        | *ar(2GHz)     |      |
>        			| +-------------------------------+
>        			| +-------------------------------+
>        			| |  ath12k_link_vif *link (arvif)|
>        			| |        +---------------+      |
>        			| |        | *ar(5GHz)     |      |
>        			| +-------------------------------+
>        			| +-------------------------------+
>        			| |  ath12k_link_vif *link (arvif)|
>        			| |        +---------------+      |
>        			| |        | *ar(6GHz)     |      |
>        			| +-------------------------------+
>        			|                                 |
>        			+---------------------------------+
> 
> To refactor existing ath12k_vif to make use of link vifs, following
> changes are made,
> 
>  1. ath12k_vif now called by variable name ahvif stores multiple
>  arvifs(ah12k_link_vif) and also has a back pointer to ieee80211_vif.
> 
>  2. In this patch set, only deflink is used to be on par with the
>  existing code. When MLO support is added the link id will be used to
>  fetch the arvif.
> 
>  3. For mac80211 ops which doesn't use specific link_id, the config or info
>  is common for the vif, hence apply the config to all link vifs.
>  The links_map in the ahvif, will be used to identify all the link vifs that
>  are setup.
> 
>  4. Change ath12k_vif_to_arvif() as ath12k_vif_to_ahvif() to fetch the
>  hw level vif. The link vif can be fetched from ahvif->link[], or the
>  deflink can be accessed via ahvif->deflink. API to access link
>  vif(arvif) by passing link_id can be introduced with MLO Support.
> 
>  5. The ieee80211_vif can be accessed from ahvif using ath12k_vif_to_vif()
> 
> Locking:
>  Currently modifications to members of arvif and arsta are protected by ar->conf_mutex
>  and it stays as such.
>  Now with these hw level structure (ahvif) being introduced, any modifications
>  to its members and link objects (i.e., arvifs[] which are dynamically allocated)
>  needs to be protected for writing and ah->conf_mutex is used for the same.
>  Also, atomic contexts(say WMI events and certain mac_ops) that we currently have in driver
>  will not(shouldn't be allowed) do any modifications but can read them and
>  rcu_read_lock() is used for the same.
> 
> Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1
> Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3
> 
> Signed-off-by: Sriram R <quic_srirrama@quicinc.com>
> Co-developed-by: Rameshkumar Sundaram <quic_ramess@quicinc.com>
> Signed-off-by: Rameshkumar Sundaram <quic_ramess@quicinc.com>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>