Re: [PATCH v1 0/2] serial: 8250_pci: Split Pericom driver

[Jay Dolan]

On 11/21/21 2:16 AM, Andy Shevchenko wrote:
> On Sat, Nov 20, 2021 at 11:46 PM Jay Dolan <jay.dolan@xxxxxxxxxxx> wrote:
> > On 11/19/21 6:33 AM, Jay Dolan wrote:
> > > On 11/19/21 12:23 AM, Andy Shevchenko wrote:
> > > > On Thu, Nov 18, 2021 at 10:32:51PM -0800, Jay Dolan wrote:
> > > > > On 11/17/21 6:57 AM, Andy Shevchenko wrote:
>
> > > > > > Split Pericom driver to a separate module.
> > > > > > While at it, re-enable high baud rates.
> > > > > >
> > > > > > Jay, can you, please, test this on as many hardware as you have?
> > > > > >
> > > > > > The series depends on the fix-series:
> > > > > > https://lore.kernel.org/linux-serial/20211117145502.43645-1-andriy.shevchenko@xxxxxxxxxxxxxxx/T/#u
> > > >
> > > > > I have my current state here:
> > > > > https://github.com/accesio/linux/blob/split-pericom-driver/drivers/tty/serial/8250/8250_pericom.c
> > > > >
> > > > >
> > > > > * Change port type to UPIO_PORT
> > > > > * Add in pericom_do_startup() because the UPF_MAGIC_MULTIPLIER doesn't
> > > > > stick.
> > > >
> > > > Thanks, I have updated my local tree with these changes.
> > > >
> > > > > When I'm testing baud rates greater than baud_base I'm seeing strange
> > > > > things
> > > > > on the scope.
> > > >
> > > > Can you confirm that there are no issues with the first (fixes) series?
> > > Yes. The fixes series has no issues, and was tested up to baud_base for
> > > both 14 and 24 MHz crystals.
> > > > I have slightly changed your set_divisor() refactoring, it may be that
> > > > issue
> > > > is there.
> > > >
> > > > > Maybe I'm just tired, and it's human error. I should be able
> > > > > to get back to it and get it done on Saturday.
> > > >
> > > > Thank you.
> >
> > Latest code is still here
> > https://github.com/accesio/linux/blob/split-pericom-driver/drivers/tty/serial/8250/8250_pericom.c
> >
> > Changes from last update:
> > * Avoid divide by zero when initializing delta
>
> Thanks for digging into it. But doesn't it mean that the issue is in
> the fix series as I assumed before?
Yes. It just happens to not get hit at any of the standard baud rates 
that I found in the termbits.h files. So testing didn't find it until 
testing rates greater than what is allowed without the magic multiplier 
flag.
I found it when doing the math on 3000000 because that causes it with 
the 14 MHz crystal.
> > I retested and verified on the scope that speeds are now being set
> > correctly.
> >
> > I have also confirmed that all of the ACCES four port cards in the
> > driver do have the offset fourth port. The item I raised about PCI was a
> > misunderstanding that was all on my end.
>
> Good to know that is not relevant.
>
> > Are there any other action items I should be handling?
>
> I think I have to issue two new iterations of each series and collect
> your formal Tested-by on the second one.