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Subject[PATCH] Input: synaptics - add retry mechanism for reconnect
Date
On the Samsung Series 5 Chromebook, the Synaptics ClickPad will sometimes not
send an "0xFA" PS/2 ACK in response to a command byte during the reconnect
sequence following a resume from suspend. From our experiments, the failure can
happen during any byte of any of the commands in the reconnect batch.

This failure results in a timeout in the psmouse driver. In addition, the
ClickPad will often also respond to the next PS/2 command byte with an "0xFE"
PS/2 RESEND response.

This patch makes the synaptics reconnect-at-resume more tolerant to such
failures.

Signed-off-by: Chung-yih Wang <cywang@chromium.org>
---
drivers/input/mouse/synaptics.c | 79 ++++++++++++++++++++++++++-------------
1 files changed, 53 insertions(+), 26 deletions(-)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 2f78538..2ee19a5 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -72,33 +72,65 @@
****************************************************************************/

/*
+ * Send a "synaptics" command to the device and retry on PS/2 communication
+ * error
+ */
+static int synaptics_send_cmd_retry(struct psmouse *psmouse, unsigned char cmd,
+ unsigned char *param, int param_c)
+{
+ int tries = 2;
+ do {
+ if (!psmouse_sliced_command(psmouse, cmd) &&
+ !ps2_command(&psmouse->ps2dev, param, param_c)) {
+ return 0;
+ }
+ /*
+ * If the touchpad did not ACK a previous command byte,
+ * it may also respond to the next command byte with 'FE'.
+ * Send a dummy command to clear this possible 'FE'.
+ */
+ ps2_command(&psmouse->ps2dev, NULL, PSMOUSE_CMD_SETSCALE11);
+ } while (--tries > 0);
+ psmouse_err(psmouse, "synaptics_retry failed cmd:0x%02x param_c 0x%x",
+ cmd, param_c);
+ return -1;
+}
+
+/*
* Set the synaptics touchpad mode byte by special commands
*/
static int synaptics_mode_cmd(struct psmouse *psmouse, unsigned char mode)
{
unsigned char param[1];

- if (psmouse_sliced_command(psmouse, mode))
- return -1;
param[0] = SYN_PS_SET_MODE2;
- if (ps2_command(&psmouse->ps2dev, param, PSMOUSE_CMD_SETRATE))
- return -1;
- return 0;
+ return synaptics_send_cmd_retry(psmouse, mode,
+ param, PSMOUSE_CMD_SETRATE);
}

int synaptics_detect(struct psmouse *psmouse, bool set_properties)
{
struct ps2dev *ps2dev = &psmouse->ps2dev;
unsigned char param[4];
+ int tries = 2;

- param[0] = 0;
+ do {
+ param[0] = 0;
+ if (!ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES) &&
+ !ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES) &&
+ !ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES) &&
+ !ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES) &&
+ !ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO)) {
+ goto ps2_command_success;
+ }
+ /* dummy command to reset the communication channel */
+ ps2_command(ps2dev, NULL, PSMOUSE_CMD_SETSCALE11);
+ } while (--tries > 0);

- ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
- ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
- ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
- ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
- ps2_command(ps2dev, param, PSMOUSE_CMD_GETINFO);
+ psmouse_err(psmouse, "synaptics_retry failed in detect()");
+ return -1;

+ps2_command_success:
if (param[1] != 0x47)
return -ENODEV;

@@ -137,11 +169,7 @@ static int synaptics_invert_y(int y)
*/
static int synaptics_send_cmd(struct psmouse *psmouse, unsigned char c, unsigned char *param)
{
- if (psmouse_sliced_command(psmouse, c))
- return -1;
- if (ps2_command(&psmouse->ps2dev, param, PSMOUSE_CMD_GETINFO))
- return -1;
- return 0;
+ return synaptics_send_cmd_retry(psmouse, c, param, PSMOUSE_CMD_GETINFO);
}

/*
@@ -332,11 +360,10 @@ static int synaptics_set_advanced_gesture_mode(struct psmouse *psmouse)
SYN_CAP_IMAGE_SENSOR(priv->ext_cap_0c)))
return 0;

- if (psmouse_sliced_command(psmouse, SYN_QUE_MODEL))
- return -1;
-
- if (ps2_command(&psmouse->ps2dev, &param, PSMOUSE_CMD_SETRATE))
+ if (synaptics_send_cmd_retry(psmouse, SYN_QUE_MODEL,
+ &param, PSMOUSE_CMD_SETRATE)) {
return -1;
+ }

/* Advanced gesture mode also sends multi finger data */
priv->capabilities |= BIT(1);
@@ -393,11 +420,8 @@ static int synaptics_pt_write(struct serio *serio, unsigned char c)
struct psmouse *parent = serio_get_drvdata(serio->parent);
char rate_param = SYN_PS_CLIENT_CMD; /* indicates that we want pass-through port */

- if (psmouse_sliced_command(parent, c))
- return -1;
- if (ps2_command(&parent->ps2dev, &rate_param, PSMOUSE_CMD_SETRATE))
- return -1;
- return 0;
+ return synaptics_send_cmd_retry(parent, c,
+ &rate_param, PSMOUSE_CMD_SETRATE);
}

static int synaptics_pt_start(struct serio *serio)
@@ -1383,7 +1407,10 @@ static int synaptics_reconnect(struct psmouse *psmouse)
int error;

do {
- psmouse_reset(psmouse);
+ if (psmouse_reset(psmouse))
+ psmouse_err(psmouse, "psmouse_reset() failed.\n");
+
+
if (retry) {
/*
* On some boxes, right after resuming, the touchpad
--
1.7.8.6


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