Re: [PATCH v2 03/13] drm/sun4i: tcon: Add support for demuxing TCON output on A31

From: Maxime Ripard
Date: Tue Sep 26 2017 - 05:56:11 EST


Hi,

On Tue, Sep 26, 2017 at 06:59:09AM +0000, Chen-Yu Tsai wrote:
> On systems with 2 TCONs such as the A31, it is possible to demux the
> output of the TCONs to one encoder.
>
> Add support for this for the A31.
>
> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> ---
> drivers/gpu/drm/sun4i/sun4i_tcon.c | 61 ++++++++++++++++++++++++++++++++++++++
> 1 file changed, 61 insertions(+)
>
> diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> index e853dfe51389..770b843a6fa9 100644
> --- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
> +++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
> @@ -14,9 +14,12 @@
> #include <drm/drm_atomic_helper.h>
> #include <drm/drm_crtc.h>
> #include <drm/drm_crtc_helper.h>
> +#include <drm/drm_encoder.h>
> #include <drm/drm_modes.h>
> #include <drm/drm_of.h>
>
> +#include <uapi/drm/drm_mode.h>
> +
> #include <linux/component.h>
> #include <linux/ioport.h>
> #include <linux/of_address.h>
> @@ -109,11 +112,69 @@ void sun4i_tcon_enable_vblank(struct sun4i_tcon *tcon, bool enable)
> }
> EXPORT_SYMBOL(sun4i_tcon_enable_vblank);
>
> +static struct sun4i_tcon *sun4i_get_first_tcon(struct drm_device *drm)
> +{
> + struct sun4i_drv *drv = drm->dev_private;
> + struct sun4i_tcon *tcon;
> +
> + list_for_each_entry(tcon, &drv->tcon_list, list)
> + if (tcon->id == 0)
> + return tcon;
> +
> + dev_warn(drm->dev,
> + "TCON0 not found, display output muxing may not work\n");
> +
> + return tcon;
> +}
> +
> +static int _sun6i_tcon_set_mux(struct drm_encoder *encoder)
> +{
> + struct sun4i_tcon *tcon = sun4i_get_first_tcon(encoder->dev);
> + int tcon_id = drm_crtc_to_sun4i_crtc(encoder->crtc)->tcon->id;
> + u32 shift;
> +
> + DRM_DEBUG_DRIVER("Muxing encoder %s to CRTC %s (TCON %d)\n",
> + encoder->name, encoder->crtc->name, tcon_id);
> +
> + /* Only 2 TCONs */
> + if (tcon_id >= 2)
> + return -EINVAL;
> +
> + switch (encoder->encoder_type) {
> + case DRM_MODE_ENCODER_TMDS:
> + /* HDMI */
> + shift = 8;
> + break;
> + case DRM_MODE_ENCODER_DSI:
> + /* No MIPI DSI on A31s */
> + if (of_device_is_compatible(tcon->dev->of_node,
> + "allwinner,sun6i-a31s-tcon"))

I'm not sure that test is needed.

We won't end up in that case if we don't have a connected DSI block,
which isn't going to be the case on the A31. And I guess we can tackle
DSI later (when I'll send my patches...).

> + return -EINVAL;
> + shift = 0;
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + regmap_update_bits(tcon->regs, SUN4I_TCON_MUX_CTRL_REG,
> + 0x3 << shift, tcon_id << shift);
> +
> + return 0;
> +}
> +
> void sun4i_tcon_set_mux(struct sun4i_tcon *tcon, int channel,
> struct drm_encoder *encoder)
> {
> + /* Get the device node of the display engine */
> + struct device_node *node = encoder->dev->dev->of_node;
> u32 val;
>
> + if (of_device_is_compatible(node, "allwinner,sun6i-a31-display-engine") ||
> + of_device_is_compatible(node, "allwinner,sun6i-a31s-display-engine")) {
> + _sun6i_tcon_set_mux(encoder);
> + return;
> + }
> +

I'd really like to avoid mix and matching the structure defined
behaviour and those of_device_is_compatible calls spread out
everywhere.

You can either add a flag or a function pointer.

Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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