// Add Johannes for commenting on adding another nl80211 commands Kalle Valo <kvalo@xxxxxxxxxxxxxx> writes:> > Tony Chuang <yhchuang@xxxxxxxxxxx> writes: > > > Kalle Valo <kvalo@xxxxxxxxxxxxxx> writes: > > > >> <yhchuang@xxxxxxxxxxx> writes: > >> > >> > From: Yan-Hsuan Chuang <yhchuang@xxxxxxxxxxx> > >> > > >> > It is useful to fix the bit rate of TX packets. For example, if > >> > someone is measuring the TX power, or debugging with the issues > >> > of the TX throughput on the field. > >> > > >> > To set the value of fixed rate, one should input corresponding > >> > desc rate index (ex, 0x0b for DESC_RATE54M to fix at 54 Mbps). > >> > Set a value larger than DESC_RATE_MAX will disable fix rate, so > >> > the rate adaptive mechanism can resume to work. > >> > > >> > Example, > >> > To fix rate at MCS 1: > >> > echo 0x0d > /sys/kernel/debug/ieee80211/phy0/rtw88/fix_rate > >> > > >> > To not to fix rate: > >> > echo 0xff > /sys/kernel/debug/ieee80211/phy0/rtw88/fix_rate > >> > > >> > To know which rate was fixed at: > >> > cat /sys/kernel/debug/ieee80211/phy0/rtw88/fix_rate > >> > > >> > Signed-off-by: Yan-Hsuan Chuang <yhchuang@xxxxxxxxxxx> > >> > >> No way, debugfs is not a method for working around nl80211 and doing > >> whatever idea you come up with. The goal is that we have a generic > >> nl80211 command for all generic actions, like this one. And I think we > >> already have an nl80211 command for fixing the tx rate, right? > >> > > > > No, as I can see, there's no suitable nl80211 command that can achieve > > what I want. If you are saying about > NL80211_CMD_SET_TX_BITRATE_MASK, > > it's used to allow some rates. But actually the firmware has its own rate > > adaptive mechanism, so mask out the other rates does not mean the rate > > left will be chosen. Moreover, the hardware will choose a lower bit rate > > when retry, then the TX rate is not fixed at all. So the debugfs can disable > > the firmware's RA mechanism, also disable the TX rate fall back when retry. > > Both of them cannot be done by setting TX bitrate mask. > > I'm confused, here you talk about firmware implementation etc but I'm > just talking about replacing the fix_rate debugfs file to an nl80211 > command (for providing the fix_rate value). Can you clarify more why you > think nl80211 is not suitable? Oops, I thought that you wanted me to use the existing nl80211 command. Now I know that you think we can add a new nl80211 command to help drivers to fix the TX bitrate if necessary. If adding another nl80211 command for that is acceptable, I can work on this. But I need Johannes's comment if it's better to add a new nl80211 command or to expand the existing command (ex. NL80211_CMD_SET_TX_BITRATE_MASK). It looks like that adding a new nl80211 command will be better for me as expanding the existing one would have great impact on the already distributed drivers/user-tools. > > > I am sorry I need to add another debugfs for it, but to actually fix the TX > > bitrate, we really need another debugfs or module parameter. Because > > according to the design of the device there is not a good enough general > > command I can use to fix the TX rate. If there is a command that can fix > > the TX bitrate for me, please let me know, I can switch to it. > > Sorry, but I'm not yet convinced that a debugfs file is justified. > Fixing a transmit bitrate sounds like a very generic command, not > something which should be in debugfs. > Thanks. Yen-Hsuan
