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Date: Tue, 31 May 2011 18:06:50 +0100
Message-ID: <BANLkTimv8_GYyMCH_M3Pyv9_5R+wvr8YpA@mail.gmail.com> (sfid-20110531_190655_131683_B1BBE0D0)
Subject: Re: [ath9k-devel] Override Minstrel HT RC to set an MCS bitrate (mask)
From: "M. A." <jdiq123@googlemail.com>
To: ath9k-devel@lists.ath9k.org, linux-wireless@vger.kernel.org
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Hi all,

I would be grateful if anyone can advise on setting/masking a fixed
MCS HT rate (ath9k) at runtime, as I am only able to mask legacy
rates..

If this is not yet implemented, can anyone please advise on how to
implement this as I am in urgent need of this functionality.

Thank you all in advance!


> On Tue, Mar 15, 2011 at 5:02 AM, Mohammed Shafi <shafi.ath9k@gmail.com> wrote:
>> On Tue, Mar 8, 2011 at 11:10 PM, M. A. <jdiq123@googlemail.com> wrote:
>>> Hi all,
>>>
>>> My question is how can I modify Minstrel HT rate control to be able to
>>> override it (by a boolean or otherwise) to select an MCS or specific
>>> rate index from user space (such that once set it driver will only try
>>> sending at that rate until unset then driver will resort back to
>>> Minstrel RC).
>>
>> I don't think we can fix the MCS rate index from user space, may be we
>> need a hack.
>> iw ?dev <devname> set bitrates [legacy-<2.4|5> <legacy rate in Mbps>*]
>> and this is only for legacy rates.
>>
>>
>>>
>>> I have been able to change other kernel parameters at runtime(echo
>>> /sys/kernel/debug/ieee80211/...) by passing them through (fops) to
>>> DebugFs. however I am unsure of what parameters to pass through in the
>>> case of MCS rate fixing and what modifications to the code are
>>> required to achieve this.
>>
>> don't know and I am not sure whether this can be easily done.
>>
>>>
>>>
>>> Also I have been told that these sections of code facilitate the
>>> masking of rates;
>>>
>>> =========================================================================
>>> include/net/cfg80211.h: cfg80211_bitrate_mask
>>> -------------------------------------------------------------------------------------------------------
>>> /*
>>> ?* cfg80211_bitrate_mask - masks for bitrate control
>>> ?*/
>>> struct cfg80211_bitrate_mask {
>>> ? ? ? ?struct {
>>> ? ? ? ? ? ? ? ?u32 legacy;
>>> ? ? ? ? ? ? ? ?/* TODO: add support for masking MCS rates; e.g.: */
>>> ? ? ? ? ? ? ? ?/* u8 mcs[IEEE80211_HT_MCS_MASK_LEN]; */
>>> ? ? ? ?} control[IEEE80211_NUM_BANDS];
>>> };
>>> -------------------------------------------------------------------------------------------------------
>>> net/mac80211/cfg.c ieee80211_set_bitrate_mask
>>> -------------------------------------------------------------------------------------------------------
>>> static int ieee80211_set_bitrate_mask(struct wiphy *wiphy,
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct net_device *dev,
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?const u8 *addr,
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?const struct cfg80211_bitrate_mask *mask)
>>> {
>>> ? ? ? ?struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
>>> ? ? ? ?struct ieee80211_local *local = wdev_priv(dev->ieee80211_ptr);
>>> ? ? ? ?int i;
>>>
>>> ? ? ? ?/*
>>> ? ? ? ? * This _could_ be supported by providing a hook for
>>> ? ? ? ? * drivers for this function, but at this point it
>>> ? ? ? ? * doesn't seem worth bothering.
>>> ? ? ? ? */
>>> ? ? ? ?if (local->hw.flags & IEEE80211_HW_HAS_RATE_CONTROL)
>>> ? ? ? ? ? ? ? ?return -EOPNOTSUPP;
>>>
>>>
>>> ? ? ? ?for (i = 0; i < IEEE80211_NUM_BANDS; i++)
>>> ? ? ? ? ? ? ? ?sdata->rc_rateidx_mask[i] = mask->control[i].legacy;
>>>
>>> ? ? ? ?return 0;
>>> }
>>> -------------------------------------------------------------------------------------------------------
>>> net/wireless/nl80211.c: nl80211_set_tx_bitrate_mask
>>> -------------------------------------------------------------------------------------------------------
>>> static int nl80211_set_tx_bitrate_mask(struct sk_buff *skb,
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? struct genl_info *info)
>>> {
>>> ? ? ? ?struct nlattr *tb[NL80211_TXRATE_MAX + 1];
>>> ? ? ? ?struct cfg80211_registered_device *rdev = info->user_ptr[0];
>>> ? ? ? ?struct cfg80211_bitrate_mask mask;
>>> ? ? ? ?int rem, i;
>>> ? ? ? ?struct net_device *dev = info->user_ptr[1];
>>> ? ? ? ?struct nlattr *tx_rates;
>>> ? ? ? ?struct ieee80211_supported_band *sband;
>>>
>>> ? ? ? ?if (info->attrs[NL80211_ATTR_TX_RATES] == NULL)
>>> ? ? ? ? ? ? ? ?return -EINVAL;
>>>
>>> ? ? ? ?if (!rdev->ops->set_bitrate_mask)
>>> ? ? ? ? ? ? ? ?return -EOPNOTSUPP;
>>>
>>> ? ? ? ?memset(&mask, 0, sizeof(mask));
>>> ? ? ? ?/* Default to all rates enabled */
>>> ? ? ? ?for (i = 0; i < IEEE80211_NUM_BANDS; i++) {
>>> ? ? ? ? ? ? ? ?sband = rdev->wiphy.bands[i];
>>> ? ? ? ? ? ? ? ?mask.control[i].legacy =
>>> ? ? ? ? ? ? ? ? ? ? ? ?sband ? (1 << sband->n_bitrates) - 1 : 0;
>>> ? ? ? ?}
>>>
>>> ? ? ? ?/*
>>> ? ? ? ? * The nested attribute uses enum nl80211_band as the index. This maps
>>> ? ? ? ? * directly to the enum ieee80211_band values used in cfg80211.
>>> ? ? ? ? */
>>> ? ? ? ?nla_for_each_nested(tx_rates, info->attrs[NL80211_ATTR_TX_RATES], rem)
>>> ? ? ? ?{
>>> ? ? ? ? ? ? ? ?enum ieee80211_band band = nla_type(tx_rates);
>>> ? ? ? ? ? ? ? ?if (band < 0 || band >= IEEE80211_NUM_BANDS)
>>> ? ? ? ? ? ? ? ? ? ? ? ?return -EINVAL;
>>> ? ? ? ? ? ? ? ?sband = rdev->wiphy.bands[band];
>>> ? ? ? ? ? ? ? ?if (sband == NULL)
>>> ? ? ? ? ? ? ? ? ? ? ? ?return -EINVAL;
>>> ? ? ? ? ? ? ? ?nla_parse(tb, NL80211_TXRATE_MAX, nla_data(tx_rates),
>>> ? ? ? ? ? ? ? ? ? ? ? ? ?nla_len(tx_rates), nl80211_txattr_policy);
>>> ? ? ? ? ? ? ? ?if (tb[NL80211_TXRATE_LEGACY]) {
>>> ? ? ? ? ? ? ? ? ? ? ? ?mask.control[band].legacy = rateset_to_mask(
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?sband,
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?nla_data(tb[NL80211_TXRATE_LEGACY]),
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?nla_len(tb[NL80211_TXRATE_LEGACY]));
>>> ? ? ? ? ? ? ? ? ? ? ? ?if (mask.control[band].legacy == 0)
>>> ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?return -EINVAL;
>>> ? ? ? ? ? ? ? ?}
>>> ? ? ? ?}
>>>
>>> ? ? ? ?return rdev->ops->set_bitrate_mask(&rdev->wiphy, dev, NULL, &mask);
>>> }
>>
>> As you see everything is for legacy thing and for MCS it's a TODO section.
>>
>>> ====================================================================================================================
>>>
>>>
>>> Any help is much appreciated!
>>>
>>> Thank you all very much
>>> _______________________________________________
>>> ath9k-devel mailing list
>>> ath9k-devel@lists.ath9k.org
>>> https://lists.ath9k.org/mailman/listinfo/ath9k-devel
>>>
>>
>