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From: Johan Hovold <johan@kernel.org>
To: Tony Lindgren <tony@atomide.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Rob Herring <robh@kernel.org>,
	Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
	Lee Jones <lee.jones@linaro.org>, Jiri Slaby <jslaby@suse.cz>,
	Johan Hovold <johan@kernel.org>,
	Merlijn Wajer <merlijn@wizzup.org>, Pavel Machek <pavel@ucw.cz>,
	Peter Hurley <peter@hurleysoftware.com>,
	Sebastian Reichel <sre@kernel.org>,
	linux-serial@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org, linux-omap@vger.kernel.org
Subject: Re: [PATCHv6 0/4] n_gsm serdev support and protocol driver for droid4 modem
Date: Thu, 23 Apr 2020 13:43:26 +0200	[thread overview]
Message-ID: <20200423114326.GQ18608@localhost> (raw)
In-Reply-To: <20200421232752.3070-1-tony@atomide.com>

Hi Tony,

On Tue, Apr 21, 2020 at 04:27:48PM -0700, Tony Lindgren wrote:
> Hi all,
> 
> Here's v4 set of n_gsm serdev support patches, and the related protocol
> driver for the modem found on Motorola Mapphone phones and tablets
> like droid4.
> 
> This series only adds basic character device support for the serdev
> driver. Other serdev consumer drivers for specific devices will be
> posted separately.

I'm still missing an architectural (design) overview here -- reviewer
time is a scarce resource.

I also suggested earlier that you include, at least as an RFC, one or
more of your child-device drivers so that we can see how this ends up
being used in the end (including an example devicetree).

Some high-level comments until then:

I'm not sure that a plain chardev interface for the mux channels is the
right interface. The n_gsm ldisc exposes tty devices and I think your
serdev adaptation should continue to do that.

On that note; you're not actually adding general TS 27.010 serdev
support, but rather some hooks and a custom driver and interface (mfd +
/dev/motmdmN) for one particular modem.

I'd rather see a generic implementation which can be used with other
modems and that continues to expose a /dev/gsmttyN interface to which we
could attach serdev clients instead (and not create a motmdm serdev
replica of sorts).

I know the location of this driver has been up for discussion already,
but drivers/tty/serdev/protocol still isn't right (e.g. we don't have an
drivers/i2c/protocol directory where we stuff random i2c client
drivers).

It's an mfd + custom chardev driver for a modem and related to n_gsm
(even more if you add generic serdev support). Currently, drivers/mfd or
drivers/misc appear to be better choices. Otherwise, n_gsm lives in
drivers/tty since it's a line discipline, but it could be moved to a new
drivers/modem if needed (cf. the bluetooth hci ldisc).

Last, it seems you've based the serdev-ngsm-motmdm.c chardev
implementation on a more or less verbatim copy of drivers/gnss/core.c.
I'd appreciate if you could mention that in the file header and
reproduce the copyright notice if you end up keeping that interface.

> Tony Lindgren (4):
>   tty: n_gsm: Add support for serdev drivers
>   serdev: ngsm-motmdm: Add Motorola TS 27.010 serdev modem driver for
>     droid4
>   dt-bindings: serdev: motmdm: Add binding for motorola-mdm
>   ARM: dts: omap4-droid4: Enable basic modem support
> 
>  .../serdev/motorola,mapphone-mdm6600.yaml     |   34 +
>  .../boot/dts/motorola-mapphone-common.dtsi    |    6 +
>  drivers/tty/n_gsm.c                           |  372 +++++
>  drivers/tty/serdev/Kconfig                    |    2 +
>  drivers/tty/serdev/Makefile                   |    2 +
>  drivers/tty/serdev/protocol/Kconfig           |   14 +
>  drivers/tty/serdev/protocol/Makefile          |    3 +
>  .../tty/serdev/protocol/serdev-ngsm-motmdm.c  | 1191 +++++++++++++++++
>  include/linux/serdev-gsm.h                    |  168 +++
>  9 files changed, 1792 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/serdev/motorola,mapphone-mdm6600.yaml
>  create mode 100644 drivers/tty/serdev/protocol/Kconfig
>  create mode 100644 drivers/tty/serdev/protocol/Makefile
>  create mode 100644 drivers/tty/serdev/protocol/serdev-ngsm-motmdm.c
>  create mode 100644 include/linux/serdev-gsm.h

Johan

  parent reply	other threads:[~2020-04-23 11:43 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-21 23:27 Tony Lindgren
2020-04-21 23:27 ` [PATCH 1/4] tty: n_gsm: Add support for serdev drivers Tony Lindgren
2020-04-21 23:27 ` [PATCH 2/4] serdev: ngsm-motmdm: Add Motorola TS 27.010 serdev modem driver for droid4 Tony Lindgren
2020-04-21 23:27 ` [PATCH 3/4] dt-bindings: serdev: motmdm: Add binding for motorola-mdm Tony Lindgren
2020-04-21 23:27 ` [PATCH 4/4] ARM: dts: omap4-droid4: Enable basic modem support Tony Lindgren
2020-04-23 11:43 ` Johan Hovold [this message]
2020-04-23 15:37   ` [PATCHv6 0/4] n_gsm serdev support and protocol driver for droid4 modem Tony Lindgren
2020-04-23 23:27     ` Tony Lindgren
2020-04-25 16:58       ` Tony Lindgren
2020-05-28  8:24     ` Johan Hovold
2020-12-20 22:48       ` Pavel Machek
2020-12-24  8:02         ` Tony Lindgren
2020-12-24 14:59           ` Pavel Machek
2021-01-02 16:23           ` Pavel Machek
2020-04-24 21:50   ` Pavel Machek
2020-04-24 22:15     ` Tony Lindgren
2020-04-26  7:27       ` Pavel Machek
2020-04-26 20:07       ` Pavel Machek
2020-04-26 23:25         ` Tony Lindgren

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