Re: [PATCH -v2] drm/exynos: do not disable hdmi clocks for exynos5420

[Joonyoung Shim <jy0922.shim@samsung.com>]

Hi,

On 02/02/2015 11:26 PM, Gustavo Padovan wrote:
> From: Prathyush K <prathyush.k@samsung.com>
> 
> When VPLL clock of less than 140 MHz was used and all the three clocks -
> hdmiphy, hdmi, sclk_hdmi are disabled, the system hangs during S2R when
> HDMI is connected. Since we want to use a vpll clock of 70.5 MHz, we
> cannot disable these 3 clocks before suspending.  This patch add an extra
> clk enable/disable of hdmi and sclk_hdmi outside of the pm ops so these
> clocks are always enabled. Now system suspends and resumes with HDMI
> connected with VPLL set at 70.5 MHz.
> 
> This is not the best solution, but it inhibits a crash while we figure out
> what is the correct solution for this issue.
> 
> Signed-off-by: Prathyush K <prathyush.k@samsung.com>
> Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
> Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
> ---
>  drivers/gpu/drm/exynos/exynos_hdmi.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
> index 6aa0d65..c6baf64 100644
> --- a/drivers/gpu/drm/exynos/exynos_hdmi.c
> +++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
> @@ -2254,6 +2254,20 @@ static int hdmi_resources_init(struct hdmi_context *hdata)
>  	} else
>  		res->reg_hdmi_en = NULL;
>  
> +	/*
> +	 * For these two clocks exynos5420 fails to suspend if VPLL clock of
> +	 * 70.5 MHz is used and these clocks are disabled before suspend. So
> +	 * enable them here.
> +	 * Note that this will keep the clocks enabled for the entire
> +	 * lifetime of the driver and waste energy when it is suspended.
> +	 * However it prevents the system crash until a better solution is
> +	 * found
> +	 */
> +	if (of_device_is_compatible(dev->of_node, "samsung,exynos5420-hdmi")) {
> +		clk_prepare_enable(res->sclk_hdmi);
> +		clk_prepare_enable(res->hdmi);
> +	}
> +
>  	return ret;
>  fail:
>  	DRM_ERROR("HDMI resource init - failed\n");
> @@ -2516,6 +2530,12 @@ static int hdmi_remove(struct platform_device *pdev)
>  	if (hdata->res.reg_hdmi_en)
>  		regulator_disable(hdata->res.reg_hdmi_en);
>  
> +	if (of_device_is_compatible(hdata->dev->of_node,
> +				    "samsung,exynos5420-hdmi")) {
> +		clk_disable_unprepare(hdata->res.sclk_hdmi);
> +		clk_disable_unprepare(hdata->res.hdmi);
> +	}
> +
>  	if (hdata->hdmiphy_port)
>  		put_device(&hdata->hdmiphy_port->dev);
>  	put_device(&hdata->ddc_adpt->dev);
> 

Looks fine to me but i'm not sure any there are any side effects to
change parent clock of mout_hdmi clock.

Acked-by: Joonyoung Shim <jy0922.shim@samsung.com>

Thanks.
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