Re: [RFC/RFT] PS/2 strict protocol checking and reconnect for KVM users

From: Vojtech Pavlik
Date: Tue Mar 23 2004 - 03:02:08 EST

On Tue, Mar 23, 2004 at 01:57:47AM -0500, Dmitry Torokhov wrote:
> Hi,
>
> I have heard many complaints from KVM users who lose mouse when switching
> to 2.6 when KVM for some reason suppresses the 0xAA 0x00 announce sequence
> from the mouse and mouse is reset to protocol other then kernel expects to
> get.
>
> I am trying to extend psmouse.resetafter option that is right now work only
> for Synaptics touchpads to work with other types of hardware connected to
> PS/2 port. Unfortunately standard PS/2 protocol has pretty much no pattern
> that can be used to reliably validate the data stream. The only requirement
> is that 1st byte has 4th bit set to 1. Unfortunately there are devices that
> violate even this rule, so it can't be turned on by default requiring one
> more option - psmouse.strict.

I have some ideas about a statistical synchronizer for the PS/2, ImPS/2
and ExPS/2 protocol. There is IMO no way to recognize the PS2++ vs PS/2
change.

The X and Y values are usually < 8, the buttons are usually not pressed,
etc. From that and the interbyte timing one should be able to guess
whether he sees a 3-byte per packet or 4-byte per packet protocol after
a few packets, and also where the packets start.

