Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
On 26/10/2020 15:04, Samuel Thibault wrote: Mark Cave-Ayland, le lun. 26 oct. 2020 13:40:05 +, a ecrit: On 26/10/2020 13:00, Jason Andryuk wrote: On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault wrote: Aurelien, you introduced the "| 1" in commit abb8a13918ecc1e8160aa78582de9d5224ea70df Author: Aurelien Jarno Date: Wed Aug 13 04:23:17 2008 + 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. I spent a bit of time this morning doing some further tests on Linux using 2 machines and a test program to check CTS and usbmon: usbmon when adapter unplugged: 95a4bf2dd300 2366831506 S Ci:4:004:0 s c0 05 0002 2 < 95a4bf2dd300 2366831607 C Ci:4:004:0 0 2 = 0160 usbmon when adapter plugged in and remote connected to minicom: 95a4452a79c0 2457273895 S Ci:4:004:0 s c0 05 0002 2 < 95a4452a79c0 2457274057 C Ci:4:004:0 0 2 = 3160 It seems I made a mistake here since the response is interpreted as 2 bytes rather than a single little-endian word: with CTS asserted on the remote the first byte is 0x31 == FTDI_CTS | FTDI_DSR | 1, whilst the 2nd byte is 0x60 == FTDI_THRE | FTDI_TEMT which matches the existing QEMU code rather than the comments in ftdi_sio.h. So sorry for the noise: I'll drop this patch from the series and post a v2 shortly. ATB, Mark.
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
On Tue, Oct 27, 2020 at 9:18 AM Mark Cave-Ayland wrote: > > I spent a bit of time this morning doing some further tests on Linux using 2 > machines > and a test program to check CTS and usbmon: > > usbmon when adapter unplugged: > 95a4bf2dd300 2366831506 S Ci:4:004:0 s c0 05 0002 2 < > 95a4bf2dd300 2366831607 C Ci:4:004:0 0 2 = 0160 > > usbmon when adapter plugged in and remote connected to minicom: > 95a4452a79c0 2457273895 S Ci:4:004:0 s c0 05 0002 2 < > 95a4452a79c0 2457274057 C Ci:4:004:0 0 2 = 3160 > > It seems I made a mistake here since the response is interpreted as 2 bytes > rather > than a single little-endian word: with CTS asserted on the remote the first > byte is > 0x31 == FTDI_CTS | FTDI_DSR | 1, whilst the 2nd byte is 0x60 == FTDI_THRE | > FTDI_TEMT > which matches the existing QEMU code rather than the comments in ftdi_sio.h. > > So sorry for the noise: I'll drop this patch from the series and post a v2 > shortly. No worries. Thanks for investigating. (I had the thought that maybe reserve bit 0 differentiates one and two byte responses? Bit 0 clear indicates a 1-byte response and set indicates a 2 bit response. But I'm just guessing.) Regards, Jason
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
Mark Cave-Ayland, le lun. 26 oct. 2020 13:40:05 +, a ecrit: > On 26/10/2020 13:00, Jason Andryuk wrote: > > On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault > > wrote: > > > Aurelien, you introduced the "| 1" in > > > > > > commit abb8a13918ecc1e8160aa78582de9d5224ea70df > > > Author: Aurelien Jarno > > > Date: Wed Aug 13 04:23:17 2008 + > > > > > > 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
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
On Mon, Oct 26, 2020 at 9:40 AM Mark Cave-Ayland wrote: > > On 26/10/2020 13:00, Jason Andryuk wrote: > > > On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault > > wrote: > >> > >> Mark Cave-Ayland, le lun. 26 oct. 2020 10:58:43 +, a ecrit: > >>> On 26/10/2020 09:54, Samuel Thibault wrote: > Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +, a ecrit: > > The FTDI_GET_MDM_ST response should only return a single byte > > indicating the > > modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h > > header > > file). > > > > Signed-off-by: Mark