On Fri, 14 Dec 2012, Shawn Nematbakhsh wrote:
> On resume from suspend there is a possibility for multi-byte scancodes
> to be handled incorrectly. atkbd_reconnect disables the processing of
> scancodes in software by calling atkbd_disable, but the keyboard may
> still be active because no disconnect command was sent. Later, software
> handling is re-enabled. If a multi-byte scancode sent from the keyboard
> straddles the re-enable, only the latter byte(s) will be handled.
>
> In practice, this leads to cases where multi-byte break codes (ex. "e0
> 4d" - break code for right-arrow) are misread as make codes ("4d" - make
> code for numeric 6), leading to one or more unwanted, untyped characters
> being interpreted.
>
> The solution implemented here involves sending command f5 (reset
> disable) to the keyboard prior to disabling software handling of codes.
> Later, the command to re-enable the keyboard is sent only after we are
> prepared to handle scancodes.
>
> Signed-off-by: Shawn Nematbakhsh <shawnn@xxxxxxxxxxxx>
> ---
> drivers/input/keyboard/atkbd.c | 26 ++++++++++++++++++++++++--
> 1 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c
> index add5ffd..da49e8b 100644
> --- a/drivers/input/keyboard/atkbd.c
> +++ b/drivers/input/keyboard/atkbd.c
> @@ -844,6 +844,24 @@ static int atkbd_activate(struct atkbd *atkbd)
> }
>
> /*
> + * atkbd_deactivate() resets and disables the keyboard from sending
> + * keystrokes.
> + */
> +static int atkbd_deactivate(struct atkbd *atkbd)
Why bother with a return type when you never check it anyway?
I'd say, either check for the 0/-1 you return and do something sensible or
just let it return void.
> +{
> + struct ps2dev *ps2dev = &atkbd->ps2dev;
> +
> + if (ps2_command(ps2dev, NULL, ATKBD_CMD_RESET_DIS)) {
> + dev_err(&ps2dev->serio->dev,
> + "Failed to deactivate keyboard on %s\n",
> + ps2dev->serio->phys);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +/*
> * atkbd_cleanup() restores the keyboard state so that BIOS is happy after a
> * reboot.
> */
> @@ -1199,6 +1217,9 @@ static int atkbd_reconnect(struct serio *serio)
>
> mutex_lock(&atkbd->mutex);
>
> + if (atkbd->write)
> + atkbd_deactivate(atkbd);
> +
> atkbd_disable(atkbd);
>
> if (atkbd->write) {
> @@ -1208,8 +1229,6 @@ static int atkbd_reconnect(struct serio *serio)
> if (atkbd->set != atkbd_select_set(atkbd, atkbd->set, atkbd->extra))
> goto out;
>
> - atkbd_activate(atkbd);
> -
> /*
> * Restore LED state and repeat rate. While input core
> * will do this for us at resume time reconnect may happen
> @@ -1224,6 +1243,9 @@ static int atkbd_reconnect(struct serio *serio)
> }
>
> atkbd_enable(atkbd);
> + if (atkbd->write)
> + atkbd_activate(atkbd);
> +
> retval = 0;
>
> out:
>
--
Jesper Juhl <jj@xxxxxxxxxxxxx> http://www.chaosbits.net/
Don't top-post http://www.catb.org/jargon/html/T/top-post.html
Plain text mails only, please.
--
To unsubscribe from this list: send the line "unsubscribe linux-input" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
