Commit 17917ff6 authored by Lyude Paul's avatar Lyude Paul
Browse files

drm/i915/dpcd_bl: Return early in vesa_calc_max_backlight if we can't read PWMGEN_BIT_COUNT 



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: default avatarLyude Paul <lyude@redhat.com>
Reviewed-by: default avatarRodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210514181504.565252-7-lyude@redhat.com
parent ade673bb

drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c

+6 −3
Original line number Diff line number Diff line
@@ -449,10 +449,13 @@ 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) {

	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