Cave-Ayland > > --- > >hw/usb/dev-serial.c | 5 ++--- > >1 file changed, 2 insertions(+), 3 deletions(-) > > > > diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c > > index 4c374d0790..fa734bcf54 100644 > > --- a/hw/usb/dev-serial.c > > +++ b/hw/usb/dev-serial.c > > @@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice > > *dev, USBPacket *p, > >/* TODO: TX ON/OFF */ > >break; > >case VendorDeviceRequest | FTDI_GET_MDM_ST: > > -data[0] = usb_get_modem_lines(s) | 1; > > -data[1] = FTDI_THRE | FTDI_TEMT; > > -p->actual_length = 2; > > +data[0] = usb_get_modem_lines(s); > > +p->actual_length = 1; > > >> [...] > >>> A quick test shows my Chipi-X returns 0x1 0x60 with nothing attached in > >>> response to FTDI_SIO_GET_MODEM_STATUS_REQUEST: assuming the reply length > >>> should be 2 bytes, the comment about B0-B3 being zero and the response > >>> from > >>> my Chip-X above suggests that the "| 1" should still be dropped from the > >>> response. > >> > >> Aurelien, you introduced the "| 1" in > >> > >> commit abb8a13918ecc1e8160aa78582de9d5224ea70df > >> Author: Aurelien Jarno > >> Date: Wed Aug 13 04:23:17 2008 + > >> > >> 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; > >> > >> do you know exactly what it is for? > > > > Hi, > > > > 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. Okay, sorry for the confusion there. I thought your "it's the SIO chipsets that return 1 byte which are older than the chipset being emulated by QEMU" meant you thought your change to 1 byte was unnecessary. You also posted two bytes (0x1 0x60) from your hardware. > It is the latter which this patch changes and appears to match what I see on > my > Chipi-X hardware here. I don't have my hardware readily available, but I must have been seeing 2 bytes from FTDI_GET_MDM_ST with data[1] = FTDI_THRE | FTDI_TEMT; to make the change. I don't have the USB captures anymore to compare the lowest bit value. So right now you are just interested in dropping the lowest bit setting but preserving the 2 bytes modem status? Regards, Jason
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
On 26/10/2020 13:00, Jason Andryuk wrote: On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault wrote: Mark Cave-Ayland, le lun. 26 oct. 2020 10:58:43 +, a ecrit: On 26/10/2020 09:54, Samuel Thibault wrote: Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +, a ecrit: The FTDI_GET_MDM_ST response should only return a single byte indicating the modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h header file). Signed-off-by: Mark Cave-Ayland --- hw/usb/dev-serial.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c index 4c374d0790..fa734bcf54 100644 --- a/hw/usb/dev-serial.c +++ b/hw/usb/dev-serial.c @@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice *dev, USBPacket *p, /* TODO: TX ON/OFF */ break; case VendorDeviceRequest | FTDI_GET_MDM_ST: -data[0] = usb_get_modem_lines(s) | 1; -data[1] = FTDI_THRE | FTDI_TEMT; -p->actual_length = 2; +data[0] = usb_get_modem_lines(s); +p->actual_length = 1; [...] A quick test shows my Chipi-X returns 0x1 0x60 with nothing attached in response to FTDI_SIO_GET_MODEM_STATUS_REQUEST: assuming the reply length should be 2 bytes, the comment about B0-B3 being zero and the response from my Chip-X above suggests that the "| 1" should still be dropped from the response. Aurelien, you introduced the "| 1" in commit abb8a13918ecc1e8160aa78582de9d5224ea70df Author: Aurelien Jarno Date: Wed Aug 13 04:23:17 2008 + 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; do you know exactly what it is for? Hi, 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. ATB, Mark.
