On 04/23/2018 08:47 AM, Kalle Valo wrote:
Larry Finger <Larry.Finger@xxxxxxxxxxxx> writes:
On 04/20/2018 07:01 AM, Kalle Valo wrote:
<pkshih@xxxxxxxxxxx> writes:
From: Ping-Ke Shih <pkshih@xxxxxxxxxxx>
The module parameter ant_sel is used to control antenna number and path.
There is an existing enum ANT_{X2,X1} defined the antenna number, so
add a new enum ANT_{MAIN,AUX} to make it readable. After this work,
incorrect given values depend on ant_sel were exposed, so refill values
according following definition:
ant_sel ant_num ant_path print_label
1 ANT_X1 ANT_AUX #2
2 ANT_X2 ANT_MAIN #1
Then, a workaround resulted from the incorrect values in halbtcoutsrc.c was
removed. These is a existing bug in the workaround while ant_sel=2, but the
case is rare use so user is hard to observe this bug.
The experimental results with single antenna connected to specific path
are in following:
ant_sel ANT_MAIN(#1) ANT_AUX(#2)
0 -8 -62
1 -62 -10
2 -6 -60
Signed-off-by: Ping-Ke Shih <pkshih@xxxxxxxxxxx>
Cc: Stable <stable@xxxxxxxxxxxxxxx> # 4.7+
Reviewed-by: Larry Finger <Larry.Finger@xxxxxxxxxxxx>
---
v2: Add more description about fixed bugs in end of first paragraph.
Sorry, I still don't understand the bug you are fixing. It shouldn't
take more than one minute to understand a commit log.
I prose that you rewrite the commit log, or at least parts of if it.
When you are describing a bug don't talk about enums or source files,
that's an implementation detail, and instead talk how the bug looks like
from users point of view. For example:
"On HP laptop model 1234 with Realtex 4321 device users are supposed
to use ant_sel module parameter with value 77 to use the correct
antenna. But instead rtlwifi incorrectly chose antenna 88 with lower
transmit power and that caused packet loss. Fix it so that the user
gets better transmit power and..."
(that's of course all made up information as I don't know what the
actual bug is)
And after that you can write rtlwifi internals in the commit log as much
as you want :) But there needs to be a clear generic description of the
bug first and it needs to understandable in one read.
To make this faster I propose that you send the new commit log as a
reply to this mail and I can then comment faster.
Kalle,
As I have some responsibility in creating this mess, let me try to
write a new commit log. I hope this answers your questions.
Thanks,
Larry
====================================
Some HP laptops have only a single wifi antenna. This would not be a
problem except that they were shipped with an incorrectly encoded
EFUSE. It should have been possible to open the computer and transfer
the antenna connection to the other terminal except that such action
might void the warranty, and moving the antenna broke the Windows
driver. The fix was to add a module option that would override the
EFUSE encoding. That was done with commit c18d8f509571 ("rtlwifi:
rtl8723be: Add antenna select module parameter"). There was still a
problem with Bluetooth coexistence, which was addressed with commit
baa170229095 ("rtlwifi: btcoexist: Implement antenna selection").
There were still problems, thus there were commit 0ff78adeef11
("rtlwifi: rtl8723be: fix ant_sel code") and commit 6d6226928369
("rtlwifi: btcoexist: Fix antenna selection code"). Despite all these
attempts at fixing the problem, the code is not yet right. A proper
fix is important as there are now instances of laptops having
RTL8723DE chips with the same problem.
This looks better, thanks.
The module parameter ant_sel is used to control antenna number and path.
At present enum ANT_{X2,X1} is used to define the antenna number, but
this choice is not intuitive, thus change to a new enum ANT_{MAIN,AUX}
to make it more readable. This change showed examples where incorrect
values were used. It was also possible to remove a workaround in
halbtcoutsrc.c
The experimental results with single antenna connected to specific path
are now as follows:
ant_sel ANT_MAIN(#1) ANT_AUX(#2)
0 -8 -62
1 -62 -10
2 -6 -60
But after reading this I'm still not sure if users are supposed to do
anything. I guess they will continue using existing values with the
ant_sel module parameter and nothing changes in that regard?
If users have two antennas, or a vendor that correctly encoded the EFUSE, this
patch will change nothing for them. If they have the low-signal problem, then
their choice of a value for ant_sel should not change. At least we are now sure
that using that module option will provide correct operation.
Larry
