Re: [RFC 1/2] iommu/arm-smmu-v3: Remove bypass in arm_smmu_reset_device

From: Robin Murphy
Date: Mon Apr 23 2018 - 12:07:52 EST


On 23/04/18 12:45, Yisheng Xie wrote:
Add a bypass parameter in arm_smmu_device to keep whether smmu device
should pypass or not, so parameter bypass in arm_smmu_reset_device can
be removed.

Given that the GBPA configuration implied by the bypass argument here is only there to avoid initialising a full stream table when the firmware is terminally broken, I wonder if it would make sense to simply skip allocating a stream table at all in that case. Then we could just base the subsequent SMMUEN/GPBA decision on whether strtab_cfg.strtab is valid or not.

Robin.

This should not have any functional change, but prepare for later patch.

Signed-off-by: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
---
drivers/iommu/arm-smmu-v3.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 1d64710..044df6e 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -587,6 +587,8 @@ struct arm_smmu_device {
u32 sync_count;
+ bool bypass;
+
/* IOMMU core code handle */
struct iommu_device iommu;
};
@@ -2384,7 +2386,7 @@ static int arm_smmu_device_disable(struct arm_smmu_device *smmu)
return ret;
}
-static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
+static int arm_smmu_device_reset(struct arm_smmu_device *smmu)
{
int ret;
u32 reg, enables;
@@ -2487,7 +2489,7 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
/* Enable the SMMU interface, or ensure bypass */
- if (!bypass || disable_bypass) {
+ if (!smmu->bypass || disable_bypass) {
enables |= CR0_SMMUEN;
} else {
ret = arm_smmu_update_gbpa(smmu, 0, GBPA_ABORT);
@@ -2778,7 +2780,6 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
resource_size_t ioaddr;
struct arm_smmu_device *smmu;
struct device *dev = &pdev->dev;
- bool bypass;
smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
if (!smmu) {
@@ -2796,7 +2797,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
}
/* Set bypass mode according to firmware probing result */
- bypass = !!ret;
+ smmu->bypass = !!ret;
/* Base address */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -2842,7 +2843,7 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, smmu);
/* Reset the device */
- ret = arm_smmu_device_reset(smmu, bypass);
+ ret = arm_smmu_device_reset(smmu);
if (ret)
return ret;