Re: [PATCH] drm/meson: add mode selection limits against specific SoC revisions

[Daniel Vetter]

On Tue, Apr 21, 2020 at 03:44:10PM +0200, Neil Armstrong wrote:
> 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 1.3a max HDMI PHY clock frequency.
> 
> Signed-off-by: Neil Armstrong <narmstrong@xxxxxxxxxxxx>

Just a drive-by, but the code organization between the dw-hdmi bridge and
the driver looks pretty terribly and really leaky. Can't we do better?
Either by fixing the dw-hdmi bridge abstraction to actually abstract
something, or by givin up the dw-hdmi is a bridge and convert it to some
helper to implement a drm_encoder. Current status just doesn't make too
much sense to me.
-Daniel

> ---
>  drivers/gpu/drm/meson/meson_drv.c     | 29 ++++++++++++++++++++++++++-
>  drivers/gpu/drm/meson/meson_drv.h     |  6 ++++++
>  drivers/gpu/drm/meson/meson_dw_hdmi.c |  7 +++++++
>  3 files changed, 41 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
> index 6f29fab79952..621f6de0f076 100644
> --- a/drivers/gpu/drm/meson/meson_drv.c
> +++ b/drivers/gpu/drm/meson/meson_drv.c
> @@ -11,6 +11,7 @@
>  #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>
>  
> @@ -183,6 +184,24 @@ static void meson_remove_framebuffers(void)
>  	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);
> @@ -191,7 +210,7 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
>  	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)) {
> @@ -281,6 +300,14 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
>  	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();
>  
> diff --git a/drivers/gpu/drm/meson/meson_drv.h b/drivers/gpu/drm/meson/meson_drv.h
> index 04fdf3826643..5b23704a80d6 100644
> --- a/drivers/gpu/drm/meson/meson_drv.h
> +++ b/drivers/gpu/drm/meson/meson_drv.h
> @@ -30,6 +30,10 @@ struct meson_drm_match_data {
>  	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;
> @@ -48,6 +52,8 @@ struct meson_drm {
>  	struct drm_plane *primary_plane;
>  	struct drm_plane *overlay_plane;
>  
> +	const struct meson_drm_soc_limits *limits;
> +
>  	/* Components Data */
>  	struct {
>  		bool osd1_enabled;
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index e8c94915a4fc..dc3d5122475a 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -695,6 +695,13 @@ dw_hdmi_mode_valid(struct drm_connector *connector,
>  	dev_dbg(connector->dev->dev, "%s: vclk:%d phy=%d venc=%d hdmi=%d\n",
>  		__func__, phy_freq, vclk_freq, venc_freq, hdmi_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;
> +	}
> +
>  	return meson_vclk_vic_supported_freq(phy_freq, vclk_freq);
>  }
>  
> -- 
> 2.22.0
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@xxxxxxxxxxxxxxxxxxxxx
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch