Messages in this thread | | | Subject | Re: [PATCH v9 05/15] iommu/mediatek: Add device_link between the consumer and the larb devices | From | AngeloGioacchino Del Regno <> | Date | Tue, 11 Jan 2022 11:57:47 +0100 |
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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: > 1) 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. > > 2) 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>
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