panasonic-laptop driver oddity

panasonic-laptop driver oddity

[Andy Whitcroft]

We have been looking at your panasonic-laptop driver with a view to
back porting it to 2.6.27, and the following inconsistancy was pointed
out to me.  In bl_set_status() we ensure that bright is no lower than
sinf[SINF_AC_MIN_BRIGHT] and sinf[SINF_DC_MIN_BRIGHT], and then check if
it is lower than sinf[SINF_AC_MIN_BRIGHT].  That seems redundant.


    static int bl_set_status(struct backlight_device *bd)
    {
        struct pcc_acpi *pcc = bl_get_data(bd);
        int bright = bd->props.brightness;
        int rc;

        if (!acpi_pcc_retrieve_biosdata(pcc, pcc->sinf))
                return -EIO;

        if (bright < pcc->sinf[SINF_AC_MIN_BRIGHT])
                bright = pcc->sinf[SINF_AC_MIN_BRIGHT];

        if (bright < pcc->sinf[SINF_DC_MIN_BRIGHT])
                bright = pcc->sinf[SINF_DC_MIN_BRIGHT];

        if (bright < pcc->sinf[SINF_AC_MIN_BRIGHT] ||
            bright > pcc->sinf[SINF_AC_MAX_BRIGHT])
                return -EINVAL;

We could not decide if this was simply belt and braces to constrain the
value, or if this should be a check against sinf[SINF_DC_MAX_BRIGHT].
Perhaps you could clarify?

-apw