drm/meson: add mode selection limits against specific SoC revisions

The Amlogic S805X/Y uses the same die as the S905X, but with more
limited graphics capabilities.

This adds a soc version detection adding specific limitations on the HDMI
mode selections.

Here, we limit to HDMI 1.2a max HDMI PHY clock frequency.

Changes sinces v1:
- Moved frequency check in the vclk code, and also checks DMT modes

Signed-off-by: Neil Armstrong <[e-mail]>
Acked-by: Martin Blumenstingl <[e-mail]>
[narmstrong: fixed commit message with HDMI 1.2a instead of HDMI 1.3a]
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/meson/meson_drv.c

···
 #include <linux/component.h>
 #include <linux/module.h>
 #include <linux/of_graph.h>
+#include <linux/sys_soc.h>
 #include <linux/platform_device.h>
 #include <linux/soc/amlogic/meson-canvas.h>
 
···
 	kfree(ap);
 }
 
+struct meson_drm_soc_attr {
+	struct meson_drm_soc_limits limits;
+	const struct soc_device_attribute *attrs;
+};
+
+static const struct meson_drm_soc_attr meson_drm_soc_attrs[] = {
+	/* S805X/S805Y HDMI PLL won't lock for HDMI PHY freq > 1,65GHz */
+	{
+		.limits = {
+			.max_hdmi_phy_freq = 1650000,
+		},
+		.attrs = (const struct soc_device_attribute []) {
+			{ .soc_id = "GXL (S805*)", },
+			{ /* sentinel */ },
+		}
+	},
+};
+
 static int meson_drv_bind_master(struct device *dev, bool has_components)
 {
 	struct platform_device *pdev = to_platform_device(dev);
···
 	struct drm_device *drm;
 	struct resource *res;
 	void __iomem *regs;
-	int ret;
+	int ret, i;
 
 	/* Checks if an output connector is available */
 	if (!meson_vpu_has_available_connectors(dev)) {
···
 	ret = drm_vblank_init(drm, 1);
 	if (ret)
 		goto free_drm;
+
+	/* Assign limits per soc revision/package */
+	for (i = 0 ; i < ARRAY_SIZE(meson_drm_soc_attrs) ; ++i) {
+		if (soc_device_match(meson_drm_soc_attrs[i].attrs)) {
+			priv->limits = &meson_drm_soc_attrs[i].limits;
+			break;
+		}
+	}
 
 	/* Remove early framebuffers (ie. simplefb) */
 	meson_remove_framebuffers();

drivers/gpu/drm/meson/meson_drv.h

···
 	struct meson_afbcd_ops *afbcd_ops;
 };
 
+struct meson_drm_soc_limits {
+	unsigned int max_hdmi_phy_freq;
+};
+
 struct meson_drm {
 	struct device *dev;
 	enum vpu_compatible compat;
···
 	struct drm_crtc *crtc;
 	struct drm_plane *primary_plane;
 	struct drm_plane *overlay_plane;
+
+	const struct meson_drm_soc_limits *limits;
 
 	/* Components Data */
 	struct {

drivers/gpu/drm/meson/meson_dw_hdmi.c

···
 	dev_dbg(connector->dev->dev, "%s: vclk:%d phy=%d venc=%d hdmi=%d\n",
 		__func__, phy_freq, vclk_freq, venc_freq, hdmi_freq);
 
-	return meson_vclk_vic_supported_freq(phy_freq, vclk_freq);
+	return meson_vclk_vic_supported_freq(priv, phy_freq, vclk_freq);
 }
 
 /* Encoder */

drivers/gpu/drm/meson/meson_vclk.c

···
 	/* In DMT mode, path after PLL is always /10 */
 	freq *= 10;
 
+	/* Check against soc revision/package limits */
+	if (priv->limits) {
+		if (priv->limits->max_hdmi_phy_freq &&
+		    freq > priv->limits->max_hdmi_phy_freq)
+			return MODE_CLOCK_HIGH;
+	}
+
 	if (meson_hdmi_pll_find_params(priv, freq, &m, &frac, &od))
 		return MODE_OK;
 
···
 }
 
 enum drm_mode_status
-meson_vclk_vic_supported_freq(unsigned int phy_freq,
+meson_vclk_vic_supported_freq(struct meson_drm *priv, unsigned int phy_freq,
 			      unsigned int vclk_freq)
 {
 	int i;
 
 	DRM_DEBUG_DRIVER("phy_freq = %d vclk_freq = %d\n",
 			 phy_freq, vclk_freq);
+
+	/* Check against soc revision/package limits */
+	if (priv->limits) {
+		if (priv->limits->max_hdmi_phy_freq &&
+		    phy_freq > priv->limits->max_hdmi_phy_freq)
+			return MODE_CLOCK_HIGH;
+	}
 
 	for (i = 0 ; params[i].pixel_freq ; ++i) {
 		DRM_DEBUG_DRIVER("i = %d pixel_freq = %d alt = %d\n",

drivers/gpu/drm/meson/meson_vclk.h

···
 enum drm_mode_status
 meson_vclk_dmt_supported_freq(struct meson_drm *priv, unsigned int freq);
 enum drm_mode_status
-meson_vclk_vic_supported_freq(unsigned int phy_freq, unsigned int vclk_freq);
+meson_vclk_vic_supported_freq(struct meson_drm *priv, unsigned int phy_freq,
+			      unsigned int vclk_freq);
 
 void meson_vclk_setup(struct meson_drm *priv, unsigned int target,
 		      unsigned int phy_freq, unsigned int vclk_freq,