[PATCH v5 phy-next 11/27] drm/rockchip: dw_hdmi: avoid direct dereference of phy->dev.of_node

[Vladimir Oltean <vladimir.oltean@nxp.com>]

The dw_hdmi-rockchip driver validates pixel clock rates against the
HDMI PHY's internal clock provider on certain SoCs like RK3328.
This is currently achieved by dereferencing hdmi->phy->dev.of_node
to obtain the provider node, which violates the Generic PHY API's
encapsulation (the goal is for struct phy to be an opaque pointer
with a hidden definition, to be interacted with only using API
functions or NULL pointer checks, for the case where optional variants
of phy_get() did not find a PHY).

Refactor dw_hdmi_rockchip_bind() to perform a manual phandle lookup
on the "hdmi" PHY index within the controller's DT node. This provides
a parallel path to the clock provider's OF node without relying on the
internal structure of the struct phy handle.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Heiko Stueber <heiko@sntech.de>
---
Cc: Sandy Huang <hjc@rock-chips.com>
Cc: "Heiko Stübner" <heiko@sntech.de>
Cc: Andy Yan <andy.yan@rock-chips.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>

v4->v5: none
v3->v4: add commit message clarification of what is understood by
        "opaque pointer"
v1->v3: none
---
 drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c | 25 ++++++++++++---------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
index 0dc1eb5d2ae3..7abb42e486c0 100644
--- a/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
+++ b/drivers/gpu/drm/rockchip/dw_hdmi-rockchip.c
@@ -537,21 +537,22 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 				 void *data)
 {
 	struct platform_device *pdev = to_platform_device(dev);
+	struct device_node *np = dev_of_node(dev);
 	struct dw_hdmi_plat_data *plat_data;
 	const struct of_device_id *match;
 	struct drm_device *drm = data;
 	struct drm_encoder *encoder;
 	struct rockchip_hdmi *hdmi;
-	int ret;
+	int ret, index;
 
-	if (!pdev->dev.of_node)
+	if (!np)
 		return -ENODEV;
 
 	hdmi = devm_kzalloc(&pdev->dev, sizeof(*hdmi), GFP_KERNEL);
 	if (!hdmi)
 		return -ENOMEM;
 
-	match = of_match_node(dw_hdmi_rockchip_dt_ids, pdev->dev.of_node);
+	match = of_match_node(dw_hdmi_rockchip_dt_ids, np);
 	plat_data = devm_kmemdup(&pdev->dev, match->data,
 					     sizeof(*plat_data), GFP_KERNEL);
 	if (!plat_data)
@@ -564,9 +565,9 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 	plat_data->priv_data = hdmi;
 	encoder = &hdmi->encoder.encoder;
 
-	encoder->possible_crtcs = drm_of_find_possible_crtcs(drm, dev->of_node);
+	encoder->possible_crtcs = drm_of_find_possible_crtcs(drm, np);
 	rockchip_drm_encoder_set_crtc_endpoint_id(&hdmi->encoder,
-						  dev->of_node, 0, 0);
+						  np, 0, 0);
 
 	/*
 	 * If we failed to find the CRTC(s) which this encoder is
@@ -588,13 +589,17 @@ static int dw_hdmi_rockchip_bind(struct device *dev, struct device *master,
 		return dev_err_probe(hdmi->dev, ret, "failed to get phy\n");
 	}
 
-	if (hdmi->phy) {
+	index = of_property_match_string(np, "phy-names", "hdmi");
+	if (index >= 0) {
 		struct of_phandle_args clkspec;
 
-		clkspec.np = hdmi->phy->dev.of_node;
-		hdmi->hdmiphy_clk = of_clk_get_from_provider(&clkspec);
-		if (IS_ERR(hdmi->hdmiphy_clk))
-			hdmi->hdmiphy_clk = NULL;
+		if (!of_parse_phandle_with_args(np, "phys", "#phy-cells", index,
+						&clkspec)) {
+			hdmi->hdmiphy_clk = of_clk_get_from_provider(&clkspec);
+			of_node_put(clkspec.np);
+			if (IS_ERR(hdmi->hdmiphy_clk))
+				hdmi->hdmiphy_clk = NULL;
+		}
 	}
 
 	if (hdmi->chip_data == &rk3568_chip_data) {
-- 
2.43.0