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[104.188.17.28]) by smtp.gmail.com with ESMTPSA id z6sm16696078pfn.212.2020.03.24.13.52.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 24 Mar 2020 13:52:12 -0700 (PDT) Date: Tue, 24 Mar 2020 13:52:10 -0700 From: Bjorn Andersson To: Arnaud Pouliquen Cc: Ohad Ben-Cohen , Greg Kroah-Hartman , Jiri Slaby , linux-kernel@vger.kernel.org, linux-remoteproc@vger.kernel.org, Mathieu Poirier , Suman Anna , Fabien DESSENNE , linux-stm32@st-md-mailman.stormreply.com, Alan Cox , xiang xiao Subject: Re: [PATCH v7 2/2] tty: add rpmsg driver Message-ID: <20200324205210.GE119913@minitux> References: <20200324170407.16470-1-arnaud.pouliquen@st.com> <20200324170407.16470-3-arnaud.pouliquen@st.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200324170407.16470-3-arnaud.pouliquen@st.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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