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
On Mon, Oct 26, 2020 at 7:21 AM Samuel Thibault wrote: > > Mark Cave-Ayland, le lun. 26 oct. 2020 10:58:43 +, a ecrit: > > On 26/10/2020 09:54, Samuel Thibault wrote: > > > Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +, a ecrit: > > > > The FTDI_GET_MDM_ST response should only return a single byte > > > > indicating the > > > > modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h > > > > header > > > > file). > > > > > > > > Signed-off-by: Mark Cave-Ayland > > > > --- > > > > hw/usb/dev-serial.c | 5 ++--- > > > > 1 file changed, 2 insertions(+), 3 deletions(-) > > > > > > > > diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c > > > > index 4c374d0790..fa734bcf54 100644 > > > > --- a/hw/usb/dev-serial.c > > > > +++ b/hw/usb/dev-serial.c > > > > @@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice > > > > *dev, USBPacket *p, > > > > /* TODO: TX ON/OFF */ > > > > break; > > > > case VendorDeviceRequest | FTDI_GET_MDM_ST: > > > > -data[0] = usb_get_modem_lines(s) | 1; > > > > -data[1] = FTDI_THRE | FTDI_TEMT; > > > > -p->actual_length = 2; > > > > +data[0] = usb_get_modem_lines(s); > > > > +p->actual_length = 1; > > > > [...] > > A quick test shows my Chipi-X returns 0x1 0x60 with nothing attached in > > response to FTDI_SIO_GET_MODEM_STATUS_REQUEST: assuming the reply length > > should be 2 bytes, the comment about B0-B3 being zero and the response from > > my Chip-X above suggests that the "| 1" should still be dropped from the > > response. > > Aurelien, you introduced the "| 1" in > > commit abb8a13918ecc1e8160aa78582de9d5224ea70df > Author: Aurelien Jarno > Date: Wed Aug 13 04:23:17 2008 + > > 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; > > do you know exactly what it is for? Hi, 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? Regards, Jason
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
Mark Cave-Ayland, le lun. 26 oct. 2020 10:58:43 +, a ecrit: > On 26/10/2020 09:54, Samuel Thibault wrote: > > Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +, a ecrit: > > > The FTDI_GET_MDM_ST response should only return a single byte indicating > > > the > > > modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h > > > header > > > file). > > > > > > Signed-off-by: Mark Cave-Ayland > > > --- > > > hw/usb/dev-serial.c | 5 ++--- > > > 1 file changed, 2 insertions(+), 3 deletions(-) > > > > > > diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c > > > index 4c374d0790..fa734bcf54 100644 > > > --- a/hw/usb/dev-serial.c > > > +++ b/hw/usb/dev-serial.c > > > @@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice *dev, > > > USBPacket *p, > > > /* TODO: TX ON/OFF */ > > > break; > > > case VendorDeviceRequest | FTDI_GET_MDM_ST: > > > -data[0] = usb_get_modem_lines(s) | 1; > > > -data[1] = FTDI_THRE | FTDI_TEMT; > > > -p->actual_length = 2; > > > +data[0] = usb_get_modem_lines(s); > > > +p->actual_length = 1; > > [...] > A quick test shows my Chipi-X returns 0x1 0x60 with nothing attached in > response to FTDI_SIO_GET_MODEM_STATUS_REQUEST: assuming the reply length > should be 2 bytes, the comment about B0-B3 being zero and the response from > my Chip-X above suggests that the "| 1" should still be dropped from the > response. Aurelien, you introduced the "| 1" in commit abb8a13918ecc1e8160aa78582de9d5224ea70df Author: Aurelien Jarno Date: Wed Aug 13 04:23:17 2008 + 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; do you know exactly what it is for? Samuel
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
On 26/10/2020 09:54, Samuel Thibault wrote:
Hello,
(Cc-ing Aurelien who introduced the support for modem control, and Jason
who added the missing THRE and TEMT flags).
Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +, a ecrit:
The FTDI_GET_MDM_ST response should only return a single byte indicating the
modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h header
file).
