On Tue, Nov 25, 2025 at 09:29:39PM +0100, David Heidelberg via B4 Relay wrote:
> From: David Heidelberg <[email protected]>
> 
> Introduce enable(), disable() and reset() functions.
> 
> The enable() and disable() callbacks keep the symmetry in the commands
> sent to the panel and also make a clearer distinction between panel
> initialization and configuration.

This also makes those to to be executed after starting the DSI stream.
Is it fine?

> 
> Splitting reset() from prepare() follows clean coding practices and lets
> us potentially make reset optional in the future for flicker-less
> takeover from a bootloader or framebuffer driver where the panel is
> already configured.
> 
> Signed-off-by: David Heidelberg <[email protected]>
> ---
>  drivers/gpu/drm/panel/panel-lg-sw43408.c | 83 
> ++++++++++++++++++++------------
>  1 file changed, 53 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panel/panel-lg-sw43408.c 
> b/drivers/gpu/drm/panel/panel-lg-sw43408.c
> index dcca7873acf8e..20217877e107f 100644
> --- a/drivers/gpu/drm/panel/panel-lg-sw43408.c
> +++ b/drivers/gpu/drm/panel/panel-lg-sw43408.c
> @@ -38,11 +38,10 @@ static inline struct sw43408_panel *to_panel_info(struct 
> drm_panel *panel)
>       return container_of(panel, struct sw43408_panel, base);
>  }
>  
> -static int sw43408_unprepare(struct drm_panel *panel)
> +static int sw43408_disable(struct drm_panel *panel)
>  {
>       struct sw43408_panel *sw43408 = to_panel_info(panel);
>       struct mipi_dsi_multi_context ctx = { .dsi = sw43408->link };
> -     int ret;
>  
>       mipi_dsi_dcs_set_display_off_multi(&ctx);
>  
> @@ -50,19 +49,55 @@ static int sw43408_unprepare(struct drm_panel *panel)
>  
>       mipi_dsi_msleep(&ctx, 100);
>  
> +     return ctx.accum_err;
> +}
> +
> +static int sw43408_unprepare(struct drm_panel *panel)
> +{
> +     struct sw43408_panel *sw43408 = to_panel_info(panel);
> +     int ret;
> +
>       gpiod_set_value(sw43408->reset_gpio, 1);
>  
>       ret = regulator_bulk_disable(ARRAY_SIZE(sw43408->supplies), 
> sw43408->supplies);
>  
> -     return ret ? : ctx.accum_err;
> +     return ret;
>  }
>  
> -static int sw43408_program(struct drm_panel *panel)
> +static int sw43408_enable(struct drm_panel *panel)

Please move it below sw43408_program() to ease code review.

>  {
>       struct sw43408_panel *sw43408 = to_panel_info(panel);
>       struct mipi_dsi_multi_context ctx = { .dsi = sw43408->link };
>       struct drm_dsc_picture_parameter_set pps;
>  
> +     mipi_dsi_dcs_set_display_on_multi(&ctx);
> +
> +     mipi_dsi_msleep(&ctx, 50);
> +
> +     sw43408->link->mode_flags &= ~MIPI_DSI_MODE_LPM;
> +
> +     drm_dsc_pps_payload_pack(&pps, sw43408->link->dsc);
> +
> +     mipi_dsi_picture_parameter_set_multi(&ctx, &pps);
> +
> +     sw43408->link->mode_flags |= MIPI_DSI_MODE_LPM;
> +
> +     /*
> +      * This panel uses PPS selectors with offset:
> +      * PPS 1 if pps_identifier is 0
> +      * PPS 2 if pps_identifier is 1
> +      */
> +     mipi_dsi_compression_mode_ext_multi(&ctx, true,
> +                                         MIPI_DSI_COMPRESSION_DSC, 1);
> +
> +     return ctx.accum_err;
> +}
> +
> +static int sw43408_program(struct drm_panel *panel)
> +{
> +     struct sw43408_panel *sw43408 = to_panel_info(panel);
> +     struct mipi_dsi_multi_context ctx = { .dsi = sw43408->link };
> +
>       mipi_dsi_dcs_write_seq_multi(&ctx, MIPI_DCS_SET_GAMMA_CURVE, 0x02);
>  
>       mipi_dsi_dcs_set_tear_on_multi(&ctx, MIPI_DSI_DCS_TEAR_MODE_VBLANK);
> @@ -97,26 +132,19 @@ static int sw43408_program(struct drm_panel *panel)
>       mipi_dsi_dcs_write_seq_multi(&ctx, 0x55, 0x04, 0x61, 0xdb, 0x04, 0x70, 
> 0xdb);
>       mipi_dsi_dcs_write_seq_multi(&ctx, 0xb0, 0xca);
>  
> -     mipi_dsi_dcs_set_display_on_multi(&ctx);
> -
> -     mipi_dsi_msleep(&ctx, 50);
> -
> -     sw43408->link->mode_flags &= ~MIPI_DSI_MODE_LPM;
> -
> -     drm_dsc_pps_payload_pack(&pps, sw43408->link->dsc);
> -
> -     mipi_dsi_picture_parameter_set_multi(&ctx, &pps);
> +     return ctx.accum_err;
> +}
>  
> -     sw43408->link->mode_flags |= MIPI_DSI_MODE_LPM;
> +static void sw43408_reset(struct sw43408_panel *ctx)
> +{
> +     usleep_range(5000, 6000);
>  
> -     /*
> -      * This panel uses PPS selectors with offset:
> -      * PPS 1 if pps_identifier is 0
> -      * PPS 2 if pps_identifier is 1
> -      */
> -     mipi_dsi_compression_mode_ext_multi(&ctx, true,
> -                                         MIPI_DSI_COMPRESSION_DSC, 1);
> -     return ctx.accum_err;
> +     gpiod_set_value(ctx->reset_gpio, 0);
> +     usleep_range(9000, 10000);
> +     gpiod_set_value(ctx->reset_gpio, 1);
> +     usleep_range(1000, 2000);
> +     gpiod_set_value(ctx->reset_gpio, 0);
> +     usleep_range(9000, 10000);
>  }
>  
>  static int sw43408_prepare(struct drm_panel *panel)
> @@ -128,14 +156,7 @@ static int sw43408_prepare(struct drm_panel *panel)
>       if (ret < 0)
>               return ret;
>  
> -     usleep_range(5000, 6000);
> -
> -     gpiod_set_value(ctx->reset_gpio, 0);
> -     usleep_range(9000, 10000);
> -     gpiod_set_value(ctx->reset_gpio, 1);
> -     usleep_range(1000, 2000);
> -     gpiod_set_value(ctx->reset_gpio, 0);
> -     usleep_range(9000, 10000);
> +     sw43408_reset(ctx);
>  
>       ret = sw43408_program(panel);
>       if (ret)
> @@ -208,6 +229,8 @@ static int sw43408_backlight_init(struct sw43408_panel 
> *ctx)
>  }
>  
>  static const struct drm_panel_funcs sw43408_funcs = {
> +     .disable = sw43408_disable,
> +     .enable = sw43408_enable,
>       .unprepare = sw43408_unprepare,
>       .prepare = sw43408_prepare,
>       .get_modes = sw43408_get_modes,
> 
> -- 
> 2.51.0
> 
> 

-- 
With best wishes
Dmitry

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