> So, if you are a KVM user and your mouse stops working after switching from
> 2.6 and back please try the patch below and pass psmouse.strict and
> psmouse.resetafter=3 parameters to your kernel and tell me if it works for you
> (unfotrunately I do not have a KVM to play with).
>
> --
> Dmitry
>
>
> ===================================================================
>
>
> ChangeSet@xxxxxx, 2004-03-23 01:51:34-05:00, dtor_core@xxxxxxxxxxxxx
> Input: - Implement strict PS/2 protocol checking - disabled by default,
> activated via psmouse.strict option.
> - Make psmouse.resetafter work for all types of PS/2 devices.
> Together with psmouse.strict should help users of KVM switces
> re-initialize mouse after switching to 2.6 box.
>
>
> Documentation/kernel-parameters.txt | 6 ++-
> drivers/input/mouse/psmouse-base.c | 67 ++++++++++++++++++++++++++----------
> drivers/input/mouse/psmouse.h | 8 +++-
> drivers/input/mouse/synaptics.c | 24 ++++--------
> drivers/input/mouse/synaptics.h | 3 -
> 5 files changed, 70 insertions(+), 38 deletions(-)
>
>
> ===================================================================
>
>
>
> diff -Nru a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> --- a/Documentation/kernel-parameters.txt Tue Mar 23 01:53:31 2004
> +++ b/Documentation/kernel-parameters.txt Tue Mar 23 01:53:31 2004
> @@ -881,13 +881,15 @@
> psmouse.rate= [HW,MOUSE] Set desired mouse report rate, in reports
> per second.
> psmouse.resetafter=
> - [HW,MOUSE] Try to reset Synaptics Touchpad after so many
> - bad packets (0 = never).
> + [HW,MOUSE] Try to reset the device after so many bad packets
> + (0 = never).
> psmouse.resolution=
> [HW,MOUSE] Set desired mouse resolution, in dpi.
> psmouse.smartscroll=
> [HW,MOUSE] Controls Logitech smartscroll autorepeat,
> 0 = disabled, 1 = enabled (default).
> + psmouse.strict= [HW,MOUSE] Enforce strict PS/2 protocol,
> + 0 = disabled (default), 1 = enabled.
>
> pss= [HW,OSS] Personal Sound System (ECHO ESC614)
> Format: <io>,<mss_io>,<mss_irq>,<mss_dma>,<mpu_io>,<mpu_irq>
> diff -Nru a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
> --- a/drivers/input/mouse/psmouse-base.c Tue Mar 23 01:53:31 2004
> +++ b/drivers/input/mouse/psmouse-base.c Tue Mar 23 01:53:31 2004
> @@ -43,9 +43,13 @@
> module_param_named(smartscroll, psmouse_smartscroll, bool, 0);
> MODULE_PARM_DESC(smartscroll, "Logitech Smartscroll autorepeat, 1 = enabled (default), 0 = disabled.");
>
> +static int psmouse_strict;
> +module_param_named(strict, psmouse_strict, bool, 0);
> +MODULE_PARM_DESC(smartscroll, "Enforce strict PS/2 protocol. Useful for KVM switches.");
> +
> unsigned int psmouse_resetafter;
> module_param_named(resetafter, psmouse_resetafter, uint, 0);
> -MODULE_PARM_DESC(resetafter, "Reset Synaptics Touchpad after so many bad packets (0 = never).");
> +MODULE_PARM_DESC(resetafter, "Try resetting the device after so many bad packets (0 = never).");
>
> __obsolete_setup("psmouse_noext");
> __obsolete_setup("psmouse_resolution=");
> @@ -56,15 +60,26 @@
> static char *psmouse_protocols[] = { "None", "PS/2", "PS2++", "PS2T++", "GenPS/2", "ImPS/2", "ImExPS/2", "SynPS/2"};
>
> /*
> - * psmouse_process_packet() analyzes the PS/2 mouse packet contents and
> - * reports relevant events to the input module.
> + * psmouse_process_byte() analyzes the PS/2 data stream and reports reports
> + * relevant events to the input module once full packet has arrived.
> */
>
> -static void psmouse_process_packet(struct psmouse *psmouse, struct pt_regs *regs)
> +static int psmouse_process_byte(struct psmouse *psmouse, struct pt_regs *regs)
> {
> struct input_dev *dev = &psmouse->dev;
> unsigned char *packet = psmouse->packet;
>
> + if (psmouse->pktcnt == 1 && psmouse_strict)
> + if (!(packet[0] & 0x08))
> + return PSMOUSE_BAD_DATA;
> +
> + if (psmouse->pktcnt < 3 + (psmouse->type >= PSMOUSE_GENPS))
> + return PSMOUSE_GOOD_DATA;
> +
> +/*
> + * Full packet accumulated, process it
> + */
> +
> input_regs(dev, regs);
>
> /*
> @@ -112,6 +127,8 @@
> input_report_rel(dev, REL_Y, packet[2] ? (int) ((packet[0] << 3) & 0x100) - (int) packet[2] : 0);
>
> input_sync(dev);
> +
> + return PSMOUSE_FULL_PACKET;
> }
>
> /*
> @@ -123,6 +140,7 @@
> unsigned char data, unsigned int flags, struct pt_regs *regs)
> {
> struct psmouse *psmouse = serio->private;
> + int rc;
>
> if (psmouse->state == PSMOUSE_IGNORE)
> goto out;
> @@ -180,7 +198,7 @@
> if (psmouse->pktcnt == 2) {
> if (psmouse->packet[1] == PSMOUSE_RET_ID) {
> psmouse->state = PSMOUSE_IGNORE;
> - serio_rescan(serio);
> + serio_reconnect(serio);
> goto out;
> }
> if (psmouse->type == PSMOUSE_SYNAPTICS) {
> @@ -193,19 +211,34 @@
> }
> }
>
> - if (psmouse->type == PSMOUSE_SYNAPTICS) {
> - /*
> - * The synaptics driver has its own resync logic,
