linux-kernel - [RFC PATCH 2/8] drm/edid: Break out reading block 0 of the EDID

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Message-Id: <20210722172104.RFC.2.I62e76a034ac78c994d40a23cd4ec5aeee56fa77c@changeid>
Date:   Thu, 22 Jul 2021 17:21:40 -0700
From:   Douglas Anderson <dianders@...omium.org>
To:     Thierry Reding <thierry.reding@...il.com>,
        Rob Herring <robh+dt@...nel.org>
Cc:     Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Steev Klimaszewski <steev@...i.org>,
        dri-devel@...ts.freedesktop.org, David Airlie <airlied@...ux.ie>,
        devicetree@...r.kernel.org, Daniel Vetter <daniel@...ll.ch>,
        Maxime Ripard <mripard@...nel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        linux-arm-msm@...r.kernel.org, Linus W <linus.walleij@...aro.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Douglas Anderson <dianders@...omium.org>,
        linux-kernel@...r.kernel.org
Subject: [RFC PATCH 2/8] drm/edid: Break out reading block 0 of the EDID

A future change wants to be able to read just block 0 of the EDID, so
break it out of drm_do_get_edid() into a sub-function.

This is intended to be a no-op change--just code movement.

Signed-off-by: Douglas Anderson <dianders@...omium.org>
---

 drivers/gpu/drm/drm_edid.c | 62 +++++++++++++++++++++++++++-----------
 1 file changed, 44 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 81d5f2524246..a623a80f7edb 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1905,6 +1905,43 @@ int drm_add_override_edid_modes(struct drm_connector *connector)
 }
 EXPORT_SYMBOL(drm_add_override_edid_modes);
 
+static struct edid *drm_do_get_edid_blk0(
+	int (*get_edid_block)(void *data, u8 *buf, unsigned int block,
+			      size_t len),
+	void *data, bool *edid_corrupt, int *null_edid_counter)
+{
+	int i;
+	u8 *edid;
+
+	if ((edid = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
+		return NULL;
+
+	/* base block fetch */
+	for (i = 0; i < 4; i++) {
+		if (get_edid_block(data, edid, 0, EDID_LENGTH))
+			goto out;
+		if (drm_edid_block_valid(edid, 0, false, edid_corrupt))
+			break;
+		if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) {
+			if (null_edid_counter)
+				(*null_edid_counter)++;
+			goto carp;
+		}
+	}
+	if (i == 4)
+		goto carp;
+
+	return (struct edid *)edid;
+
+carp:
+	kfree(edid);
+	return ERR_PTR(-EINVAL);
+
+out:
+	kfree(edid);
+	return NULL;
+}
+
 /**
  * drm_do_get_edid - get EDID data using a custom EDID block read function
  * @connector: connector we're probing
@@ -1938,25 +1975,16 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 	if (override)
 		return override;
 
-	if ((edid = kmalloc(EDID_LENGTH, GFP_KERNEL)) == NULL)
+	edid = (u8 *)drm_do_get_edid_blk0(get_edid_block, data,
+					  &connector->edid_corrupt,
+					  &connector->null_edid_counter);
+	if (IS_ERR_OR_NULL(edid)) {
+		if (IS_ERR(edid))
+			connector_bad_edid(connector, edid, 1);
 		return NULL;
-
-	/* base block fetch */
-	for (i = 0; i < 4; i++) {
-		if (get_edid_block(data, edid, 0, EDID_LENGTH))
-			goto out;
-		if (drm_edid_block_valid(edid, 0, false,
-					 &connector->edid_corrupt))
-			break;
-		if (i == 0 && drm_edid_is_zero(edid, EDID_LENGTH)) {
-			connector->null_edid_counter++;
-			goto carp;
-		}
 	}
-	if (i == 4)
-		goto carp;
 
-	/* if there's no extensions, we're done */
+	/* if there's no extensions or no connector, we're done */
 	valid_extensions = edid[0x7e];
 	if (valid_extensions == 0)
 		return (struct edid *)edid;
@@ -2010,8 +2038,6 @@ struct edid *drm_do_get_edid(struct drm_connector *connector,
 
 	return (struct edid *)edid;
 
-carp:
-	connector_bad_edid(connector, edid, 1);
 out:
 	kfree(edid);
 	return NULL;
-- 
2.32.0.432.gabb21c7263-goog