On Tue, Mar 04, 2025 at 12:10:57PM +0100, Maxime Ripard wrote:
> The tc358768 bridge driver, if enabling it fails, tries to disable it.
> This is pretty uncommon in bridge drivers, and also stands in the way
> for further reworks.
>
> Worse, since pre_enable and enable aren't expected to fail, disable and
> post_disable might be called twice: once to handle the failure, and once
> to actually disable the bridge.
>
> Since post_disable uses regulators and clocks, this would lead to enable
> count imbalances.
>
> In order to prevent that imbalance, and to allow further reworks, let's
> drop the calls to disable and post_disable, but keep the warning to let
> users know about what's going on.
>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> Signed-off-by: Maxime Ripard <mripard@kernel.org>
Yeah proper way to clear these would be like any other link failure:
- Launch async worker to do a bridge reset with the fancy new helper.
- Set the link-status attribute if you can't automatically fix it and let
userspace sort out the mess.
Maybe we need to improve the docs a bit more?
-Sima
> ---
> drivers/gpu/drm/bridge/tc358768.c | 10 ++--------
> 1 file changed, 2 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c
> index 6db18d1e8824dd7d387211d6d1e668645cf88bbe..6b65ba8aed86012bc0f464bd5ee44325dae677c6 100644
> --- a/drivers/gpu/drm/bridge/tc358768.c
> +++ b/drivers/gpu/drm/bridge/tc358768.c
> @@ -1075,15 +1075,12 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge)
> val = TC358768_DSI_CONFW_MODE_CLR | TC358768_DSI_CONFW_ADDR_DSI_CONTROL;
> val |= TC358768_DSI_CONTROL_DIS_MODE; /* DSI mode */
> tc358768_write(priv, TC358768_DSI_CONFW, val);
>
> ret = tc358768_clear_error(priv);
> - if (ret) {
> + if (ret)
> dev_err(dev, "Bridge pre_enable failed: %d\n", ret);
> - tc358768_bridge_disable(bridge);
> - tc358768_bridge_post_disable(bridge);
> - }
> }
>
> static void tc358768_bridge_enable(struct drm_bridge *bridge)
> {
> struct tc358768_priv *priv = bridge_to_tc358768(bridge);
> @@ -1099,15 +1096,12 @@ static void tc358768_bridge_enable(struct drm_bridge *bridge)
>
> /* set PP_en */
> tc358768_update_bits(priv, TC358768_CONFCTL, BIT(6), BIT(6));
>
> ret = tc358768_clear_error(priv);
> - if (ret) {
> + if (ret)
> dev_err(priv->dev, "Bridge enable failed: %d\n", ret);
> - tc358768_bridge_disable(bridge);
> - tc358768_bridge_post_disable(bridge);
> - }
> }
>
> #define MAX_INPUT_SEL_FORMATS 1
>
> static u32 *
>
> --
> 2.48.1
>
--
Simona Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch