Input: pmic8xxx-pwrkey - fix algorithm for converting trigger delay

commit eda5ecc0a6b865561997e177c393f0b0136fe3b7 upstream.

The trigger delay algorithm that converts from microseconds to
the register value looks incorrect. According to most of the PMIC
documentation, the equation is

	delay (Seconds) = (1 / 1024) * 2 ^ (x + 4)

except for one case where the documentation looks to have a
formatting issue and the equation looks like

	delay (Seconds) = (1 / 1024) * 2 x + 4

Most likely this driver was written with the improper
documentation to begin with. According to the downstream sources
the valid delays are from 2 seconds to 1/64 second, and the
latter equation just doesn't make sense for that. Let's fix the
algorithm and the range check to match the documentation and the
downstream sources.

Reported-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Fixes: 92d57a73e410 ("input: Add support for Qualcomm PMIC8XXX power key")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/input/misc/pmic8xxx-pwrkey.c b/drivers/input/misc/pmic8xxx-pwrkey.c
index c91e3d33aea90f0053717bad2c0594224bf8d1fb..88db9204bac2ea9d5b3fe59b14f845545db310c4 100644 (file)
--- a/drivers/input/misc/pmic8xxx-pwrkey.c
+++ b/drivers/input/misc/pmic8xxx-pwrkey.c
@@ -94,7 +94,8 @@ static int pmic8xxx_pwrkey_probe(struct platform_device *pdev)
        if (of_property_read_u32(pdev->dev.of_node, "debounce", &kpd_delay))
                kpd_delay = 15625;
 
-       if (kpd_delay > 62500 || kpd_delay == 0) {
+       /* Valid range of pwr key trigger delay is 1/64 sec to 2 seconds. */
+       if (kpd_delay > USEC_PER_SEC * 2 || kpd_delay < USEC_PER_SEC / 64) {
                dev_err(&pdev->dev, "invalid power key trigger delay\n");
                return -EINVAL;
        }
@@ -124,8 +125,8 @@ static int pmic8xxx_pwrkey_probe(struct platform_device *pdev)
        pwr->name = "pmic8xxx_pwrkey";
        pwr->phys = "pmic8xxx_pwrkey/input0";
 
-       delay = (kpd_delay << 10) / USEC_PER_SEC;
-       delay = 1 + ilog2(delay);
+       delay = (kpd_delay << 6) / USEC_PER_SEC;
+       delay = ilog2(delay);
 
        err = regmap_read(regmap, PON_CNTL_1, &pon_cntl);
        if (err < 0) {