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SubjectRe: [PATCH 1/2] drm: bridge: dw-hdmi: Add hooks for suspend/resume
Hi Douglas,

Thank you for the patch.

On Thu, May 02, 2019 at 03:38:07PM -0700, Douglas Anderson wrote:
> On Rockchip rk3288-based Chromebooks when you do a suspend/resume
> cycle:
>
> 1. You lose the ability to detect an HDMI device being plugged in.
>
> 2. If you're using the i2c bus built in to dw_hdmi then it stops
> working.
>
> Let's add a hook to the core dw-hdmi driver so that we can call it in
> dw_hdmi-rockchip in the next commit.
>
> NOTE: the exact set of steps I've done here in resume come from
> looking at the normal dw_hdmi init sequence in upstream Linux plus the
> sequence that we did in downstream Chrome OS 3.14. Testing show that
> it seems to work, but if an extra step is needed or something here is
> not needed we could improve it.
>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
>
> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 21 +++++++++++++++++++++
> include/drm/bridge/dw_hdmi.h | 3 +++
> 2 files changed, 24 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index db761329a1e3..4b38bfd43e59 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -2780,6 +2780,27 @@ void dw_hdmi_unbind(struct dw_hdmi *hdmi)
> }
> EXPORT_SYMBOL_GPL(dw_hdmi_unbind);
>
> +int dw_hdmi_suspend(struct dw_hdmi *hdmi)
> +{
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(dw_hdmi_suspend);
> +

As this is empty, should we leave it out ? It adds a bit of bloat to the
kernel for no real reason, and we can add it later if required.

> +int dw_hdmi_resume(struct dw_hdmi *hdmi)
> +{
> + initialize_hdmi_ih_mutes(hdmi);
> +
> + dw_hdmi_setup_i2c(hdmi);
> + if (hdmi->i2c)
> + dw_hdmi_i2c_init(hdmi);
> +
> + if (hdmi->phy.ops->setup_hpd)
> + hdmi->phy.ops->setup_hpd(hdmi, hdmi->phy.data);
> +
> + return 0;

How about refactoring the probe function to extract hardware
initialisation to a separate function, and calling it from here ?

> +}
> +EXPORT_SYMBOL_GPL(dw_hdmi_resume);
> +
> MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
> MODULE_AUTHOR("Andy Yan <andy.yan@rock-chips.com>");
> MODULE_AUTHOR("Yakir Yang <ykk@rock-chips.com>");
> diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
> index 66e70770cce5..c4132e9a5ae3 100644
> --- a/include/drm/bridge/dw_hdmi.h
> +++ b/include/drm/bridge/dw_hdmi.h
> @@ -154,6 +154,9 @@ struct dw_hdmi *dw_hdmi_bind(struct platform_device *pdev,
> struct drm_encoder *encoder,
> const struct dw_hdmi_plat_data *plat_data);
>
> +int dw_hdmi_suspend(struct dw_hdmi *hdmi);
> +int dw_hdmi_resume(struct dw_hdmi *hdmi);
> +
> void dw_hdmi_setup_rx_sense(struct dw_hdmi *hdmi, bool hpd, bool rx_sense);
>
> void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate);

--
Regards,

Laurent Pinchart

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