Tomas Winkler wrote:
> On Mon, Mar 31, 2008 at 6:05 PM, Vladimir Koutny <vlado@xxxxxxxxxxx> wrote:
>> When associating to a b-only AP where there is no ERP IE, short preamble
>> mode is left at previous state (probably also protection mode). In this
>> case, disable protection and use short preamble mode as specified in
>> capability field. The same is done if capability field is changed on-the-fly.
>>
>
> Not sure that capability information elements can change on the fly.
Not sure about short_preamble field either, but ie. short_slot_time does
change (btw. this is not handled by mac80211 at all, so the driver has to
decode it itself).
> I've posted patch that passes the whole capability upon association to
> driver and driver can choose whether short preabmle MIGHT by used or
> not.
> AP my force stations to move to long preamble by issuing ERP IE.
>
> So I think this patch is redunant.
Still, the issue is that bss_conf->use_short_preamble contains wrong
value when associating to non-erp AP. So even with your patch, the driver
can't decide which preamble mode to use - ERP IE has higher priority than
capability field, but the driver can't tell from bss_conf if the ERP-based
values are valid or not.
Regards,
Vlado
>
>
>> Signed-off-by: Vladimir Koutny <vlado@xxxxxx>
>>
>> ---
>> diff --git a/net/mac80211/ieee80211_sta.c b/net/mac80211/ieee80211_sta.c
>> index 6fb179a..2b49852 100644
>> --- a/net/mac80211/ieee80211_sta.c
>> +++ b/net/mac80211/ieee80211_sta.c
>> @@ -353,14 +353,12 @@ static void ieee80211_sta_wmm_params(struct net_device *dev,
>> }
>> }
>>
>> -
>> -static u32 ieee80211_handle_erp_ie(struct ieee80211_sub_if_data *sdata,
>> - u8 erp_value)
>> +static u32 ieee80211_handle_protect_preamb(struct ieee80211_sub_if_data *sdata,
>> + bool use_protection,
>> + bool use_short_preamble)
>> {
>> struct ieee80211_bss_conf *bss_conf = &sdata->bss_conf;
>> struct ieee80211_if_sta *ifsta = &sdata->u.sta;
>> - bool use_protection = (erp_value & WLAN_ERP_USE_PROTECTION) != 0;
>> - bool use_short_preamble = (erp_value & WLAN_ERP_BARKER_PREAMBLE) == 0;
>> DECLARE_MAC_BUF(mac);
>> u32 changed = 0;
>>
>> @@ -391,6 +389,32 @@ static u32 ieee80211_handle_erp_ie(struct ieee80211_sub_if_data *sdata,
>> return changed;
>> }
>>
>> +static u32 ieee80211_handle_erp_ie(struct ieee80211_sub_if_data *sdata,
>> + u8 erp_value)
>> +{
>> + bool use_protection = (erp_value & WLAN_ERP_USE_PROTECTION) != 0;
>> + bool use_short_preamble = (erp_value & WLAN_ERP_BARKER_PREAMBLE) == 0;
>> +
>> + return ieee80211_handle_protect_preamb(sdata,
>> + use_protection, use_short_preamble);
>> +}
>> +
>> +static u32 ieee80211_handle_bss_capability(struct ieee80211_sub_if_data *sdata,
>> + struct ieee80211_sta_bss *bss)
>> +{
>> + u32 changed = 0;
>> +
>> + if (bss->has_erp_value)
>> + changed |= ieee80211_handle_erp_ie(sdata, bss->erp_value);
>> + else {
>> + u16 capab = bss->capability;
>> + changed |= ieee80211_handle_protect_preamb(sdata, false,
>> + (capab & WLAN_CAPABILITY_SHORT_PREAMBLE) != 0);
>> + }
>> +
>> + return changed;
>> +}
>> +
>> int ieee80211_ht_cap_ie_to_ht_info(struct ieee80211_ht_cap *ht_cap_ie,
>> struct ieee80211_ht_info *ht_info)
>> {
>> @@ -509,9 +533,7 @@ static void ieee80211_set_associated(struct net_device *dev,
>> local->hw.conf.channel->center_freq,
>> ifsta->ssid, ifsta->ssid_len);
>> if (bss) {
>> - if (bss->has_erp_value)
>> - changed |= ieee80211_handle_erp_ie(
>> - sdata, bss->erp_value);
>> + changed |= ieee80211_handle_bss_capability(sdata, bss);
>> ieee80211_rx_bss_put(dev, bss);
>> }
>>
>> @@ -2756,6 +2778,11 @@ static void ieee80211_rx_mgmt_beacon(struct net_device *dev,
>>
>> if (elems.erp_info && elems.erp_info_len >= 1)
>> changed |= ieee80211_handle_erp_ie(sdata, elems.erp_info[0]);
>> + else {
>> + u16 capab = le16_to_cpu(mgmt->u.beacon.capab_info);
>> + changed |= ieee80211_handle_protect_preamb(sdata, false,
>> + (capab & WLAN_CAPABILITY_SHORT_PREAMBLE) != 0);
>> + }
>>
>> if (elems.ht_cap_elem && elems.ht_info_elem &&
>> elems.wmm_param && local->ops->conf_ht &&
>> --
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