From: Greg KH <gregkh@linuxfoundation.org>
To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: sean.wang@mediatek.com, robh+dt@kernel.org, jslaby@suse.com,
robert.jarzmik@free.fr, arnd@arndb.de, p.zabel@pengutronix.de,
joel@jms.id.au, david@lechnology.com, jan.kiszka@siemens.com,
heikki.krogerus@linux.intel.com, hpeter@gmail.com,
vigneshr@ti.com, matthias.bgg@gmail.com,
tthayer@opensource.altera.com, devicetree@vger.kernel.org,
linux-mediatek@lists.infradead.org, linux-serial@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org,
Steven Liu <steven.liu@mediatek.com>,
Ryder Lee <ryder.lee@mediatek.com>
Subject: Re: [PATCH v4] tty: serial: don't do termios for BTIF
Date: Mon, 29 Jun 2020 10:40:51 +0200 [thread overview]
Message-ID: <20200629084051.GA1234189@kroah.com> (raw)
In-Reply-To: <20200629082927.GA3703480@smile.fi.intel.com>
On Mon, Jun 29, 2020 at 11:29:27AM +0300, Andy Shevchenko wrote:
> On Sat, Jun 27, 2020 at 04:12:22PM +0200, Greg KH wrote:
> > On Sat, Jun 20, 2020 at 03:59:14AM +0800, sean.wang@mediatek.com wrote:
> > > From: Sean Wang <sean.wang@mediatek.com>
> > >
> > > Bluetooth Interface (BTIF) is designed dedicatedly for MediaTek SOC with
> > > BT in order to be instead of the UART interface between BT module and Host
> > > CPU, and not exported to user space to access.
> > >
> > > As the UART design, BTIF will be an APB slave and can transmit or receive
> > > data by MCU access, but doesn't provide termios function like baudrate and
> > > flow control setup.
> > >
> > > Even LCR on offset 0xC that is just a FAKELCR
> > > a. If FAKELCR[7] is equaled to 1, RBR(0x00), THR(0x00), IER(0x04)
> > > will not be readable/writable.
> > >
> > > b. If FAKELCR is equaled to 0xBF, RBR(0x00), THR(0x00), IER(0x04),
> > > IIR(0x08), and LSR(0x14) will not be readable/writable.
> > >
> > > So adding a new capability 'UART_CAP_NTIO' for the unusual unsupported
> > > case.
> > >
> > > The bluetooth driver would use BTIF device as a serdev. So the termios
> > > still function would be called in kernelspace from ttyport_open in
> > > drivers/tty/serdev/serdev-ttyprt.c.
>
> > > +#define UART_CAP_NTIO (1 << 18) /* UART doesn't do termios */
> >
> > Naming is hard. I will never remember what "NTIO" is, how about we make
> > it explicit:
> > define UART_CAP_IGNORE_TERMIOS
> >
> > And the _CAP_ name is getting out of hand, this isn't a "capability",
> > it's a "quirk for this port" but that's a battle to worry about later...
>
> For quirks we have a separate field in struct uart_port. Perhaps that can be used?
That would be much nicer, if possible.
thanks,
greg k-h
prev parent reply other threads:[~2020-06-29 21:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-19 19:59 [PATCH v4] tty: serial: don't do termios for BTIF sean.wang
2020-06-27 14:12 ` Greg KH
2020-06-29 8:29 ` Andy Shevchenko
2020-06-29 8:40 ` Greg KH [this message]
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