linux-kernel - Re: [PATCH RFC 5/7] drm/panel: novatek-nt36672e: use wrapped MIPI DCS functions

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Date: Fri, 10 May 2024 14:46:48 -0700
From: Doug Anderson <dianders@...omium.org>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Jessica Zhang <quic_jesszhan@...cinc.com>, 
	Sam Ravnborg <sam@...nborg.org>, Sumit Semwal <sumit.semwal@...aro.org>, 
	Caleb Connolly <caleb.connolly@...aro.org>, Marijn Suijten <marijn.suijten@...ainline.org>, 
	Vinod Koul <vkoul@...nel.org>, dri-devel@...ts.freedesktop.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC 5/7] drm/panel: novatek-nt36672e: use wrapped MIPI DCS functions

Hi,

On Thu, May 9, 2024 at 3:37 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> Remove conditional code and always use mipi_dsi_dcs_*multi() wrappers to
> simplify driver's init/exit code. This also includes passing context to
> the init_sequence() function instead of passing the DSI device.
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>  drivers/gpu/drm/panel/panel-novatek-nt36672e.c | 587 ++++++++++++-------------
>  1 file changed, 281 insertions(+), 306 deletions(-)

One note is that we might not be able to land ${SUBJECT} patch since
the patch it's based on [1] doesn't have any Reviewed-by tags. Just
sayin'. ;-)

[1] https://lore.kernel.org/r/20240508135148.v4.6.I3c08a7d02c467d2bc88da14e513ea4c8649fce45@changeid


> @@ -381,61 +377,40 @@ static int nt36672e_power_off(struct nt36672e_panel *ctx)
>         return ret;
>  }
>
> -static int nt36672e_on(struct nt36672e_panel *ctx)
> +static int nt36672e_on(struct nt36672e_panel *panel)

Small nit that I think of the variable "panel" as referring to a
"struct drm_panel". I'd personally rather this be named something
else, like "nt36672e".


>  {
> -       struct mipi_dsi_device *dsi = ctx->dsi;
> -       const struct panel_desc *desc = ctx->desc;
> -       int ret = 0;
> +       struct mipi_dsi_multi_context ctx = { .dsi = panel->dsi };
> +       struct mipi_dsi_device *dsi = panel->dsi;
> +       const struct panel_desc *desc = panel->desc;
>
>         dsi->mode_flags |= MIPI_DSI_MODE_LPM;
>
> -       if (desc->init_sequence) {
> -               ret = desc->init_sequence(dsi);
> -               if (ret < 0) {
> -                       dev_err(&dsi->dev, "panel init sequence failed: %d\n", ret);
> -                       return ret;
> -               }
> -       }
> +       if (desc->init_sequence)
> +               desc->init_sequence(&ctx);
>
> -       ret = mipi_dsi_dcs_exit_sleep_mode(dsi);
> -       if (ret < 0) {
> -               dev_err(&dsi->dev, "Failed to exit sleep mode: %d\n", ret);
> -               return ret;
> -       }
> -       msleep(120);
> +       mipi_dsi_dcs_exit_sleep_mode_multi(&ctx);
> +       mipi_dsi_msleep(&ctx, 120);
>
> -       ret = mipi_dsi_dcs_set_display_on(dsi);
> -       if (ret < 0) {
> -               dev_err(&dsi->dev, "Failed to set display on: %d\n", ret);
> -               return ret;
> -       }
> -       msleep(100);
> +       mipi_dsi_dcs_set_display_on_multi(&ctx);
>
> -       return 0;
> +       mipi_dsi_msleep(&ctx, 100);
> +
> +       return ctx.accum_err;
>  }
>
> -static int nt36672e_off(struct nt36672e_panel *ctx)
> +static int nt36672e_off(struct nt36672e_panel *panel)
>  {
> -       struct mipi_dsi_device *dsi = ctx->dsi;
> -       int ret = 0;
> +       struct mipi_dsi_multi_context ctx = { .dsi = panel->dsi };
>
> -       dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
> +       panel->dsi->mode_flags &= ~MIPI_DSI_MODE_LPM;
>
> -       ret = mipi_dsi_dcs_set_display_off(dsi);
> -       if (ret < 0) {
> -               dev_err(&dsi->dev, "Failed to set display off: %d\n", ret);
> -               return ret;
> -       }
> -       msleep(20);
> +       mipi_dsi_dcs_set_display_off_multi(&ctx);
> +       mipi_dsi_msleep(&ctx, 20);
>
> -       ret = mipi_dsi_dcs_enter_sleep_mode(dsi);
> -       if (ret < 0) {
> -               dev_err(&dsi->dev, "Failed to enter sleep mode: %d\n", ret);
> -               return ret;
> -       }
> -       msleep(60);
> +       mipi_dsi_dcs_enter_sleep_mode_multi(&ctx);
> +       mipi_dsi_msleep(&ctx, 60);
>
> -       return 0;
> +       return ctx.accum_err;
>  }

nit: similar to other patches in the series, the callers of
nt36672e_on() and nt36672e_off() should be able to get rid of their
error prints.

In any case:

Reviewed-by: Douglas Anderson <dianders@...omium.org>