On Tue, Dec 17, 2024 at 03:32:15PM +0100, Herve Codina wrote:
> In some cases observed during ESD tests, the TI SN65DSI83 cannot recover
> from errors by itself. A full restart of the bridge is needed in those
> cases to have the bridge output LVDS signals again.
>
> Also, during tests, cases were observed where reading the status of the
> bridge was not even possible. Indeed, in those cases, the bridge stops
> to acknowledge I2C transactions. Only a full reset of the bridge (power
> off/on) brings back the bridge to a functional state.
>
> The TI SN65DSI83 has some error detection capabilities. Introduce an
> error recovery mechanism based on this detection.
>
> The errors detected are signaled through an interrupt. On system where
> this interrupt is not available, the driver uses a polling monitoring
> fallback to check for errors. When an error is present or when reading
> the bridge status leads to an I2C failure, the recovery process is
> launched.
>
> Restarting the bridge needs to redo the initialization sequence. This
> initialization sequence has to be done with the DSI data lanes driven in
> LP11 state. In order to do that, the recovery process resets the whole
> output path (i.e the path from the encoder to the connector) where the
> bridge is located.
>
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> ---
> drivers/gpu/drm/bridge/ti-sn65dsi83.c | 142 ++++++++++++++++++++++++++
> 1 file changed, 142 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/ti-sn65dsi83.c b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> index e6264514bb3f..f3d66d17f28c 100644
> --- a/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> +++ b/drivers/gpu/drm/bridge/ti-sn65dsi83.c
> @@ -35,9 +35,12 @@
> #include <linux/of_graph.h>
> #include <linux/regmap.h>
> #include <linux/regulator/consumer.h>
> +#include <linux/timer.h>
> +#include <linux/workqueue.h>
>
> #include <drm/drm_atomic_helper.h>
> #include <drm/drm_bridge.h>
> +#include <drm/drm_drv.h> /* DRM_MODESET_LOCK_ALL_BEGIN() need drm_drv_uses_atomic_modeset() */
> #include <drm/drm_mipi_dsi.h>
> #include <drm/drm_of.h>
> #include <drm/drm_panel.h>
> @@ -147,6 +150,9 @@ struct sn65dsi83 {
> struct regulator *vcc;
> bool lvds_dual_link;
> bool lvds_dual_link_even_odd_swap;
> + bool use_irq;
> + struct delayed_work monitor_work;
> + struct work_struct reset_work;
> };
>
> static const struct regmap_range sn65dsi83_readable_ranges[] = {
> @@ -328,6 +334,106 @@ static u8 sn65dsi83_get_dsi_div(struct sn65dsi83 *ctx)
> return dsi_div - 1;
> }
>
> +static int sn65dsi83_reset_drm_output(struct sn65dsi83 *sn65dsi83)
> +{
> + struct drm_atomic_state *state = ERR_PTR(-EINVAL);
> + struct drm_device *dev = sn65dsi83->bridge.dev;
> + struct drm_modeset_acquire_ctx ctx;
> + struct drm_connector *connector;
> + int err;
> +
> + /*
> + * Reset components available from the encoder to the connector.
> + * To do that, we disable then re-enable the connector linked to the
> + * encoder.
> + *
> + * This way, drm core will reconfigure each components. In our case,
> + * this will force the previous component to go back in LP11 mode and
> + * so allow the reconfiguration of SN64DSI83 bridge.
> + *
> + * Keep the lock during the whole operation to be atomic.
> + */
> +
> + DRM_MODESET_LOCK_ALL_BEGIN(dev, ctx, 0, err);
> +
> + state = drm_atomic_helper_duplicate_state(dev, &ctx);
> + if (IS_ERR(state)) {
> + err = PTR_ERR(state);
> + goto unlock;
> + }
> +
> + connector = drm_atomic_get_old_connector_for_encoder(state,
> + sn65dsi83->bridge.encoder);
> + if (!connector) {
> + err = -EINVAL;
> + goto unlock;
> + }
> +
> + err = drm_atomic_helper_disable_connector(connector, &ctx);
> + if (err < 0)
> + goto unlock;
> +
> + /* Restore original state to re-enable the connector */
> + err = drm_atomic_helper_commit_duplicated_state(state, &ctx);
> +
> +unlock:
> + DRM_MODESET_LOCK_ALL_END(dev, ctx, err);
> + if (!IS_ERR(state))
> + drm_atomic_state_put(state);
> + return err;
> +}
In the previous version, we advised to create a generic helper similar
to vc4 and i915 reset_pipe() and and intel_modeset_commit_pipes().
It looks like you chose a different path. Can you expand why?
Maxime
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