On Mon, 2021-10-11 at 14:36 +0200, Dafna Hirschfeld wrote: > > On 29.09.21 03:37, Yong Wu wrote: > > 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. > > > > [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@xxxxxxxxxxxx> > > Signed-off-by: Yong Wu <yong.wu@xxxxxxxxxxxx> > > Tested-by: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx> # BPI- > > R2/MT7623 > > --- > > drivers/iommu/mtk_iommu.c | 22 ++++++++++++++++++++++ > > drivers/iommu/mtk_iommu_v1.c | 20 +++++++++++++++++++- > > 2 files changed, 41 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c > > index d5848f78a677..a2fa55899434 100644 > > --- a/drivers/iommu/mtk_iommu.c > > +++ b/drivers/iommu/mtk_iommu.c > > @@ -560,22 +560,44 @@ static struct iommu_device > > *mtk_iommu_probe_device(struct device *dev) > > { > > struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev); > > struct mtk_iommu_data *data; > > + struct device_link *link; > > + struct device *larbdev; > > + unsigned int larbid; > > > > if (!fwspec || fwspec->ops != &mtk_iommu_ops) > > return ERR_PTR(-ENODEV); /* Not a iommu client device > > */ > > > > data = dev_iommu_priv_get(dev); > > > > + /* > > + * Link the consumer device with the smi-larb device(supplier) > > + * The device in each a larb is a independent HW. thus only > > link > > + * one larb here. > > + */ > > + larbid = MTK_M4U_TO_LARB(fwspec->ids[0]); > > so larbid is always the same for all the ids of a device? Yes. For me, each a dtsi node should represent a HW unit which can only connect one larb. > If so maybe it worth testing it and return error if this is not the > case. Thanks for the suggestion. This is very helpful. I did see someone put the different larbs in one node. I will check this, and add return EINVAL for this case. > > Thanks, > Dafna > >
