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Commit c23bb602 authored by Russell King's avatar Russell King
Browse files

MFD: ucb1x00-core: fix gpiolib direction_output handling 



gpiolib drivers should first set the output data before setting the
direction to avoid putting glitches on an output signal.  As an
additional bonus, we tweak the code to avoid unnecessary register
writes to the output and direction registers if they have no need
to be updated.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 2e95e51e

drivers/mfd/ucb1x00-core.c

+12 −6
Original line number Diff line number Diff line
@@ -148,16 +148,22 @@ static int ucb1x00_gpio_direction_output(struct gpio_chip *chip, unsigned offset 
{

	struct ucb1x00 *ucb = container_of(chip, struct ucb1x00, gpio);

	unsigned long flags;

	unsigned old, mask = 1 << offset;



	spin_lock_irqsave(&ucb->io_lock, flags);

	ucb->io_dir |= (1 << offset);

	ucb1x00_reg_write(ucb, UCB_IO_DIR, ucb->io_dir);



	old = ucb->io_out;

	if (value)

		ucb->io_out |= 1 << offset;

		ucb->io_out |= mask;

	else

		ucb->io_out &= ~(1 << offset);

		ucb->io_out &= ~mask;



	if (old != ucb->io_out)

		ucb1x00_reg_write(ucb, UCB_IO_DATA, ucb->io_out);



	if (!(ucb->io_dir & mask)) {

		ucb->io_dir |= mask;

		ucb1x00_reg_write(ucb, UCB_IO_DIR, ucb->io_dir);

	}

	spin_unlock_irqrestore(&ucb->io_lock, flags);



	return 0;