diff mbox series

[v6,2/9] drm/i915/dpcd_bl: Handle drm_dpcd_read/write() return values correctly

Message ID 20210514181504.565252-3-lyude@redhat.com (mailing list archive)
State New, archived
Headers show
Series drm: Extract DPCD backlight helpers from i915, add support in nouveau | expand

Commit Message

Lyude Paul May 14, 2021, 6:14 p.m. UTC 
This is kind of an annoying aspect of DRM's DP helpers:
drm_dp_dpcd_readb/writeb() return the size of bytes read/written on
success, thus we want to check against that instead of checking if the
return value is less than 0.

I'll probably be fixing this in the near future once I start doing DP work
again, also because I'd rather not mix a tree-wide refactor like that in
with a patch series intended to be around introducing DP backlight helpers.
So, for now let's just handle the return values from each function
correctly.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
---
 .../drm/i915/display/intel_dp_aux_backlight.c | 41 +++++++++----------
 1 file changed, 19 insertions(+), 22 deletions(-)
diff mbox series

Patch

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 68bfe50ada59..1dbe38282ebe 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c
@@ -107,7 +107,7 @@  intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
 	u8 tcon_cap[4];
 
 	ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
-	if (ret < 0)
+	if (ret != sizeof(tcon_cap))
 		return false;
 
 	if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
@@ -137,7 +137,7 @@  intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe
 	u8 tmp;
 	u8 buf[2] = { 0 };
 
-	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) < 0) {
+	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) != 1) {
 		drm_err(&i915->drm, "Failed to read current backlight mode from DPCD\n");
 		return 0;
 	}
@@ -153,7 +153,8 @@  intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe
 		return panel->backlight.max;
 	}
 
-	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf, sizeof(buf)) < 0) {
+	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
+			     sizeof(buf)) != sizeof(buf)) {
 		drm_err(&i915->drm, "Failed to read brightness from DPCD\n");
 		return 0;
 	}
@@ -172,7 +173,8 @@  intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state,
 	buf[0] = level & 0xFF;
 	buf[1] = (level & 0xFF00) >> 8;
 
-	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf, 4) < 0)
+	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
+			      sizeof(buf)) != sizeof(buf))
 		drm_err(dev, "Failed to write brightness level to DPCD\n");
 }
 
@@ -203,7 +205,7 @@  intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
 	u8 old_ctrl, ctrl;
 
 	ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
-	if (ret < 0) {
+	if (ret != 1) {
 		drm_err(&i915->drm, "Failed to read current backlight control mode: %d\n", ret);
 		return;
 	}
@@ -221,7 +223,7 @@  intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
 	}
 
 	if (ctrl != old_ctrl)
-		if (drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) < 0)
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
 			drm_err(&i915->drm, "Failed to configure DPCD brightness controls\n");
 }
 
@@ -277,8 +279,7 @@  static void set_vesa_backlight_enable(struct intel_dp *intel_dp, bool enable)
 	if (!(intel_dp->edp_dpcd[1] & DP_EDP_BACKLIGHT_AUX_ENABLE_CAP))
 		return;
 
-	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER,
-			      &reg_val) < 0) {
+	if (drm_dp_dpcd_readb(&intel_dp->aux, DP_EDP_DISPLAY_CONTROL_REGISTER, &reg_val) != 1) {
 		drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
 			    DP_EDP_DISPLAY_CONTROL_REGISTER);
 		return;
@@ -332,8 +333,8 @@  static u32 intel_dp_aux_vesa_get_backlight(struct intel_connector *connector, en
 	if (!intel_dp_aux_vesa_backlight_dpcd_mode(connector))
 		return connector->panel.backlight.max;
 
-	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
-			     &read_val, sizeof(read_val)) < 0) {
+	if (drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, &read_val,
+			     sizeof(read_val)) != sizeof(read_val)) {
 		drm_dbg_kms(&i915->drm, "Failed to read DPCD register 0x%x\n",
 			    DP_EDP_BACKLIGHT_BRIGHTNESS_MSB);
 		return 0;
@@ -365,8 +366,8 @@  intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state,
 		vals[0] = (level & 0xFF00) >> 8;
 		vals[1] = (level & 0xFF);
 	}
-	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB,
-			      vals, sizeof(vals)) < 0) {
+	if (drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_BACKLIGHT_BRIGHTNESS_MSB, vals,
+			      sizeof(vals)) != sizeof(vals)) {
 		drm_dbg_kms(&i915->drm,
 			    "Failed to write aux backlight level\n");
 		return;
@@ -401,9 +402,8 @@  intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 		new_dpcd_buf &= ~DP_EDP_BACKLIGHT_CONTROL_MODE_MASK;
 		new_dpcd_buf |= DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD;
 
-		if (drm_dp_dpcd_writeb(&intel_dp->aux,
-				       DP_EDP_PWMGEN_BIT_COUNT,
-				       pwmgen_bit_count) < 0)
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT,
+				       pwmgen_bit_count) != 1)
 			drm_dbg_kms(&i915->drm,
 				    "Failed to write aux pwmgen bit count\n");
 
@@ -424,11 +424,9 @@  intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
 	}
 
 	if (new_dpcd_buf != dpcd_buf) {
-		if (drm_dp_dpcd_writeb(&intel_dp->aux,
-			DP_EDP_BACKLIGHT_MODE_SET_REGISTER, new_dpcd_buf) < 0) {
-			drm_dbg_kms(&i915->drm,
-				    "Failed to write aux backlight mode\n");
-		}
+		if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
+				       new_dpcd_buf) != 1)
+			drm_dbg_kms(&i915->drm, "Failed to write aux backlight mode\n");
 	}
 
 	intel_dp_aux_vesa_set_backlight(conn_state, level);
@@ -519,8 +517,7 @@  static u32 intel_dp_aux_vesa_calc_max_backlight(struct intel_connector *connecto
 	}
 
 	drm_dbg_kms(&i915->drm, "Using eDP pwmgen bit count of %d\n", pn);
-	if (drm_dp_dpcd_writeb(&intel_dp->aux,
-			       DP_EDP_PWMGEN_BIT_COUNT, pn) < 0) {
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_PWMGEN_BIT_COUNT, pn) != 1) {
 		drm_dbg_kms(&i915->drm,
 			    "Failed to write aux pwmgen bit count\n");
 		return max_backlight;