Hello,
I received no comments for these in the last two weeks. I assume there
are no further objections and I can push the patches to master in about
a week so that the bug is fixed at least for 6.
Best regards
Christian
Am 27.01.22 um 13:25 schrieb Christian MAUDERER:
Hello,
again: What can I do to make the patches acceptable?
Best regards
Christian
Am 21.01.22 um 11:57 schrieb Christian MAUDERER:
Ping.
Am 18.01.22 um 12:22 schrieb Christian MAUDERER:
Hello,
I noted that I still have this patch set open. I first posted it in
August 2021 and later pinged it in September 2021. Both times no
conclusion has been found. I would like to finally finish this topic
and get the patches in an acceptable state. To simplify it a bit,
let's only discuss the following two:
* [PATCH rtems 2/2] termios: Pass number of sent chars to l_start
https://lists.rtems.org/pipermail/devel/2021-August/068892.html
* [PATCH rtems-libbsd] ppp: Fix transmitting data
https://lists.rtems.org/pipermail/devel/2021-August/068893.html
The third one (or rather first one) is a BSP specific optimization
and not necessary for the other two. I'll not push that together with
these two. I'll start a separate discussion for it as soon as we are
done with these two.
From my point of view, the best case would be to apply the patches
to master and 5. Back when I started the discussion I created tickets
for both:
https://devel.rtems.org/ticket/4493
https://devel.rtems.org/ticket/4494
@Gedare: In the following mail thread you asked about tests on
further BSPs:
https://lists.rtems.org/pipermail/devel/2021-August/068908.html
I now finally tested the patches on an i.MXRT BSP. PPP works with the
patches and doesn't work without them on that target. That's what I
expected. The patches are tested on three serial drivers now:
- ATSAM and i.MXRT: Don't work without patches. Work with them.
- SC16IS752: Works for small packets only without patches. Works well
with them.
@Chris: We had two open discussions:
1. A style topic:
https://lists.rtems.org/pipermail/devel/2021-August/068912.html
Like said there, I would prefer not to reformat the whole file as
long as we don't do that at least a bit automatic for most files.
2. A discussion about the direction and the necessary API change:
https://lists.rtems.org/pipermail/devel/2021-September/069468.html
Like I explained: That PPP bug exists basically on all BSPs.
Depending on how many bytes a serial driver can process in it's write
function, PPP works better or worse. My assumption is that at the
moment, the PPP runs only on BSPs where it is "well enough" that no
one noted the bug.
To fix that bug, the PPP needs the information how many characters
have been sent out. My patch set uses our RTEMS default path via
rtems_termios_dequeue_characters().
I'm not entirely happy that I had to change the API. But I didn't
find a better solution and the API is still compatible. It will only
trigger a warning if someone doesn't use that extra parameter. If you
have a better idea how the bug could be fixed, I'm open to adapt the
patches. But I need a suggestion what would be a better solution
because - like I said - I didn't find one.
Best regards
Christian
Am 12.08.21 um 13:41 schrieb Christian Mauderer:
Hello,
this set of patches fixes PPP. Basically the current implementation in
libbsd can't work with console drivers that can't buffer a lot of
characters. The pppstart() function just assumes that the low level
console write can send an arbitrary number of characters without
checking how many characters are actually send.
In the extreme case of the ATSAM interfaces (only one character can be
send at once) it's not even possible to establish a PPP connection with
that. For UARTS that have some FIFO establishing might work but bigger
packets won't go through. I opened tickets for 6 and 5 here:
https://devel.rtems.org/ticket/4493
https://devel.rtems.org/ticket/4494
I would like to apply the patches to both branches (5 and 6).
The solution I implemented in this patch set is the following: PPP
output processing is done in the line discipline function l_start (or
rather the function where l_start points to: pppstart). Our device
writes don't return how many characters have been sent. Instead, that
feedback is given via rtems_termios_dequeue(). Luckily that's the
function that calls the l_start function.
The RTEMS patch for termios extends the l_start function so that it
gets
the number of characters as a second argument. This extension shouldn't
be a problem for existing code. In the worst case it will trigger a
warning that the function doesn't match the pointer type. But in the
linked code, that additional argument will just be ignored.
The libbsd patch extends the pppstart function so that it then handles
that new information.
Patches belonging to this set:
* [PATCH rtems 1/2] bsps/atsam: Improve UART / USART tx performance
* [PATCH rtems 2/2] termios: Pass number of sent chars to l_start
* [PATCH rtems-libbsd] ppp: Fix transmitting data
Best regards
Christian
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