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    SubjectRe: [PATCH 1/2] input: adp5588-keys - get value from data out when dir out
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    On Apr 21, 2012, at 2:47, Dmitry Torokhov wrote:

    > Hi Jean-François,
    >
    > On Fri, Apr 20, 2012 at 11:32:00AM -0400, Jean-François Dagenais wrote:
    >> As discussed here: http://ez.analog.com/message/35852,
    >> the 5587 revC and 5588 revB spec sheets contain a mistake
    >> in the GPIO_DAT_STATx register description.
    >>
    >> According to R.Shnell at ADI, as well as my own
    >> observations, it should read:
    >> "GPIO data status (shows GPIO state when read for inputs)".
    >>
    >> This commit changes the get value function accordingly.
    >>
    >> A similar patch for gpio-adp5588 follows.
    >>
    >> Signed-off-by: Jean-François Dagenais <jeff.dagenais@gmail.com>
    >> Acked-by: Michael Hennerich <michael.hennerich@analog.com>
    >> ---
    >> drivers/input/keyboard/adp5588-keys.c | 7 +++++++
    >> 1 files changed, 7 insertions(+), 0 deletions(-)
    >>
    >> diff --git a/drivers/input/keyboard/adp5588-keys.c b/drivers/input/keyboard/adp5588-keys.c
    >> index 6412ced..b7a0f1a 100644
    >> --- a/drivers/input/keyboard/adp5588-keys.c
    >> +++ b/drivers/input/keyboard/adp5588-keys.c
    >> @@ -78,6 +78,13 @@ static int adp5588_gpio_get_value(struct gpio_chip *chip, unsigned off)
    >> unsigned int bank = ADP5588_BANK(kpad->gpiomap[off]);
    >> unsigned int bit = ADP5588_BIT(kpad->gpiomap[off]);
    >>
    >> + mutex_lock(&kpad->gpio_lock);
    >> + if (kpad->dir[bank] & bit) {
    >> + int result = !!(kpad->dat_out[bank] & bit);
    >> + mutex_unlock(&kpad->gpio_lock);
    >> + return result;
    >> + }
    >> + mutex_unlock(&kpad->gpio_lock);
    >> return !!(adp5588_read(kpad->client, GPIO_DAT_STAT1 + bank) & bit);
    >
    > This locking looks wrong as it is possible for adp5588_gpio_get_value()
    > to get scheduled out after checking kpad->dir[bank] and releasing
    > kpad->gpio_lock while another thread executes
    > adp5588_gpio_direction_output() and modifies kpad->dir[bank].
    >
    > You should keep mutex for the entire duration; something like this:
    >
    > mutex_lock(&kpad->gpio_lock);
    > if (kpad->dir[bank] & bit)
    > val = kpad->dat_out[bank];
    > else
    > val = adp5588_read(kpad->client, GPIO_DAT_STAT1 + bank);
    > mutex_unlock(&kpad->gpio_lock);
    >
    > return !!(val & bit);
    >
    Agreed, I think I wanted to minimize refactoring a bit too much and got distracted. I will send V2 shortly for both drivers.
    > Thanks.
    Thank you!
    >
    > --
    > Dmitry

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