Hi Rafael, On Wed, Jul 11, 2018 at 4:06 PM, Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx> wrote: > Hi Rafael, > > > > On 7/11/2018 3:23 PM, Rafael J. Wysocki wrote: >> >> On Sunday, July 8, 2018 7:34:12 PM CEST Vivek Gautam wrote: >>> >>> From: Sricharan R <sricharan@xxxxxxxxxxxxxx> >>> >>> Finally add the device link between the master device and >>> smmu, so that the smmu gets runtime enabled/disabled only when the >>> master needs it. This is done from add_device callback which gets >>> called once when the master is added to the smmu. >>> >>> Signed-off-by: Sricharan R <sricharan@xxxxxxxxxxxxxx> >>> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxxxxxxxxx> >>> Reviewed-by: Tomasz Figa <tfiga@xxxxxxxxxxxx> >>> Cc: Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> >>> Cc: Lukas Wunner <lukas@xxxxxxxxx> >>> --- >>> >>> - Change since v11 >>> * Replaced DL_FLAG_AUTOREMOVE flag with DL_FLAG_AUTOREMOVE_SUPPLIER. >>> >>> drivers/iommu/arm-smmu.c | 12 ++++++++++++ >>> 1 file changed, 12 insertions(+) >>> >>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c >>> index 09265e206e2d..916cde4954d2 100644 >>> --- a/drivers/iommu/arm-smmu.c >>> +++ b/drivers/iommu/arm-smmu.c >>> @@ -1461,8 +1461,20 @@ static int arm_smmu_add_device(struct device *dev) >>> iommu_device_link(&smmu->iommu, dev); >>> + if (pm_runtime_enabled(smmu->dev) && >> >> Why does the creation of the link depend on whether or not runtime PM >> is enabled for the MMU device? > > > The main purpose of this device link is to handle the runtime PM > synchronization > between the supplier (iommu) and consumer (client devices, such as > GPU/display). > Moreover, the runtime pm is conditionally enabled for smmu devices that > support > such [1]. Is there something you would like me to modify in this patch? Best regards Vivek >> >> >> What about system-wide PM and system shutdown? Are they always guaranteed >> to happen in the right order without the link? > > > When there's no runtime PM, there's no clocks, and other resources to be > handled. > So, we don't need device link for system-wide PM and system shutdown to work > correctly. > That's the case with current arm-smmu driver. > Is it something that i am missing here? > > [1] https://lkml.org/lkml/2018/3/8/775 > > Thanks > Vivek >>> >>> + !device_link_add(dev, smmu->dev, >>> + DL_FLAG_PM_RUNTIME | >>> DL_FLAG_AUTOREMOVE_SUPPLIER)) { >>> + dev_err(smmu->dev, "Unable to add link to the consumer >>> %s\n", >>> + dev_name(dev)); >>> + ret = -ENODEV; >>> + goto out_unlink; >>> + } >>> + >>> return 0; >>> +out_unlink: >>> + iommu_device_unlink(&smmu->iommu, dev); >>> + arm_smmu_master_free_smes(fwspec); >>> out_cfg_free: >>> kfree(cfg); >>> out_free: >>> >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
