Hi,

2018-02-08 18:48 GMT+01:00 Sean Paul <seanp...@chromium.org>:
> This patch adds the ability to override the typical display timing for a
> given panel. This is useful for devices which have timing constraints
> that do not apply across the entire display driver (eg: to avoid
> crosstalk between panel and digitizer on certain laptops). The rules are
> as follows:
>
> - panel must not specify fixed mode (since the override mode will
>   either be the same as the fixed mode, or we'll be unable to
>   check the bounds of the overried)
> - panel must specify at least one display_timing range which will be
>   used to ensure the override mode fits within its bounds
>
> Changes in v2:
>  - Parse the full display-timings node (using the native-mode) (Rob)
> Changes in v3:
>  - No longer parse display-timings subnode, use panel-timing (Rob)
>
> Cc: Doug Anderson <diand...@chromium.org>
> Cc: Eric Anholt <e...@anholt.net>
> Cc: Heiko Stuebner <he...@sntech.de>
> Cc: Jeffy Chen <jeffy.c...@rock-chips.com>
> Cc: Rob Herring <robh...@kernel.org>
> Cc: St├ęphane Marchesin <marc...@chromium.org>
> Cc: Thierry Reding <thierry.red...@gmail.com>
> Cc: devicet...@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Signed-off-by: Sean Paul <seanp...@chromium.org>
> ---
>  drivers/gpu/drm/panel/panel-simple.c | 67 
> +++++++++++++++++++++++++++++++++++-
>  1 file changed, 66 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/panel/panel-simple.c 
> b/drivers/gpu/drm/panel/panel-simple.c
> index 5591984a392b..87488392bca1 100644
> --- a/drivers/gpu/drm/panel/panel-simple.c
> +++ b/drivers/gpu/drm/panel/panel-simple.c
> @@ -34,6 +34,7 @@
>  #include <drm/drm_panel.h>
>
>  #include <video/display_timing.h>
> +#include <video/of_display_timing.h>
>  #include <video/videomode.h>
>
>  struct panel_desc {
> @@ -87,6 +88,8 @@ struct panel_simple {
>         struct i2c_adapter *ddc;
>
>         struct gpio_desc *enable_gpio;
> +
> +       struct drm_display_mode override_mode;
>  };
>
>  static inline struct panel_simple *to_panel_simple(struct drm_panel *panel)
> @@ -99,11 +102,22 @@ static int panel_simple_get_fixed_modes(struct 
> panel_simple *panel)
>         struct drm_connector *connector = panel->base.connector;
>         struct drm_device *drm = panel->base.drm;
>         struct drm_display_mode *mode;
> +       bool has_override = panel->override_mode.type;
>         unsigned int i, num = 0;
>
>         if (!panel->desc)
>                 return 0;
>
> +       if (has_override) {
> +               mode = drm_mode_duplicate(drm, &panel->override_mode);
> +               if (mode) {
> +                       drm_mode_probed_add(connector, mode);
> +                       num++;
> +               } else {
> +                       dev_err(drm->dev, "failed to add override mode\n");
> +               }
> +       }
> +
>         for (i = 0; i < panel->desc->num_timings; i++) {
>                 const struct display_timing *dt = &panel->desc->timings[i];
>                 struct videomode vm;
> @@ -120,7 +134,7 @@ static int panel_simple_get_fixed_modes(struct 
> panel_simple *panel)
>
>                 mode->type |= DRM_MODE_TYPE_DRIVER;
>
> -               if (panel->desc->num_timings == 1)
> +               if (panel->desc->num_timings == 1 && !has_override)
>                         mode->type |= DRM_MODE_TYPE_PREFERRED;
>
>                 drm_mode_probed_add(connector, mode);
> @@ -291,10 +305,58 @@ static const struct drm_panel_funcs panel_simple_funcs 
> = {
>         .get_timings = panel_simple_get_timings,
>  };
>
> +#define PANEL_SIMPLE_BOUNDS_CHECK(to_check, bounds, field) \
> +       (to_check->field.typ >= bounds->field.min && \
> +        to_check->field.typ <= bounds->field.max)
> +static void panel_simple_add_override_mode(struct device *dev,
> +                                          struct panel_simple *panel,
> +                                          const struct display_timing *ot)
> +{
> +       const struct panel_desc *desc = panel->desc;
> +       struct videomode vm;
> +       int i;
> +
> +       if (desc->num_modes) {
> +               dev_err(dev, "Reject override mode: panel has a fixed 
> mode\n");
> +               return;
> +       }
> +       if (!desc->num_timings) {
> +               dev_err(dev, "Reject override mode: no timings specified\n");
> +               return;
> +       }
> +
> +       for (i = 0; i < panel->desc->num_timings; i++) {
> +               const struct display_timing *dt = &panel->desc->timings[i];
> +
> +               if (!PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hactive) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hfront_porch) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hback_porch) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, hsync_len) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vactive) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vfront_porch) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vback_porch) ||
> +                   !PANEL_SIMPLE_BOUNDS_CHECK(ot, dt, vsync_len))
> +                       continue;
> +
> +               if (ot->flags != dt->flags)
> +                       continue;
> +
> +               videomode_from_timing(ot, &vm);
> +               drm_display_mode_from_videomode(&vm, &panel->override_mode);
> +               panel->override_mode.type |= DRM_MODE_TYPE_DRIVER |
> +                                            DRM_MODE_TYPE_PREFERRED;
> +               return;
> +       }
> +
> +       dev_err(dev, "Reject override mode: No display_timing found\n");
> +       return;
> +}
> +
>  static int panel_simple_probe(struct device *dev, const struct panel_desc 
> *desc)
>  {
>         struct device_node *backlight, *ddc;
>         struct panel_simple *panel;
> +       struct display_timing dt;
>         int err;
>
>         panel = devm_kzalloc(dev, sizeof(*panel), GFP_KERNEL);
> @@ -338,6 +400,9 @@ static int panel_simple_probe(struct device *dev, const 
> struct panel_desc *desc)
>                 }
>         }
>
> +       if (!of_get_display_timing(dev->of_node, "panel-timing", &dt))
> +               panel_simple_add_override_mode(dev, panel, &dt);
> +
>         drm_panel_init(&panel->base);
>         panel->base.dev = dev;
>         panel->base.funcs = &panel_simple_funcs;
> --

Tested on top of linux-next on a Samsung Chromebook Plus.

Tested-by: Enric Balletbo i Serra <enric.balle...@collabora.com>



> 2.16.0.rc1.238.g530d649a79-goog
>
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