2023-05-11 18:55:32

by Dmitry Torokhov

Subject: [PATCH 3/7] Input: libps2 - rework handling of command response

It is not entirely correct that libps2 sets PS2_FLAG_CMD1 after
the device acknowledges each byte sent to the device by the host.
Rework the code so that PS2_FLAG_CMD1 and PS2_FLAG_CMD are set only once,
at the beginning of PS/2 command execution.

Signed-off-by: Dmitry Torokhov <[email protected]>
---
drivers/input/serio/libps2.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 399cda0d34f5..d09450eca9a7 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -247,14 +247,19 @@ int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)

serio_pause_rx(ps2dev->serio);

+ /* Some mice do not ACK the "get ID" command, prepare to handle this. */
ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
ps2dev->cmdcnt = receive;
- if (receive && param)
- for (i = 0; i < receive; i++)
- ps2dev->cmdbuf[(receive - 1) - i] = param[i];
+ if (receive) {
+ /* Indicate that we expect response to the command. */
+ ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
+ if (param)
+ for (i = 0; i < receive; i++)
+ ps2dev->cmdbuf[(receive - 1) - i] = param[i];
+ }

/*
- * Some devices (Synaptics) peform the reset before
+ * Some devices (Synaptics) perform the reset before
* ACKing the reset command, and so it can take a long
* time before the ACK arrives.
*/
@@ -434,11 +439,8 @@ bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
return true;
}

- if (!ps2dev->nak) {
+ if (!ps2dev->nak)
ps2dev->flags &= ~PS2_FLAG_NAK;
- if (ps2dev->cmdcnt)
- ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
- }

ps2dev->flags &= ~PS2_FLAG_ACK;
wake_up(&ps2dev->wait);
--
2.40.1.606.ga4b1b128d6-goog

2023-05-18 17:29:51

by Raul Rangel

Subject: Re: [PATCH 3/7] Input: libps2 - rework handling of command response

On Thu, May 11, 2023 at 11:52:43AM -0700, Dmitry Torokhov wrote:
> It is not entirely correct that libps2 sets PS2_FLAG_CMD1 after
> the device acknowledges each byte sent to the device by the host.
> Rework the code so that PS2_FLAG_CMD1 and PS2_FLAG_CMD are set only once,
> at the beginning of PS/2 command execution.
>
> Signed-off-by: Dmitry Torokhov <[email protected]>
> ---
> drivers/input/serio/libps2.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
> index 399cda0d34f5..d09450eca9a7 100644
> --- a/drivers/input/serio/libps2.c
> +++ b/drivers/input/serio/libps2.c
> @@ -247,14 +247,19 @@ int __ps2_command(struct ps2dev *ps2dev, u8 *param, unsigned int command)
>
> serio_pause_rx(ps2dev->serio);
>
> + /* Some mice do not ACK the "get ID" command, prepare to handle this. */
> ps2dev->flags = command == PS2_CMD_GETID ? PS2_FLAG_WAITID : 0;
> ps2dev->cmdcnt = receive;
> - if (receive && param)
> - for (i = 0; i < receive; i++)
> - ps2dev->cmdbuf[(receive - 1) - i] = param[i];
> + if (receive) {
> + /* Indicate that we expect response to the command. */
> + ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
> + if (param)
> + for (i = 0; i < receive; i++)
> + ps2dev->cmdbuf[(receive - 1) - i] = param[i];
> + }
>
> /*
> - * Some devices (Synaptics) peform the reset before
> + * Some devices (Synaptics) perform the reset before
> * ACKing the reset command, and so it can take a long
> * time before the ACK arrives.
> */
> @@ -434,11 +439,8 @@ bool ps2_handle_ack(struct ps2dev *ps2dev, u8 data)
> return true;
> }
>
> - if (!ps2dev->nak) {
> + if (!ps2dev->nak)
> ps2dev->flags &= ~PS2_FLAG_NAK;
> - if (ps2dev->cmdcnt)
> - ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1;
> - }
>
> ps2dev->flags &= ~PS2_FLAG_ACK;
> wake_up(&ps2dev->wait);
Reviewed-by: Raul E Rangel <[email protected]>