Re: [PATCH v2 0/7] sandbox: add gpio support with libftdi1

[Antony Pavlov <antonynpavlov@gmail.com>]

On Fri, 19 Jan 2018 10:40:08 +0100
Sascha Hauer <s.hauer@pengutronix.de> wrote:

> On Fri, Jan 19, 2018 at 12:29:01PM +0300, Antony Pavlov wrote:
> > On Wed, 17 Jan 2018 10:53:14 +0100
> > Sascha Hauer <s.hauer@pengutronix.de> wrote:
> > 
> > > Hi Antony,
> > > 
> > > On Mon, Jan 15, 2018 at 12:22:45AM +0300, Antony Pavlov wrote:
> > > > This patch series makes it possible to use FT2232H ACBUS[7:0]
> > > > pins as gpio pins from sandbox barebox.
> > > > 
> > > > There are ready-to-use FT2232H-based boards:
> > > > 
> > > >   * FT2232H-56Q Mini-Module (http://www.ftdichip.com/Products/Modules/DevelopmentModules.htm#FT2232H-56_Mini)
> > > >   * FT2232 breakout board (http://dangerousprototypes.com/docs/FT2232_breakout_board)
> > > > 
> > > > The main goal of adding gpio functionality to sandbox barebox
> > > > is using it for connecting real i2c and spi devices to sandbox barebox.
> > > 
> > > I applied the parseopt patches for now since they don't need any further
> > > discussions.
> > > 
> > 
> > There are three common parseopt-related patches:
> > 
> >   move parseopt to lib/
> >   include/parseopt.h: add guard macro
> >   parseopt: introduce parseopt_u16() and parseopt_str()
> > 
> > Please confirm that you have got all three patches.
> > 
> > > What puzzles me a bit is that the libftdi gpio controller is
> > > instantiated from the device tree but configured through the
> > > commandline. It probably has to be like this since we need the
> > > device tree for using the gpios.
> > 
> > Getting FTDI chip vendorID and deviceID from device tree is reasonable.
> > However hardcoding FTDI chip serialnumber into device tree is not so good idea.
> > In addition dropping cmdline FTDI options parsing makes parseopt_u16() and parseopt_str() unused.
> > 
> > I propose add FTDI chip vendorID, deviceID and serial options to device tree
> > and keep parsing the same options from cmdline so once can override FTDI chip
> > serial number from cmdline.
> 
> How would you handle multiple FTDI chips then if you want to make use
> of more than one at a time?

Good question. My current code gives no good means to add more than one FT2232 chip.
I suppose that after adding option-passing-via-dt feature it will be possible 
to add more than one FT2232 chip and ... cmdline option passing will interfere with
multi-FT2232 dt in a bad way. Now I think that dropping cmdline parsing is not so bad idea.

> 
> Sascha
> 
> 
> -- 
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-- 
Best regards,
  Antony Pavlov

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