2020-11-16 21:57:28

by Marc Zyngier

Subject: [PATCH 4/4] drm/meson: dw-hdmi: Ensure that clocks are enabled before touching the TOP registers

Removing the meson-dw-hdmi module and re-inserting it results in a hang
as the driver writes to HDMITX_TOP_SW_RESET. Similar effects can be seen
when booting with mainline u-boot and using the u-boot provided DT (which
is highly desirable).

The reason for the hang seem to be that the clocks are not always
enabled by the time we enter meson_dw_hdmi_init(). Moving this call
*after* dw_hdmi_probe() ensures that the clocks are enabled.

Signed-off-by: Marc Zyngier <[email protected]>
---
drivers/gpu/drm/meson/meson_dw_hdmi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
index 68826cf9993f..7f8eea494147 100644
--- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
+++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
@@ -1073,8 +1073,6 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,

DRM_DEBUG_DRIVER("encoder initialized\n");

- meson_dw_hdmi_init(meson_dw_hdmi);
-
/* Bridge / Connector */

dw_plat_data->priv_data = meson_dw_hdmi;
@@ -1097,6 +1095,8 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
if (IS_ERR(meson_dw_hdmi->hdmi))
return PTR_ERR(meson_dw_hdmi->hdmi);

+ meson_dw_hdmi_init(meson_dw_hdmi);
+
next_bridge = of_drm_find_bridge(pdev->dev.of_node);
if (next_bridge)
drm_bridge_attach(encoder, next_bridge,
--
2.28.0

2020-11-17 09:00:26

by Neil Armstrong

Subject: Re: [PATCH 4/4] drm/meson: dw-hdmi: Ensure that clocks are enabled before touching the TOP registers

On 16/11/2020 21:07, Marc Zyngier wrote:
> Removing the meson-dw-hdmi module and re-inserting it results in a hang
> as the driver writes to HDMITX_TOP_SW_RESET. Similar effects can be seen
> when booting with mainline u-boot and using the u-boot provided DT (which
> is highly desirable).
>
> The reason for the hang seem to be that the clocks are not always
> enabled by the time we enter meson_dw_hdmi_init(). Moving this call
> *after* dw_hdmi_probe() ensures that the clocks are enabled.
>
> Signed-off-by: Marc Zyngier <[email protected]>

Fixes: 1374b8375c2e ("drm/meson: dw_hdmi: add resume/suspend hooks")

> ---
> drivers/gpu/drm/meson/meson_dw_hdmi.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/meson/meson_dw_hdmi.c b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> index 68826cf9993f..7f8eea494147 100644
> --- a/drivers/gpu/drm/meson/meson_dw_hdmi.c
> +++ b/drivers/gpu/drm/meson/meson_dw_hdmi.c
> @@ -1073,8 +1073,6 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
>
> DRM_DEBUG_DRIVER("encoder initialized\n");
>
> - meson_dw_hdmi_init(meson_dw_hdmi);
> -
> /* Bridge / Connector */
>
> dw_plat_data->priv_data = meson_dw_hdmi;
> @@ -1097,6 +1095,8 @@ static int meson_dw_hdmi_bind(struct device *dev, struct device *master,
> if (IS_ERR(meson_dw_hdmi->hdmi))
> return PTR_ERR(meson_dw_hdmi->hdmi);
>
> + meson_dw_hdmi_init(meson_dw_hdmi);
> +
> next_bridge = of_drm_find_bridge(pdev->dev.of_node);
> if (next_bridge)
> drm_bridge_attach(encoder, next_bridge,
>

Acked-by: Neil Armstrong <[email protected]>