Re: [PATCH v4] iommu/of: Fix pci_request_acs() before enumerating PCI devices
From: Anders Roxell
Date: Thu Sep 02 2021 - 08:51:58 EST
On Wed, 1 Sept 2021 at 11:58, Robin Murphy <robin.murphy@xxxxxxx> wrote:
> On 2021-09-01 09:59, Marek Szyprowski wrote:
> > On 21.05.2021 05:03, Wang Xingang wrote:
> >> From: Xingang Wang <wangxingang5@xxxxxxxxxx>
> >> When booting with devicetree, the pci_request_acs() is called after the
> >> enumeration and initialization of PCI devices, thus the ACS is not
> >> enabled. And ACS should be enabled when IOMMU is detected for the
> >> PCI host bridge, so add check for IOMMU before probe of PCI host and call
> >> pci_request_acs() to make sure ACS will be enabled when enumerating PCI
> >> devices.
> >> Fixes: 6bf6c24720d33 ("iommu/of: Request ACS from the PCI core when
> >> configuring IOMMU linkage")
> >> Signed-off-by: Xingang Wang <wangxingang5@xxxxxxxxxx>
> > This patch landed in linux-next as commit 57a4ab1584e6 ("iommu/of: Fix
> > pci_request_acs() before enumerating PCI devices"). Sadly it breaks PCI
> > operation on ARM Juno R1 board (arch/arm64/boot/dts/arm/juno-r1.dts). It
We've seen this on ARM Juno R2 boards too in the Linaro testfarm.
The problem is that the device can't get the "SATA link up" while booting.
When reverting this patch we are able to see the "SATA link up".