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In-Reply-To: <bc54d67-e573-9ecc-1650-7e7fc35f7897@linux.intel.com>
From:   Andy Shevchenko <andy.shevchenko@gmail.com>
Date:   Wed, 29 Jun 2022 11:51:13 +0200
Message-ID: <CAHp75VdsTjbEwocx4DAhMBM6nwKhuL3xgaJeZhV=ZhBPz3pdRw@mail.gmail.com>
Subject: Re: [PATCH 4/4] serial: 8250_dw: Rework ->serial_out() LCR write
 retry logic
To:     =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Cc:     "open list:SERIAL DRIVERS" <linux-serial@vger.kernel.org>,
        Greg KH <gregkh@linuxfoundation.org>,
        Jiri Slaby <jirislaby@kernel.org>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Jun 29, 2022 at 11:40 AM Ilpo J=C3=A4rvinen
<ilpo.jarvinen@linux.intel.com> wrote:
> On Wed, 29 Jun 2022, Andy Shevchenko wrote:
> > On Wed, Jun 29, 2022 at 10:47 AM Ilpo J=C3=A4rvinen
> > <ilpo.jarvinen@linux.intel.com> wrote:
> > > On Tue, 28 Jun 2022, Andy Shevchenko wrote:

...

> > > Eh, are you suggesting I should do write as a side-effect inside one =
of
> > > the iopoll.h macros? Because those available seem to only read?
> > >
> > > Or should I create another macro there which writes too?
> >
> > It seems to me that it would be a macro on top of iopoll's one which
> > will take an op read and op write arguments depending on the case.
>
> The thing is those iopoll macros don't return until the timeout is
> exhausted

It returns when the condition is true (in your case verify_lcr is OK).

> so I don't think I can reuse them easily for this task ("on top
> of iopoll's one")? That is, w/o some major side-effect hack (which is
> IMHO a no-go).

Basically what we need is a write-read type of polling.

With your current approach I don't like that retries assignment is
duplicated several times and decrement happens in the callee. What I'm
trying to suggest is to research alternatives.

--=20
With Best Regards,
Andy Shevchenko