Re: [PATCH] drm/tegra: dsi: Add suspend/resume support

[Sean Paul]

On Sun, Dec 7, 2014 at 10:40 PM, Mark Zhang <markz@xxxxxxxxxx> wrote:
> This patch adds the suspend/resume support for Tegra drm
> driver by calling the corresponding DPMS functions.
>
> Signed-off-by: Mark Zhang <markz@xxxxxxxxxx>
> ---
> Hi,
>
> This patch hooks DSI driver's suspend/resume to implement the whole
> display system's suspend/resume. I know this is a super ugly way,
> but as we all know, Tegra DRM driver doesn't have a dedicate drm device
> so honestly I didn't find a better way to do that.
>
> Thanks,
> Mark
>

Hi Mark,
Thanks for posting this. I've reproduced my Gerrit comments from the
CrOS tree below for the benefit of others.

>  drivers/gpu/drm/tegra/dsi.c | 96 ++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 90 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/tegra/dsi.c b/drivers/gpu/drm/tegra/dsi.c
> index 33f67fd601c6..25cd0d93f392 100644
> --- a/drivers/gpu/drm/tegra/dsi.c
> +++ b/drivers/gpu/drm/tegra/dsi.c
> @@ -61,6 +61,9 @@ struct tegra_dsi {
>         struct tegra_dsi *slave;
>  };
>
> +static int tegra_dsi_pad_calibrate(struct tegra_dsi *);
> +static int tegra_dsi_ganged_setup(struct tegra_dsi *dsi);
> +
>  static inline struct tegra_dsi *
>  host1x_client_to_dsi(struct host1x_client *client)
>  {
> @@ -805,6 +808,20 @@ static int tegra_output_dsi_setup_clock(struct tegra_output *output,
>
>         lanes = tegra_dsi_get_lanes(dsi);
>
> +       err = tegra_dsi_pad_calibrate(dsi);
> +       if (err < 0) {
> +               dev_err(dsi->dev, "MIPI calibration failed: %d\n", err);
> +               return err;
> +       }
> +       if (dsi->slave) {
> +               err = tegra_dsi_pad_calibrate(dsi->slave);
> +               if (err < 0) {
> +                       dev_err(dsi->slave->dev,
> +                               "MIPI calibration failed: %d\n", err);
> +                       return err;
> +               }
> +       }

Move this duplicate call into tegra_dsi_pad_calibrate() to be
consistent with the other functions in this file (eg:
tegra_dsi_set_timeout).

> +
>         err = tegra_dsi_get_muldiv(dsi->format, &mul, &div);
>         if (err < 0)
>                 return err;
> @@ -833,6 +850,13 @@ static int tegra_output_dsi_setup_clock(struct tegra_output *output,
>                 dev_err(dsi->dev, "failed to set parent clock: %d\n", err);
>                 return err;
>         }
> +       if (dsi->slave) {
> +               err = tegra_dsi_ganged_setup(dsi);
> +               if (err < 0) {
> +                       dev_err(dsi->dev, "DSI ganged setup failed: %d\n", err);
> +                       return err;
> +               }
> +       }

I think this belongs in ->enable() instead of here.

>
>         err = clk_set_rate(dsi->clk_parent, plld);
>         if (err < 0) {
> @@ -1470,12 +1494,6 @@ static int tegra_dsi_probe(struct platform_device *pdev)
>                 goto disable_vdd;
>         }
>
> -       err = tegra_dsi_pad_calibrate(dsi);
> -       if (err < 0) {
> -               dev_err(dsi->dev, "MIPI calibration failed: %d\n", err);
> -               goto mipi_free;
> -       }
> -
>         dsi->host.ops = &tegra_dsi_host_ops;
>         dsi->host.dev = &pdev->dev;
>
> @@ -1544,6 +1562,67 @@ static int tegra_dsi_remove(struct platform_device *pdev)
>         return 0;
>  }
>
> +#ifdef CONFIG_PM
> +static int tegra_dsi_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +       struct tegra_dsi *dsi = platform_get_drvdata(pdev);
> +       struct tegra_drm *tegra = dev_get_drvdata(dsi->client.parent);
> +       struct drm_connector *connector;
> +
> +       if (dsi->master) {
> +               regulator_disable(dsi->vdd);
> +               return 0;
> +       }
> +
> +       drm_modeset_lock_all(tegra->drm);
> +       list_for_each_entry(connector, &tegra->drm->mode_config.connector_list,
> +                           head) {
> +               int old_dpms = connector->dpms;
> +
> +               if (connector->funcs->dpms)
> +                       connector->funcs->dpms(connector, DRM_MODE_DPMS_OFF);
> +
> +               /* Set the old mode back to the connector for resume */
> +               connector->dpms = old_dpms;
> +       }
> +       drm_modeset_unlock_all(tegra->drm);
> +
> +       regulator_disable(dsi->vdd);
> +
> +       return 0;
> +}
> +
> +static int tegra_dsi_resume(struct platform_device *pdev)
> +{
> +       struct tegra_dsi *dsi = platform_get_drvdata(pdev);
> +       struct tegra_drm *tegra = dev_get_drvdata(dsi->client.parent);
> +       struct drm_connector *connector;
> +       int err = 0;
> +
> +       err = regulator_enable(dsi->vdd);
> +       if (err < 0) {
> +               dev_err(&pdev->dev, "Enable DSI vdd failed: %d\n", err);
> +               return err;
> +       }
> +
> +       if (dsi->master)
> +               return 0;
> +
> +       drm_modeset_lock_all(tegra->drm);
> +       list_for_each_entry(connector, &tegra->drm->mode_config.connector_list,
> +                           head) {
> +               if (connector->funcs->dpms)
> +                       connector->funcs->dpms(connector, connector->dpms);
> +       }
> +       drm_modeset_unlock_all(tegra->drm);
> +
> +       drm_helper_resume_force_mode(tegra->drm);
> +
> +       return 0;
> +}
> +#endif

So this is the tricky chunk, it definitely does not belong here. I
think it makes most sense for this to live in drm.c, however
host1x_driver doesn't have suspend/resume hooks.

I suspect the correct thing to do here is to add them to
host1x_driver, but I'm not sure how much effort is involved in doing
that.

Sean

> +
> +
>  static const struct of_device_id tegra_dsi_of_match[] = {
>         { .compatible = "nvidia,tegra114-dsi", },
>         { },
> @@ -1557,4 +1636,9 @@ struct platform_driver tegra_dsi_driver = {
>         },
>         .probe = tegra_dsi_probe,
>         .remove = tegra_dsi_remove,
> +#ifdef CONFIG_PM
> +       .suspend = tegra_dsi_suspend,
> +       .resume = tegra_dsi_resume,
> +#endif
> +
>  };
> --
> 1.8.1.5
>
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