Il 12/11/21 11:54, Yong Wu ha scritto:
MediaTek IOMMU-SMI diagram is like below. all the consumer connect with smi-larb, then connect with smi-common.
M4U | smi-common |
| | ... | | larb1 larb2 | | vdec venc
When the consumer works, it should enable the smi-larb's power which also need enable the smi-common's power firstly.
Thus, First of all, use the device link connect the consumer and the smi-larbs. then add device link between the smi-larb and smi-common.
This patch adds device_link between the consumer and the larbs.
When device_link_add, I add the flag DL_FLAG_STATELESS to avoid calling pm_runtime_xx to keep the original status of clocks. It can avoid two issues:
- Display HW show fastlogo abnormally reported in [1]. At the beggining,
all the clocks are enabled before entering kernel, but the clocks for display HW(always in larb0) will be gated after clk_enable and clk_disable called from device_link_add(->pm_runtime_resume) and rpm_idle. The clock operation happened before display driver probe. At that time, the display HW will be abnormal.
- A deadlock issue reported in [2]. Use DL_FLAG_STATELESS to skip
pm_runtime_xx to avoid the deadlock.
Corresponding, DL_FLAG_AUTOREMOVE_CONSUMER can't be added, then device_link_removed should be added explicitly.
Meanwhile, Currently we don't have a device connect with 2 larbs at the same time. Disallow this case, print the error log.
[1] https://lore.kernel.org/linux-mediatek/1564213888.22908.4.camel@mhfsdcap03/ [2] https://lore.kernel.org/patchwork/patch/1086569/
Suggested-by: Tomasz Figa tfiga@chromium.org Signed-off-by: Yong Wu yong.wu@mediatek.com Tested-by: Frank Wunderlich frank-w@public-files.de # BPI-R2/MT7623
Reviewed-by: AngeloGioacchino Del Regno angelogioacchino.delregno@collabora.com