From: Bjorn Andersson <bjorn.andersson@linaro.org> To: Arnaud Pouliquen <arnaud.pouliquen@st.com> Cc: Ohad Ben-Cohen <ohad@wizery.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.com>, linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, Mathieu Poirier <mathieu.poirier@linaro.org>, Suman Anna <s-anna@ti.com>, Fabien DESSENNE <fabien.dessenne@st.com>, linux-stm32@st-md-mailman.stormreply.com, Alan Cox <gnomes@lxorguk.ukuu.org.uk>, xiang xiao <xiaoxiang781216@gmail.com> Subject: Re: [PATCH v7 2/2] tty: add rpmsg driver Date: Tue, 24 Mar 2020 13:52:13 -0700 [thread overview] Message-ID: <20200324205210.GE119913@minitux> (raw) In-Reply-To: <20200324170407.16470-3-arnaud.pouliquen@st.com> On Tue 24 Mar 10:04 PDT 2020, Arnaud Pouliquen wrote: [..] > diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile > index 020b1cd9294f..c2465e7ebc2a 100644 > --- a/drivers/tty/Makefile > +++ b/drivers/tty/Makefile > @@ -34,5 +34,6 @@ obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o > obj-$(CONFIG_GOLDFISH_TTY) += goldfish.o > obj-$(CONFIG_MIPS_EJTAG_FDC_TTY) += mips_ejtag_fdc.o > obj-$(CONFIG_VCC) += vcc.o > +obj-$(CONFIG_RPMSG_TTY) += rpmsg_tty.o > > obj-y += ipwireless/ > diff --git a/drivers/tty/rpmsg_tty.c b/drivers/tty/rpmsg_tty.c [..] > +static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = { > + { .name = TTY_CH_NAME_RAW }, > + { .name = TTY_CH_NAME_WITH_CTS}, I still don't like the idea that the tty devices are tied to channels by fixed names. This makes the driver unusable for communicating with any firmware out there that provides tty-like data over a channel with a different name - such as modems with channels providing an AT command interface (they are not named "rpmsg-tty-raw"). I also fail to see how you would distinguish ttys when the firmware provides more than a single tty - e.g. say you have a modem-like device that provides an AT command channel and a NMEA stream. These are the reasons why drivers/rpmsg/rpmsg_char registers a "control device", from which you can spawn new char devices. As I've said before, I really think the same approach should be taken for ttys - perhaps by just extending the rpmsg_char to allow it to create tty devices in addition to the "packet based" char device? Regards, Bjorn
WARNING: multiple messages have this Message-ID (diff)
From: Bjorn Andersson <bjorn.andersson@linaro.org> To: Arnaud Pouliquen <arnaud.pouliquen@st.com> Cc: Ohad Ben-Cohen <ohad@wizery.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.com>, linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, Mathieu Poirier <mathieu.poirier@linaro.org>, Suman Anna <s-anna@ti.com>, Fabien DESSENNE <fabien.dessenne@st.com>, linux-stm32@st-md-mailman.stormreply.com, Alan Cox <gnomes@lxorguk.ukuu.org.uk>, xiang xiao <xiaoxiang781216@gmail.com> Subject: Re: [PATCH v7 2/2] tty: add rpmsg driver Date: Tue, 24 Mar 2020 13:52:10 -0700 [thread overview] Message-ID: <20200324205210.GE119913@minitux> (raw) In-Reply-To: <20200324170407.16470-3-arnaud.pouliquen@st.com> On Tue 24 Mar 10:04 PDT 2020, Arnaud Pouliquen wrote: [..] > diff --git a/drivers/tty/Makefile b/drivers/tty/Makefile > index 020b1cd9294f..c2465e7ebc2a 100644 > --- a/drivers/tty/Makefile > +++ b/drivers/tty/Makefile > @@ -34,5 +34,6 @@ obj-$(CONFIG_PPC_EPAPR_HV_BYTECHAN) += ehv_bytechan.o > obj-$(CONFIG_GOLDFISH_TTY) += goldfish.o > obj-$(CONFIG_MIPS_EJTAG_FDC_TTY) += mips_ejtag_fdc.o > obj-$(CONFIG_VCC) += vcc.o > +obj-$(CONFIG_RPMSG_TTY) += rpmsg_tty.o > > obj-y += ipwireless/ > diff --git a/drivers/tty/rpmsg_tty.c b/drivers/tty/rpmsg_tty.c [..] > +static struct rpmsg_device_id rpmsg_driver_tty_id_table[] = { > + { .name = TTY_CH_NAME_RAW }, > + { .name = TTY_CH_NAME_WITH_CTS}, I still don't like the idea that the tty devices are tied to channels by fixed names. This makes the driver unusable for communicating with any firmware out there that provides tty-like data over a channel with a different name - such as modems with channels providing an AT command interface (they are not named "rpmsg-tty-raw"). I also fail to see how you would distinguish ttys when the firmware provides more than a single tty - e.g. say you have a modem-like device that provides an AT command channel and a NMEA stream. These are the reasons why drivers/rpmsg/rpmsg_char registers a "control device", from which you can spawn new char devices. As I've said before, I really think the same approach should be taken for ttys - perhaps by just extending the rpmsg_char to allow it to create tty devices in addition to the "packet based" char device? Regards, Bjorn
next prev parent reply other threads:[~2020-03-24 20:52 UTC|newest] Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-03-24 17:04 [PATCH v7 0/2] Add rpmsg tty driver Arnaud Pouliquen 2020-03-24 17:04 ` Arnaud Pouliquen 2020-03-24 17:04 ` [PATCH v7 1/2] rpmsg: core: add API to get MTU Arnaud Pouliquen 2020-03-24 17:04 ` Arnaud Pouliquen 2020-03-31 17:36 ` Mathieu Poirier 2020-04-01 6:28 ` Jiri Slaby 2020-04-01 6:29 ` Jiri Slaby 2020-04-01 11:34 ` Arnaud POULIQUEN 2020-04-01 11:34 ` Arnaud POULIQUEN 2020-03-24 17:04 ` [PATCH v7 2/2] tty: add rpmsg driver Arnaud Pouliquen 2020-03-24 17:04 ` Arnaud Pouliquen 2020-03-24 17:18 ` Greg Kroah-Hartman 2020-03-25 11:34 ` Arnaud POULIQUEN 2020-03-25 11:34 ` Arnaud POULIQUEN 2020-03-24 17:23 ` Joe Perches 2020-03-25 11:36 ` Arnaud POULIQUEN 2020-03-25 11:36 ` Arnaud POULIQUEN 2020-03-24 17:44 ` Randy Dunlap 2020-03-25 8:10 ` Jiri Slaby 2020-03-25 11:39 ` Arnaud POULIQUEN 2020-03-25 11:39 ` Arnaud POULIQUEN 2020-03-24 20:52 ` Bjorn Andersson [this message] 2020-03-24 20:52 ` Bjorn Andersson 2020-03-25 16:57 ` Arnaud POULIQUEN 2020-03-25 16:57 ` Arnaud POULIQUEN 2020-04-06 14:18 ` Arnaud POULIQUEN 2020-04-06 14:18 ` Arnaud POULIQUEN 2020-05-06 2:54 ` Bjorn Andersson 2020-05-06 10:21 ` Arnaud POULIQUEN 2020-03-25 8:45 ` Jiri Slaby 2020-03-25 13:15 ` Arnaud POULIQUEN 2020-03-25 13:15 ` Arnaud POULIQUEN 2020-03-25 13:31 ` Jiri Slaby 2020-03-26 0:01 ` Joe Perches 2020-03-26 6:38 ` Jiri Slaby 2020-03-26 10:59 ` Arnaud POULIQUEN 2020-03-26 10:59 ` Arnaud POULIQUEN 2020-03-26 12:31 ` Jiri Slaby 2020-03-26 11:40 ` Arnaud POULIQUEN 2020-03-26 11:40 ` Arnaud POULIQUEN 2020-03-26 11:45 ` Jiri Slaby 2020-04-01 18:06 ` Mathieu Poirier 2020-04-02 15:25 ` Arnaud POULIQUEN 2020-04-02 15:25 ` Arnaud POULIQUEN 2020-04-03 20:18 ` Mathieu Poirier 2020-07-15 16:06 ` [PATCH v7 0/2] Add rpmsg tty driver Arnaud POULIQUEN
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