| Message ID | 20230511185252.386941-8-dmitry.torokhov@gmail.com (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | f219050af06d83f436945880fc9c04db3bb2860f |
| Headers | show |
| Series | libps2: be more tolerant when processing commands | expand |
On Thu, May 11, 2023 at 11:52:47AM -0700, Dmitry Torokhov wrote: > Upon receiving a PS/2 command the device and controller are supposed to > stop sending normal data (scancodes or movement packets) and instead > immediately start delivering ACK/NAK and command response. Unfortunately > often EC has an output buffer which may contain latched data by the time > the EC receives a command from the host. The kernel used to ignore such > data, but that may cause "stuck" keys if the data dropped happens to be a > break code or a part of a break code. This occasionally happens, for > example, on Chromebooks when the kernel tries to toggle CapsLock LED on > a keyboard while user releases Alt+Search keyboard shortcut. > > Fix this by passing the first non-ACK byte to the normal handler for a > handful of PS/2 commands that are expected to be used during normal device > operation (as opposed to probe/configuration time). > > Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> > --- > drivers/input/serio/libps2.c | 36 ++++++++++++++++++++++++++++++++---- > 1 file changed, 32 insertions(+), 4 deletions(-) > > diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c > index 7c5fc853072a..6d78a1fe00c1 100644 > --- a/drivers/input/serio/libps2.c > +++ b/drivers/input/serio/libps2.c > @@ -21,7 +21,10 @@ > > #define PS2_CMD_SETSCALE11 0x00e6 > #define PS2_CMD_SETRES 0x10e8 > +#define PS2_CMD_EX_SETLEDS 0x20eb > +#define PS2_CMD_SETLEDS 0x10ed > #define PS2_CMD_GETID 0x02f2 > +#define PS2_CMD_SETREP 0x10f3 /* Set repeat rate/set report rate */ > #define PS2_CMD_RESET_BAT 0x02ff > > #define PS2_RET_BAT 0xaa > @@ -35,6 +38,7 @@ > #define PS2_FLAG_CMD1 BIT(2) /* Waiting for the first byte of command response */ > #define PS2_FLAG_WAITID BIT(3) /* Command executing is GET ID */ > #define PS2_FLAG_NAK BIT(4) /* Last transmission was NAKed */ > +#define PS2_FLAG_PASS_NOACK BIT(5) /* Pass non-ACK byte to receive handler */ > > static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte, > unsigned int timeout, unsigned int max_attempts) > @@ -281,9 +285,28 @@ 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; > + > + switch (command) { > + case PS2_CMD_GETID: > + /* > + * Some mice do not ACK the "get ID" command, prepare to > + * handle this. > + */ > + ps2dev->flags = PS2_FLAG_WAITID; > + break; > + > + case PS2_CMD_SETLEDS: > + case PS2_CMD_EX_SETLEDS: > + case PS2_CMD_SETREP: > + ps2dev->flags = PS2_FLAG_PASS_NOACK; > + break; > + > + default: > + ps2dev->flags = 0; > + break; > + } > + > if (receive) { > /* Indicate that we expect response to the command. */ > ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1; > @@ -512,14 +535,19 @@ static void ps2_handle_ack(struct ps2dev *ps2dev, u8 data) > * Do not signal errors if we get unexpected reply while > * waiting for an ACK to the initial (first) command byte: > * the device might not be quiesced yet and continue > - * delivering data. > + * delivering data. For certain commands (such as set leds and > + * set repeat rate) that can be used during normal device > + * operation, we even pass this data byte to the normal receive > + * handler. > * Note that we reset PS2_FLAG_WAITID flag, so the workaround > * for mice not acknowledging the Get ID command only triggers > * on the 1st byte; if device spews data we really want to see > * a real ACK from it. > */ > dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data); > - ps2dev->flags &= ~PS2_FLAG_WAITID; > + if (ps2dev->flags & PS2_FLAG_PASS_NOACK) > + ps2dev->receive_handler(ps2dev, data); > + ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK); > return; > } > Great refactoring. It made this final patch super simple! Reviewed-by: Raul E Rangel <rrangel@chromium.org>
diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c index 7c5fc853072a..6d78a1fe00c1 100644 --- a/drivers/input/serio/libps2.c +++ b/drivers/input/serio/libps2.c @@ -21,7 +21,10 @@ #define PS2_CMD_SETSCALE11 0x00e6 #define PS2_CMD_SETRES 0x10e8 +#define PS2_CMD_EX_SETLEDS 0x20eb +#define PS2_CMD_SETLEDS 0x10ed #define PS2_CMD_GETID 0x02f2 +#define PS2_CMD_SETREP 0x10f3 /* Set repeat rate/set report rate */ #define PS2_CMD_RESET_BAT 0x02ff #define PS2_RET_BAT 0xaa @@ -35,6 +38,7 @@ #define PS2_FLAG_CMD1 BIT(2) /* Waiting for the first byte of command response */ #define PS2_FLAG_WAITID BIT(3) /* Command executing is GET ID */ #define PS2_FLAG_NAK BIT(4) /* Last transmission was NAKed */ +#define PS2_FLAG_PASS_NOACK BIT(5) /* Pass non-ACK byte to receive handler */ static int ps2_do_sendbyte(struct ps2dev *ps2dev, u8 byte, unsigned int timeout, unsigned int max_attempts) @@ -281,9 +285,28 @@ 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; + + switch (command) { + case PS2_CMD_GETID: + /* + * Some mice do not ACK the "get ID" command, prepare to + * handle this. + */ + ps2dev->flags = PS2_FLAG_WAITID; + break; + + case PS2_CMD_SETLEDS: + case PS2_CMD_EX_SETLEDS: + case PS2_CMD_SETREP: + ps2dev->flags = PS2_FLAG_PASS_NOACK; + break; + + default: + ps2dev->flags = 0; + break; + } + if (receive) { /* Indicate that we expect response to the command. */ ps2dev->flags |= PS2_FLAG_CMD | PS2_FLAG_CMD1; @@ -512,14 +535,19 @@ static void ps2_handle_ack(struct ps2dev *ps2dev, u8 data) * Do not signal errors if we get unexpected reply while * waiting for an ACK to the initial (first) command byte: * the device might not be quiesced yet and continue - * delivering data. + * delivering data. For certain commands (such as set leds and + * set repeat rate) that can be used during normal device + * operation, we even pass this data byte to the normal receive + * handler. * Note that we reset PS2_FLAG_WAITID flag, so the workaround * for mice not acknowledging the Get ID command only triggers * on the 1st byte; if device spews data we really want to see * a real ACK from it. */ dev_dbg(&ps2dev->serio->dev, "unexpected %#02x\n", data); - ps2dev->flags &= ~PS2_FLAG_WAITID; + if (ps2dev->flags & PS2_FLAG_PASS_NOACK) + ps2dev->receive_handler(ps2dev, data); + ps2dev->flags &= ~(PS2_FLAG_WAITID | PS2_FLAG_PASS_NOACK); return; }
Upon receiving a PS/2 command the device and controller are supposed to stop sending normal data (scancodes or movement packets) and instead immediately start delivering ACK/NAK and command response. Unfortunately often EC has an output buffer which may contain latched data by the time the EC receives a command from the host. The kernel used to ignore such data, but that may cause "stuck" keys if the data dropped happens to be a break code or a part of a break code. This occasionally happens, for example, on Chromebooks when the kernel tries to toggle CapsLock LED on a keyboard while user releases Alt+Search keyboard shortcut. Fix this by passing the first non-ACK byte to the normal handler for a handful of PS/2 commands that are expected to be used during normal device operation (as opposed to probe/configuration time). Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> --- drivers/input/serio/libps2.c | 36 ++++++++++++++++++++++++++++++++---- 1 file changed, 32 insertions(+), 4 deletions(-)