mirror of https://gitee.com/openkylin/linux.git
187697a454
Currently, the irq handler that monitors changes for HPD and 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> Signed-off-by: Archit Taneja <architt@codeaurora.org> Link: https://patchwork.freedesktop.org/patch/143602/ |
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.