[+cc Kishon, Richard, Lucas, Dilip]
On Mon, Mar 01, 2021 at 11:10:31AM +0800, Jisheng Zhang wrote:
> After we move dw_pcie_msi_init() into core -- dw_pcie_host_init(), the
> MSI stops working after resume. Because dw_pcie_host_init() is only
> called once during probe. To fix this issue, we move dw_pcie_msi_init()
> to dw_pcie_setup_rc().
This patch looks fine, but I don't think the commit log tells the
whole story.
Prior to 59fbab1ae40e, it looks like the only dwc-based drivers with
resume functions were dra7xx, imx6, intel-gw, and tegra [1].
Only tegra called dw_pcie_msi_init() in the resume path, and I do
think 59fbab1ae40e broke MSI after resume because it removed the
dw_pcie_msi_init() call from tegra_pcie_enable_msi_interrupts().
I'm not convinced this patch fixes it reliably, though. The call
chain looks like this:
tegra_pcie_dw_resume_noirq
tegra_pcie_dw_start_link
if (dw_pcie_wait_for_link(pci))
dw_pcie_setup_rc
dw_pcie_wait_for_link() returns 0 if the link is up, so we only call
dw_pcie_setup_rc() in the case where the link *didn't* come up. If
the link comes up nicely without retry, we won't call
dw_pcie_setup_rc() and hence won't call dw_pcie_msi_init().
Since then, exynos added a resume function. My guess is MSI never
worked after resume for dra7xx, exynos, imx6, and intel-gw because
they don't call dw_pcie_msi_init() in their resume functions.
This patch looks like it should fix MSI after resume for exynos, imx6,
and intel-gw because they *do* call dw_pcie_setup_rc() from their
resume functions [2], and after this patch, dw_pcie_msi_init() will be
called from there.
I suspect MSI after resume still doesn't work on dra7xx.
[1] git grep -A20 -e "static.*resume_noirq" 59fbab1ae40e^:drivers/pci/controller/dwc
[2] git grep -A20 -e "static.*resume_noirq" drivers/pci/controller/dwc
> Fixes: 59fbab1ae40e ("PCI: dwc: Move dw_pcie_msi_init() into core")
> Reviewed-by: Rob Herring <robh@xxxxxxxxxx>
> Signed-off-by: Jisheng Zhang <Jisheng.Zhang@xxxxxxxxxxxxx>
> ---
> Since v1:
> - collect Reviewed-by tag
>
> drivers/pci/controller/dwc/pcie-designware-host.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 7e55b2b66182..e6c274f4485c 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -400,7 +400,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
> }
>
> dw_pcie_setup_rc(pp);
> - dw_pcie_msi_init(pp);
>
> if (!dw_pcie_link_up(pci) && pci->ops && pci->ops->start_link) {
> ret = pci->ops->start_link(pci);
> @@ -551,6 +550,8 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
> }
> }
>
> + dw_pcie_msi_init(pp);
> +
> /* Setup RC BARs */
> dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 0x00000004);
> dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_1, 0x00000000);
> --
> 2.30.1
>
