If we can't read DP_EDP_PWMGEN_BIT_COUNT in intel_dp_aux_vesa_calc_max_backlight() but do have a valid PWM frequency defined in the VBT, we'll keep going in the function until we inevitably fail on reading DP_EDP_PWMGEN_BIT_COUNT_CAP_MIN. There's not much point in doing this, so just return early.
Signed-off-by: Lyude Paul lyude@redhat.com --- drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c index 431758058aa0..c66350cdf7e9 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c @@ -449,11 +449,14 @@ static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto int freq, fxp, fxp_min, fxp_max, fxp_actual, f = 1; u8 pn, pn_min, pn_max;
- if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, &pn) == 1) { - pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK; - max_backlight = (1 << pn) - 1; + if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, &pn) != 1) { + drm_dbg_kms(&i915->drm, "Failed to read pwmgen bit count cap\n"); + return 0; }
+ pn &= DP_EDP_PWMGEN_BIT_COUNT_MASK; + max_backlight = (1 << pn) - 1; + /* Find desired value of (F x P) * Note that, if F x P is out of supported range, the maximum value or * minimum value will applied automatically. So no need to check that.