[PATCH v4 2/2] drivers: serial: probe all uart devices

[Vabhav Sharma (OSS)]

> -----Original Message-----
> From: Sean Anderson <seanga2 at gmail.com>
> Sent: Thursday, November 19, 2020 9:01 AM
> To: Vabhav Sharma (OSS) <vabhav.sharma at oss.nxp.com>;
> sjg at chromium.org; sr at denx.de
> Cc: u-boot at lists.denx.de; Varun Sethi <V.Sethi at nxp.com>;
> andre.przywara at arm.com; Vabhav Sharma <vabhav.sharma at nxp.com>
> Subject: Re: [PATCH v4 2/2] drivers: serial: probe all uart devices
> 
> On 11/17/20 10:00 AM, Vabhav Sharma wrote:
> > From: Vabhav Sharma <vabhav.sharma at nxp.com>
> >
> > U-Boot DM model probe only single device at a time which is enabled
> > and configured using device tree or platform data method.
> >
> > PL011 UART IP is SBSA compliant and firmware does the serial port
> > set-up, initialization and let the kernel use UART port for sending
> > and receiving characters.
> >
> > Normally software talk to one serial port time but some LayerScape
> > platform require all the UART devices enabled in Linux for various use
> > case.
> >
> > Adding support to probe all enabled serial devices like SBSA compliant
> > PL011 UART ports probe and initialization by firmware.
> >
> > Signed-off-by: Vabhav Sharma <vabhav.sharma at nxp.com>
> > Reviewed-by: Stefan Roese <sr at denx.de>
> > Reviewed-by: Simon Glass <sjg at chromium.org>
> > --
> > v3:
> >   Incorporated Simon and Stephan review comment
> >   - Define generic function uclass_probe_all(enum uclass_id)
> >     in drivers/core/uclass.c
> >   - Added the function in caller of serial_find_console_or_panic()
> >   - Removed repeated sequence with generic function call uclass_probe_all()
> >   - Dependent on other patch [PATCH] dm: core: add function
> uclass_probe_all()
> >     to probe all devices
> >
> > v2:
> >   Incorporated Stefan review comment, Update #ifdef with macro
> >   if (IS_ENABLED)..
> > ---
> >  drivers/serial/Kconfig         | 17 +++++++++++++++++
> >  drivers/serial/serial-uclass.c |  4 ++++
> >  2 files changed, 21 insertions(+)
> >
> > diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig index
> > b4805a2..af8779b 100644
> > --- a/drivers/serial/Kconfig
> > +++ b/drivers/serial/Kconfig
> > @@ -134,6 +134,23 @@ config SERIAL_SEARCH_ALL
> >
> >  	  If unsure, say N.
> >
> > +config SERIAL_PROBE_ALL
> > +	bool "Probe all available serial devices"
> > +	depends on DM_SERIAL
> > +	default n
> > +	help
> > +	  The serial subsystem only probe for single serial device,
> 
> nit: probes for a
Ok
> 
> > +	  but does not probe for other remaining serial devices.
> > +	  With this option set,we make probing and searching for
> 
> nit: set, we
Sure
>
> > +	  all available devices optional.
> > +	  Normally, U-Boot talk to one serial port at a time but SBSA
> 
> nit: talks
> nit: time, but
Agree
> 
> > +	  compliant UART devices like PL011 require initialization
> > +	  by firmware and let the kernel use serial port for sending
> 
> nit: to let the kernel use the
I understand
> 
> > +	  and receiving the characters.
> > +
> > +	  If probing is not required for all remaining available
> > +	  devices other than default current console device, say N.
> 
> Perhaps use the "If unsure, say N." wording like other Kconfigs.
Got it
> 
> > +
> >  config SPL_DM_SERIAL
> >  	bool "Enable Driver Model for serial drivers in SPL"
> >  	depends on DM_SERIAL && SPL_DM
> > diff --git a/drivers/serial/serial-uclass.c
> > b/drivers/serial/serial-uclass.c index f3c25d4..417d3af 100644
> > --- a/drivers/serial/serial-uclass.c
> > +++ b/drivers/serial/serial-uclass.c
> > @@ -172,6 +172,10 @@ int serial_init(void)
> >  /* Called after relocation */
> >  int serial_initialize(void)
> >  {
> > +	/* Scanning uclass to probe devices */
> > +	if (IS_ENABLED(CONFIG_SERIAL_PROBE_ALL))
> > +		uclass_probe_all(UCLASS_SERIAL);
> > +
> >  	return serial_init();
> >  }
> >
> >