Currently, the irq handler that monitores changes for HPD anx RX_SENSE relies on the status of the bridge for updating the status of the HPD. The update is done only when the bridge is enabled.
However, on Rockchip platforms we have found use cases where it could be a problem. When HDMI is being used, turning off/on the screen or unplugging/re-plugging the cable, the following simplified code path will happen:
- dw_hdmi_irq() will be triggered by an HPD event, as the bridge is on hdmi->disabled is false, then the handler will update the rxsense flag accordingly. - dw_hdmi_update_power() will be invoked with the mode DRM_FORCE_UNSPECIFIED and rxsense == 1, so dw_hdmi_poweroff() will be called and the PHY will be desactivated (its pixel clocks and TMDS)
[...]
- dw_hdmi_bridge_disable() will be invoked, the bridge will be marked as disabled.
- dw_hdmi_irq() will be triggered by an HPD event, as the bridge is currently disabled the HPD status won't be updated, so hdmi->rxsense won't be changed. Even if the data part of the PHY is disabled, this information coming from the HDMI Transmitter is correct and should be saved.
[...]
- dw_hdmi_bridge_enable() will be invoked, the bridge will be marked as enabled. - dw_hdmi_update_power() will be called. When hdmi->force is equal to DRM_FORCE_UNSPECIFIED the function will rely on hdmi->rxsense. If this field has not been updated by the irq handler, it will be false and DRM_FORCE_ON won't be put to hdmi->force.
Consequently, most of the time dw_hdmi_poweron() won't be called in this use case, TMDS won't be re-enabled the PHY won't be re-initialized, resulting in a "Signal not found".
This commit fixes the issue by removing the check for "!hdmi->disabled". As already explained, even if the PHY is partially disabled, information coming from HDMI Transmitter about HPD should be saved for a later use.
Signed-off-by: Romain Perier romain.perier@collabora.com ---
Changes in v2: - I have re-worded the commit message, as suggested by Russel
drivers/gpu/drm/bridge/dw-hdmi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/bridge/dw-hdmi.c b/drivers/gpu/drm/bridge/dw-hdmi.c index 3a70016..5b6090c 100644 --- a/drivers/gpu/drm/bridge/dw-hdmi.c +++ b/drivers/gpu/drm/bridge/dw-hdmi.c @@ -1793,7 +1793,7 @@ static irqreturn_t dw_hdmi_irq(int irq, void *dev_id) if (intr_stat & (HDMI_IH_PHY_STAT0_RX_SENSE | HDMI_IH_PHY_STAT0_HPD)) { mutex_lock(&hdmi->mutex); - if (!hdmi->disabled && !hdmi->force) { + if (!hdmi->force) { /* * If the RX sense status indicates we're disconnected, * clear the software rxsense status.