possible regression with rs485 usage

possible regression with rs485 usage

[Radisson97]

Hi, i am new to this list because i have a strange problem.

We have an embedded board based on the omap3-design with a rs485.
With kernel 3.5 it works fine. Since 3.5 is ancient we are noe trying
to get a new kernel up an running what is 5.8.

I turns out that the rs485 has issues (it seems a lot of ppl have
the same issue also with other boards). We enable the rs485 via ioctl()
and nothing seems to work. Several restarts, playing with Marcin Niestroyj's
rs485config it suddenly works. (yes hardware is ok, works with older kernel).

Can someone give me a hind where i should search. I am not a kernel expert
and there have been a lot of small changes that i do not understand. I am pretty
sure that it is not a major issue (famous last words) but i am out of clue
where to search.

CU

Re: possible regression with rs485 usage

[Greg KH]

On Thu, Sep 05, 2024 at 10:15:12AM +0200, Radisson97@web.de wrote:
> Hi, i am new to this list because i have a strange problem.
> 
> We have an embedded board based on the omap3-design with a rs485.
> With kernel 3.5 it works fine. Since 3.5 is ancient we are noe trying
> to get a new kernel up an running what is 5.8.

Any specific reason why 5.8?  That too is ancient and obsolete and not
supported by anyone.

> I turns out that the rs485 has issues (it seems a lot of ppl have
> the same issue also with other boards). We enable the rs485 via ioctl()
> and nothing seems to work. Several restarts, playing with Marcin Niestroyj's
> rs485config it suddenly works. (yes hardware is ok, works with older kernel).

So it does work?

What exact hardware and drivers are you using?

And can you try a modern and supported kernel version please?  We can't
do anything with 5.8 :(

thanks,

greg k-h

Re: possible regression with rs485 usage

[Peter Radisson]

Am 05.09.24 um 10:25 schrieb Greg KH:
> On Thu, Sep 05, 2024 at 10:15:12AM +0200, Radisson97@web.de wrote:
>> Hi, i am new to this list because i have a strange problem.
>>
>> We have an embedded board based on the omap3-design with a rs485.
>> With kernel 3.5 it works fine. Since 3.5 is ancient we are noe trying
>> to get a new kernel up an running what is 5.8.
>
> Any specific reason why 5.8?  That too is ancient and obsolete and not
> supported by anyone.
>
it seems the last kernel where our system seems to work. We want the
system to work with the vanilla kernel in future, for now we would be
happy to have a workng system at all.

>> I turns out that the rs485 has issues (it seems a lot of ppl have
>> the same issue also with other boards). We enable the rs485 via ioctl()
>> and nothing seems to work. Several restarts, playing with Marcin Niestroyj's
>> rs485config it suddenly works. (yes hardware is ok, works with older kernel).
>
> So it does work?
instable to say politely, we do not understand why, (read: this error
makes no sense). it seems stop working in later versions.
>
> What exact hardware and drivers are you using?
>
Board vased on Omap3-design with
* AM3703 with twl4030
* cp210x
* Ax88796

> And can you try a modern and supported kernel version please?  We can't
> do anything with 5.8 :(
>
Its a stepstone, (s.o). We have contracted a companie to upgrade the
kernel but they had trouble getting the patches accepted (so i send the
Ax88796 patch to the -netdev ml but i could not figure out
if there where incorporated actualy)

> thanks,
>
> greg k-h

hope that helps,