Signed-off-by: Mark Cave-Ayland
---
hw/usb/dev-serial.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
index 4c374d0790..fa734bcf54 100644
--- a/hw/usb/dev-serial.c
+++ b/hw/usb/dev-serial.c
@@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice *dev,
USBPacket *p,
/* TODO: TX ON/OFF */
break;
case VendorDeviceRequest | FTDI_GET_MDM_ST:
-data[0] = usb_get_modem_lines(s) | 1;
-data[1] = FTDI_THRE | FTDI_TEMT;
-p->actual_length = 2;
+data[0] = usb_get_modem_lines(s);
+p->actual_length = 1;
Err, but Linux' drivers/usb/serial/ftdi_sio.c:ftdi_process_packet()
contradicts this:
if (len < 2) {
dev_dbg(&port->dev, "malformed packet\n");
return 0;
}
status = buf[0] & FTDI_STATUS_B0_MASK;
if (status != priv->prev_status) {
char diff_status = status ^ priv->prev_status;
if (diff_status & FTDI_RS0_CTS)
port->icount.cts++;
[...]
/* save if the transmitter is empty or not */
if (buf[1] & FTDI_RS_TEMT)
priv->transmit_empty = 1;
else
priv->transmit_empty = 0;
Did you actually get an issue with seeing this packet contain two bytes?
Hi Samuel,
Thanks for the review! There are 2 different places where the status is read: the one
above in ftdi_process_packet() relates to the control packet header for incoming data
which is always 2 bytes, whereas this relates to FTDI_SIO_GET_MODEM_STATUS_REQUEST in
https://elixir.bootlin.com/linux/latest/source/drivers/usb/serial/ftdi_sio.c#L2825.
I have a FTDI Chipi-X adapter to compare with and that returns 2 bytes, but it looks
like I mis-read the code and it's the SIO chipsets that return 1 byte which are older
than the chipset being emulated by QEMU. This came from reading
https://elixir.bootlin.com/linux/latest/source/drivers/usb/serial/ftdi_sio.h#L415
which states that only 1 byte should be returned, but of course that comment could be
out of date.
A quick test shows my Chipi-X returns 0x1 0x60 with nothing attached in response to
FTDI_SIO_GET_MODEM_STATUS_REQUEST: assuming the reply length should be 2 bytes, the
comment about B0-B3 being zero and the response from my Chip-X above suggests that
the "| 1" should still be dropped from the response.
ATB,
Mark.
Re: [PATCH 8/9] dev-serial: fix FTDI_GET_MDM_ST response
Hello,
(Cc-ing Aurelien who introduced the support for modem control, and Jason
who added the missing THRE and TEMT flags).
Mark Cave-Ayland, le lun. 26 oct. 2020 08:34:00 +, a ecrit:
> The FTDI_GET_MDM_ST response should only return a single byte indicating the
> modem status with bit 0 cleared (as documented in the Linux ftdi_sio.h header
> file).
>
> Signed-off-by: Mark Cave-Ayland
> ---
> hw/usb/dev-serial.c | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/hw/usb/dev-serial.c b/hw/usb/dev-serial.c
> index 4c374d0790..fa734bcf54 100644
> --- a/hw/usb/dev-serial.c
> +++ b/hw/usb/dev-serial.c
> @@ -360,9 +360,8 @@ static void usb_serial_handle_control(USBDevice *dev,
> USBPacket *p,
> /* TODO: TX ON/OFF */
> break;
> case VendorDeviceRequest | FTDI_GET_MDM_ST:
> -data[0] = usb_get_modem_lines(s) | 1;
> -data[1] = FTDI_THRE | FTDI_TEMT;
> -p->actual_length = 2;
> +data[0] = usb_get_modem_lines(s);
> +p->actual_length = 1;
Err, but Linux' drivers/usb/serial/ftdi_sio.c:ftdi_process_packet()
contradicts this:
if (len < 2) {
dev_dbg(&port->dev, "malformed packet\n");
return 0;
}
status = buf[0] & FTDI_STATUS_B0_MASK;
if (status != priv->prev_status) {
char diff_status = status ^ priv->prev_status;
if (diff_status & FTDI_RS0_CTS)
port->icount.cts++;
[...]
/* save if the transmitter is empty or not */
if (buf[1] & FTDI_RS_TEMT)
priv->transmit_empty = 1;
else
priv->transmit_empty = 0;
Did you actually get an issue with seeing this packet contain two bytes?
Samuel
