From: Kalle Valo <kvalo@codeaurora.org>
To: Tony Chuang <yhchuang@realtek.com>
Cc: Johannes Berg <johannes@sipsolutions.net>,
"linux-wireless\@vger.kernel.org"
<linux-wireless@vger.kernel.org>,
"briannorris\@chromium.org" <briannorris@chromium.org>
Subject: Re: [PATCH] rtw88: add debugfs to fix tx rate
Date: Tue, 17 Mar 2020 17:40:58 +0200 [thread overview]
Message-ID: <875zf3kn05.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <ce990869ebf0478d98cd7e8416b36289@realtek.com> (Tony Chuang's message of "Tue, 17 Mar 2020 10:32:58 +0000")
Tony Chuang <yhchuang@realtek.com> writes:
> // Add Johannes for commenting on adding another nl80211 commands
>
> Kalle Valo <kvalo@codeaurora.org> writes:>
>
>> Tony Chuang <yhchuang@realtek.com> writes:
>>
>> > Kalle Valo <kvalo@codeaurora.org> writes:
>> >
>> >> <yhchuang@realtek.com> writes:
>> >>
>> >> > From: Yan-Hsuan Chuang <yhchuang@realtek.com>
>> >> >
>> >> > 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@realtek.com>
>> >>
>> >> 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.
Either use an existing nl80211 command or add a new one if needed. For
me most important is that we don't add hacks to debugfs just for
avoiding using nl80211.
> 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).
_Why_ is NL80211_CMD_SET_TX_BITRATE_MASK not suitable for you? You keep
saying that but I have still figured out why exactly you think so.
Please clarify this in detail.
> 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.
What kind of great impact are you talking about? Please be specific so
that we don't need to guess.
--
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
next prev parent reply other threads:[~2020-03-17 15:41 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-13 6:51 [PATCH] rtw88: add debugfs to fix tx rate yhchuang
2020-03-13 10:33 ` Kalle Valo
2020-03-16 2:28 ` Tony Chuang
2020-03-17 7:10 ` Kalle Valo
2020-03-17 10:32 ` Tony Chuang
2020-03-17 15:40 ` Kalle Valo [this message]
2020-03-17 15:49 ` Ben Greear
2020-03-18 9:02 ` Tony Chuang
2020-03-20 13:05 ` Johannes Berg
2020-03-25 0:03 ` Brian Norris
2020-03-25 2:55 ` Tony Chuang
2020-03-25 5:16 ` Brian Norris
2020-03-25 5:54 ` Tony Chuang
2020-03-25 9:10 ` Johannes Berg
2020-03-25 15:52 ` Ben Greear
2020-03-25 18:14 ` Brian Norris
2020-05-25 9:07 ` Johannes Berg
2020-05-25 16:16 ` Ben Greear
2020-03-26 18:27 ` Brian Norris
2021-11-26 16:19 ` Kalle Valo
2021-11-29 2:25 ` Pkshih
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