Re: [PATCH v2 1/2] Input: i8042 - Prevent intermixing i8042 commands
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2020-12-07 06:41:39
Also in:
linux-leds, lkml, platform-driver-x86
Subsystem:
input (keyboard, mouse, joystick, touchscreen) drivers, the rest · Maintainers:
Dmitry Torokhov, Linus Torvalds
Hi Raul, On Thu, Aug 27, 2020 at 02:41:53PM -0600, Raul E Rangel wrote:
The i8042_mutex must be held by writers of the AUX and KBD ports, as well as users of i8042_command. There were a lot of users of i8042_command that were not calling i8042_lock_chip/i8042_unlock_chip. This resulted in i8042_commands being issues in between PS/2 transactions. This change moves the mutex lock into i8042_command and removes the burden of locking the mutex from the callers.
I think there is a benefit for allowing users issue a sequence of commands to i8042 without interruptions, so I would prefer keeping i8042_[un]lock_chip() in place. Given that the issue you were observing was caused by i8042_port_close() interfering with probing, maybe we could do something like this:
diff --git a/drivers/input/serio/i8042.c b/drivers/input/serio/i8042.c
index abae23af0791..aff871001eda 100644
--- a/drivers/input/serio/i8042.c
+++ b/drivers/input/serio/i8042.c@@ -344,6 +344,8 @@ int i8042_command(unsigned char *param, int command) unsigned long flags; int retval; + lockdep_assert_held(&i8042_mutex); + if (!i8042_present) return -1;
@@ -364,6 +366,8 @@ static int i8042_kbd_write(struct serio *port, unsigned char c) unsigned long flags; int retval = 0; + lockdep_assert_held(&i8042_mutex); + spin_lock_irqsave(&i8042_lock, flags); if (!(retval = i8042_wait_write())) {
@@ -411,6 +415,8 @@ static void i8042_port_close(struct serio *serio) port_name = "KBD"; } + i8042_lock_chip(); + i8042_ctr &= ~irq_bit; if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) pr_warn("Can't write CTR while closing %s port\n", port_name);
@@ -422,6 +428,8 @@ static void i8042_port_close(struct serio *serio) if (i8042_command(&i8042_ctr, I8042_CMD_CTL_WCTR)) pr_err("Can't reactivate %s port\n", port_name); + i8042_unlock_chip(); + /* * See if there is any data appeared while we were messing with * port state.
Thanks. -- Dmitry