Re: [PATCH 1/1] PCI: iproc: Invalidate PAXB address mapping before programming it

From: Lorenzo Pieralisi
Date: Tue Oct 15 2019 - 12:43:09 EST


On Fri, Sep 06, 2019 at 09:28:13AM +0530, Abhishek Shah wrote:
> Invalidate PAXB inbound/outbound address mapping each time before
> programming it. This is helpful for the cases where we need to
> reprogram inbound/outbound address mapping without resetting PAXB.
> kexec kernel is one such example.

This looks like a hack, explain to us please what it actually solves and
why a full reset is not necessary.

> Signed-off-by: Abhishek Shah <abhishek.shah@xxxxxxxxxxxx>
> Reviewed-by: Ray Jui <ray.jui@xxxxxxxxxxxx>
> Reviewed-by: Vikram Mysore Prakash <vikram.prakash@xxxxxxxxxxxx>

Patches are reviewed on public mailing lists, remove tags given
on internal reviews - they are not relevant.

> ---
> drivers/pci/controller/pcie-iproc.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/drivers/pci/controller/pcie-iproc.c b/drivers/pci/controller/pcie-iproc.c
> index e3ca46497470..99a9521ba7ab 100644
> --- a/drivers/pci/controller/pcie-iproc.c
> +++ b/drivers/pci/controller/pcie-iproc.c
> @@ -1245,6 +1245,32 @@ static int iproc_pcie_map_dma_ranges(struct iproc_pcie *pcie)
> return ret;
> }
>
> +static void iproc_pcie_invalidate_mapping(struct iproc_pcie *pcie)
> +{
> + struct iproc_pcie_ib *ib = &pcie->ib;
> + struct iproc_pcie_ob *ob = &pcie->ob;
> + int idx;
> +
> + if (pcie->ep_is_internal)

What's this check for and why leaving mappings in place is safe for
this category of IPs ?

> + return;
> +
> + if (pcie->need_ob_cfg) {
> + /* iterate through all OARR mapping regions */
> + for (idx = ob->nr_windows - 1; idx >= 0; idx--) {
> + iproc_pcie_write_reg(pcie,
> + MAP_REG(IPROC_PCIE_OARR0, idx), 0);
> + }
> + }
> +
> + if (pcie->need_ib_cfg) {
> + /* iterate through all IARR mapping regions */
> + for (idx = 0; idx < ib->nr_regions; idx++) {
> + iproc_pcie_write_reg(pcie,
> + MAP_REG(IPROC_PCIE_IARR0, idx), 0);
> + }
> + }
> +}
> +
> static int iproce_pcie_get_msi(struct iproc_pcie *pcie,
> struct device_node *msi_node,
> u64 *msi_addr)
> @@ -1517,6 +1543,8 @@ int iproc_pcie_setup(struct iproc_pcie *pcie, struct list_head *res)
> iproc_pcie_perst_ctrl(pcie, true);
> iproc_pcie_perst_ctrl(pcie, false);
>
> + iproc_pcie_invalidate_mapping(pcie);

It makes more sense to call this in the .shutdown() method if I
understand what it does.

Lorenzo

> if (pcie->need_ob_cfg) {
> ret = iproc_pcie_map_ranges(pcie, res);
> if (ret) {
> --
> 2.17.1
>