linux-kernel - Re: [PATCH v2 00/13] serial: 8250

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Message-ID: <ZtsU0nfAFssevmmz@smile.fi.intel.com>
Date: Fri, 6 Sep 2024 17:42:26 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Parker Newman <parker@...est.io>
Cc: Parker Newman <pnewman@...necttech.com>, linux-kernel@...r.kernel.org,
	linux-serial@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>
Subject: Re: [PATCH v2 00/13] serial: 8250_exar: Clean up the driver

On Fri, Sep 06, 2024 at 10:33:54AM -0400, Parker Newman wrote:
> On Fri, 6 Sep 2024 17:24:44 +0300
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> > On Fri, Sep 06, 2024 at 09:51:41AM -0400, Parker Newman wrote:
> > > On Fri, 6 Sep 2024 15:46:51 +0300
> > > Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> > > > On Fri, May 03, 2024 at 02:33:03PM -0400, Parker Newman wrote:

...

> > > > Sorry for blast from the past, but I have some instersting information
> > > > for you. We now have spi-gpio and 93c46 eeprom drivers available to be
> > > > used from others via software nodes, can you consider updating your code
> > > > to replace custom bitbanging along with r/w ops by the instantiating the
> > > > respective drivers?
> > >
> > > Hi Andy,
> > > The Exar UARTs don't actually use MPIO/GPIO for the EEPROM.
> > > They have a dedicated "EEPROM interface" which is accessed by the
> > > REGB (0x8E) register. It is a very simple bit-bang interface though,
> > > one bit per signal.
> > >
> > > I guess in theory I could either add  GPIO wrapper to toggle these bits
> > > and use the spi-gpio driver but I am not sure if that really improves things?
> > > Maybe using the spi-bitbang driver directly is more appropriate?
> > > What do you think?
> >
> > Yes, spi-bitbang seems better in this case.
> 
> I will try to make some time to implement this... Or if someone else from the
> community wants to take this on in the mean time I am certainly happy to test
> and help out!

Sure, I shared this thought due to having lack of time to look myself,
but I prepared the above mentioned drivers to make them work in this case.
(If you are curios, see the Git history for the last few releases with
 --author="Andy Shevchenko")

-- 
With Best Regards,
Andy Shevchenko