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

Sean Paul
2014-12-09T19:29:44Z

On Sun, Dec 7, 2014 at 10:40 PM, Mark Zhang <markz@nvidia.com> wrote:
> This patch adds the suspend/resume support for Tegra drm
> driver by calling the corresponding DPMS functions.
>
> Signed-off-by: Mark Zhang <markz@nvidia.com>
> ---
> 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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