> - * so it needs to receive all bytes one at a time.
> - */
> - synaptics_process_byte(psmouse, regs);
> - goto out;
> - }
> + rc = psmouse->type == PSMOUSE_SYNAPTICS ?
> + synaptics_process_byte(psmouse, regs) : psmouse_process_byte(psmouse, regs);
>
> - if (psmouse->pktcnt == 3 + (psmouse->type >= PSMOUSE_GENPS)) {
> - psmouse_process_packet(psmouse, regs);
> - psmouse->pktcnt = 0;
> - goto out;
> + switch (rc) {
> + case PSMOUSE_BAD_DATA:
> + printk(KERN_WARNING "psmouse.c: %s at %s lost sync at byte %d\n",
> + psmouse->name, psmouse->phys, psmouse->pktcnt);
> + psmouse->pktcnt = 0;
> +
> + if (++psmouse->out_of_sync == psmouse_resetafter) {
> + psmouse->state = PSMOUSE_IGNORE;
> + printk(KERN_NOTICE "psmouse.c: issuing reconnect request\n");
> + serio_reconnect(psmouse->serio);
> + }
> + break;
> +
> + case PSMOUSE_FULL_PACKET:
> + psmouse->pktcnt = 0;
> + if (psmouse->out_of_sync) {
> + psmouse->out_of_sync = 0;
> + printk(KERN_NOTICE "psmouse.c: %s at %s - driver resynched.\n",
> + psmouse->name, psmouse->phys);
> + }
> + break;
> +
> + case PSMOUSE_GOOD_DATA:
> + default:
> + break;
> }
> out:
> return IRQ_HANDLED;
> diff -Nru a/drivers/input/mouse/psmouse.h b/drivers/input/mouse/psmouse.h
> --- a/drivers/input/mouse/psmouse.h Tue Mar 23 01:53:31 2004
> +++ b/drivers/input/mouse/psmouse.h Tue Mar 23 01:53:31 2004
> @@ -22,6 +22,11 @@
> #define PSMOUSE_ACTIVATED 1
> #define PSMOUSE_IGNORE 2
>
> +/* psmouse protocol handler return codes */
> +#define PSMOUSE_GOOD_DATA 0
> +#define PSMOUSE_BAD_DATA 1
> +#define PSMOUSE_FULL_PACKET 2
> +
> struct psmouse;
>
> struct psmouse_ptport {
> @@ -45,10 +50,11 @@
> unsigned char type;
> unsigned char model;
> unsigned long last;
> + unsigned long out_of_sync;
> unsigned char state;
> char acking;
> volatile char ack;
> - char error;
> + char spare;
> char devname[64];
> char phys[32];
>
> diff -Nru a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
> --- a/drivers/input/mouse/synaptics.c Tue Mar 23 01:53:31 2004
> +++ b/drivers/input/mouse/synaptics.c Tue Mar 23 01:53:31 2004
> @@ -607,6 +607,9 @@
> static unsigned char oldabs_mask[] = { 0xC0, 0x60, 0x00, 0xC0, 0x60 };
> static unsigned char oldabs_rslt[] = { 0xC0, 0x00, 0x00, 0x80, 0x00 };
>
> + if (idx < 0 || idx > 4)
> + return 0;
> +
> switch (pkt_type) {
> case SYN_NEWABS:
> case SYN_NEWABS_RELAXED:
> @@ -637,7 +640,7 @@
> return SYN_NEWABS_STRICT;
> }
>
> -void synaptics_process_byte(struct psmouse *psmouse, struct pt_regs *regs)
> +int synaptics_process_byte(struct psmouse *psmouse, struct pt_regs *regs)
> {
> struct input_dev *dev = &psmouse->dev;
> struct synaptics_data *priv = psmouse->private;
> @@ -645,11 +648,6 @@
> input_regs(dev, regs);
>
> if (psmouse->pktcnt >= 6) { /* Full packet received */
> - if (priv->out_of_sync) {
> - priv->out_of_sync = 0;
> - printk(KERN_NOTICE "Synaptics driver resynced.\n");
> - }
> -
> if (unlikely(priv->pkt_type == SYN_NEWABS))
> priv->pkt_type = synaptics_detect_pkt_type(psmouse);
>
> @@ -657,16 +655,10 @@
> synaptics_pass_pt_packet(&psmouse->ptport->serio, psmouse->packet);
> else
> synaptics_process_packet(psmouse);
> - psmouse->pktcnt = 0;
>
> - } else if (psmouse->pktcnt &&
> - !synaptics_validate_byte(psmouse->packet, psmouse->pktcnt - 1, priv->pkt_type)) {
> - printk(KERN_WARNING "Synaptics driver lost sync at byte %d\n", psmouse->pktcnt);
> - psmouse->pktcnt = 0;
> - if (++priv->out_of_sync == psmouse_resetafter) {
> - psmouse->state = PSMOUSE_IGNORE;
> - printk(KERN_NOTICE "synaptics: issuing reconnect request\n");
> - serio_reconnect(psmouse->serio);
> - }
> + return PSMOUSE_FULL_PACKET;
> }
> +
> + return synaptics_validate_byte(psmouse->packet, psmouse->pktcnt - 1, priv->pkt_type) ?
> + PSMOUSE_GOOD_DATA : PSMOUSE_BAD_DATA;
> }
> diff -Nru a/drivers/input/mouse/synaptics.h b/drivers/input/mouse/synaptics.h
> --- a/drivers/input/mouse/synaptics.h Tue Mar 23 01:53:31 2004
> +++ b/drivers/input/mouse/synaptics.h Tue Mar 23 01:53:31 2004
> @@ -9,7 +9,7 @@
> #ifndef _SYNAPTICS_H
> #define _SYNAPTICS_H
>
> -extern void synaptics_process_byte(struct psmouse *psmouse, struct pt_regs *regs);
> +extern int synaptics_process_byte(struct psmouse *psmouse, struct pt_regs *regs);
> extern int synaptics_detect(struct psmouse *psmouse);
> extern int synaptics_init(struct psmouse *psmouse);
> extern void synaptics_reset(struct psmouse *psmouse);
> @@ -108,7 +108,6 @@
> unsigned long int identity; /* Identification */
>
> /* Data for normal processing */
> - unsigned int out_of_sync; /* # of packets out of sync */
> int old_w; /* Previous w value */
> unsigned char pkt_type; /* packet type - old, new, etc */
> };
>

--
Vojtech Pavlik
SuSE Labs, SuSE CR
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/