From: Samuel Thibault <samuel.thibault@gnu.org>
To: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Cc: Gerd Hoffmann <kraxel@redhat.com>, QEMU <qemu-devel@nongnu.org>,
Aurelien Jarno <aurelien@aurel32.net>,
Jason Andryuk <jandryuk@gmail.com>
Subject: Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
Date: Mon, 26 Oct 2020 16:04:32 +0100 [thread overview]
Message-ID: <20201026150432.yqkyceke5uppqom5@function> (raw)
In-Reply-To: <38110b4a-34b1-3e97-5a7f-4fad1bfff080@ilande.co.uk>
Mark Cave-Ayland, le lun. 26 oct. 2020 13:40:05 +0000, a ecrit:
> On 26/10/2020 13:00, Jason Andryuk wrote:
> > On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > > Aurelien, you introduced the "| 1" in
> > >
> > > commit abb8a13918ecc1e8160aa78582de9d5224ea70df
> > > Author: Aurelien Jarno <aurelien@aurel32.net>
> > > Date: Wed Aug 13 04:23:17 2008 +0000
> > >
> > > usb-serial: add support for modem lines
> > >
> > > [...]
> > > @@ -357,9 +393,9 @@ static int usb_serial_handle_control(USBDevice *dev, int request, int value,
> > > /* TODO: TX ON/OFF */
> > > break;
> > > case DeviceInVendor | FTDI_GET_MDM_ST:
> > > - /* TODO: return modem status */
> > > - data[0] = 0;
> > > - ret = 1;
> > > + data[0] = usb_get_modem_lines(s) | 1;
> > > + data[1] = 0;
> > > + ret = 2;
> > > break;
> >
> > I'm not particularly familiar with the FTDI USB serial devices. I
> > found setting FTDI_THRE | FTDI_TEMT by comparing with real hardware.
> >
> > A little searching found this:
> > https://elixir.bootlin.com/linux/latest/source/drivers/usb/serial/ftdi_sio.h#L541
> >
> > That shows "B0 Reserved - must be 1", so maybe that is why "| 1" was added?
>
> Right - that's for the modem status returned as part of the first 2 status
> bytes for incoming data which is slightly different from modem status
> returned directly from FTDI_SIO_GET_MODEM_STATUS: https://elixir.bootlin.com/linux/latest/source/drivers/usb/serial/ftdi_sio.h#L423.
>
> It is the latter which this patch changes and appears to match what I see on
> my Chipi-X hardware here.
Aurelien, do you remember the reason for the addition of 1 here? It does
look like the confusion between the incoming data bytes and the modem
status bytes.
Samuel
next prev parent reply other threads:[~2020-10-26 15:08 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-26 8:33 [PATCH 0/9] dev-serial: minor fixes and improvements Mark Cave-Ayland
2020-10-26 8:33 ` [PATCH 1/9] dev-serial: style changes to improve readability and checkpatch fixes Mark Cave-Ayland
2020-10-26 9:35 ` Samuel Thibault
2020-10-26 8:33 ` [PATCH 2/9] dev-serial: use USB_SERIAL QOM macro for USBSerialState assignments Mark Cave-Ayland
2020-10-26 9:37 ` Samuel Thibault
2020-10-27 9:04 ` Philippe Mathieu-Daudé
2020-10-26 8:33 ` [PATCH 3/9] dev-serial: convert from DPRINTF to trace-events Mark Cave-Ayland
2020-10-26 9:38 ` Samuel Thibault
2020-10-27 9:08 ` Philippe Mathieu-Daudé
2020-10-26 8:33 ` [PATCH 4/9] dev-serial: add trace-events for baud rate and data parameters Mark Cave-Ayland
2020-10-26 9:40 ` Samuel Thibault
2020-10-27 9:08 ` Philippe Mathieu-Daudé
2020-10-26 8:33 ` [PATCH 5/9] dev-serial: replace DeviceOutVendor/DeviceInVendor with equivalent macros from usb.h Mark Cave-Ayland
2020-10-26 9:41 ` Samuel Thibault
2020-10-27 9:09 ` Philippe Mathieu-Daudé
2020-10-26 8:33 ` [PATCH 6/9] dev-serial: add always-plugged property to ensure USB device is always attached Mark Cave-Ayland
2020-10-26 9:45 ` Samuel Thibault
2020-10-27 8:09 ` Gerd Hoffmann
2020-10-27 13:23 ` Mark Cave-Ayland
2020-10-26 8:33 ` [PATCH 7/9] dev-serial: add support for setting data_bits in QEMUSerialSetParams Mark Cave-Ayland
2020-10-26 9:46 ` Samuel Thibault
2020-10-26 8:34 ` [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response Mark Cave-Ayland
2020-10-26 9:54 ` Samuel Thibault
2020-10-26 10:58 ` Mark Cave-Ayland
2020-10-26 11:14 ` Samuel Thibault
2020-10-26 13:00 ` Jason Andryuk
2020-10-26 13:40 ` Mark Cave-Ayland
2020-10-26 14:04 ` Jason Andryuk
2020-10-26 15:04 ` Samuel Thibault [this message]
2020-10-27 13:18 ` Mark Cave-Ayland
2020-10-27 13:30 ` Jason Andryuk
2020-10-26 8:34 ` [PATCH 9/9] dev-serial: store flow control and xon/xoff characters Mark Cave-Ayland
2020-10-26 9:58 ` Samuel Thibault
2020-10-26 9:59 ` [PATCH 0/9] dev-serial: minor fixes and improvements Samuel Thibault
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201026150432.yqkyceke5uppqom5@function \
--to=samuel.thibault@gnu.org \
--cc=aurelien@aurel32.net \
--cc=jandryuk@gmail.com \
--cc=kraxel@redhat.com \
--cc=mark.cave-ayland@ilande.co.uk \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).