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? > 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. -- https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
