Re: [PATCH V10 03/15] PCI: dwc: Perform dbi regs write lock towards the end

Jingoo Han
2019-06-18T06:42:45Z

On 6/12/19, 6:54 PM, Vidya Sagar wrote:
>
> Remove multiple write enable and disable sequences of dbi registers as
> Tegra194 implements writes to BAR-0 register (offset: 0x10) controlled by
> DBI write-lock enable bit thereby not allowing any further writes to BAR-0
> register in config space to take place. Hence enabling write permission at
> the start of function and disabling the same only towards the end.
>
> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
> Reviewed-by: Thierry Reding <treding@nvidia.com>

Acked-by: Jingoo Han <jingoohan1@gmail.com>

Sorry for being late. I read the previous threads. I don't think that this patch
has any harmful effects. This patch looks good to me.
Thank you.

Best regards,
Jingoo Han

> ---
> Changes since [v9]:
> * None
>
> Changes since [v8]:
> * None
>
> Changes since [v7]:
> * None
>
> Changes since [v6]:
> * None
>
> Changes since [v5]:
> * Moved write enable to the beginning of the API and write disable to the end
>
> Changes since [v4]:
> * None
>
> Changes since [v3]:
> * None
>
> Changes since [v2]:
> * None
>
> Changes since [v1]:
> * None
>
> drivers/pci/controller/dwc/pcie-designware-host.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index f93252d0da5b..d3156446ff27 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -628,6 +628,12 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
> u32 val, ctrl, num_ctrls;
> struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>
> + /*
> + * Enable DBI read-only registers for writing/updating configuration.
> + * Write permission gets disabled towards the end of this function.
> + */
> + dw_pcie_dbi_ro_wr_en(pci);
> +
> dw_pcie_setup(pci);
>
> if (!pp->ops->msi_host_init) {
> @@ -650,12 +656,10 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
> dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_1, 0x00000000);
>
> /* Setup interrupt pins */
> - dw_pcie_dbi_ro_wr_en(pci);
> val = dw_pcie_readl_dbi(pci, PCI_INTERRUPT_LINE);
> val &= 0xffff00ff;
> val |= 0x00000100;
> dw_pcie_writel_dbi(pci, PCI_INTERRUPT_LINE, val);
> - dw_pcie_dbi_ro_wr_dis(pci);
>
> /* Setup bus numbers */
> val = dw_pcie_readl_dbi(pci, PCI_PRIMARY_BUS);
> @@ -687,15 +691,13 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
>
> dw_pcie_wr_own_conf(pp, PCI_BASE_ADDRESS_0, 4, 0);
>
> - /* Enable write permission for the DBI read-only register */
> - dw_pcie_dbi_ro_wr_en(pci);
> /* Program correct class for RC */
> dw_pcie_wr_own_conf(pp, PCI_CLASS_DEVICE, 2, PCI_CLASS_BRIDGE_PCI);
> - /* Better disable write permission right after the update */
> - dw_pcie_dbi_ro_wr_dis(pci);
>
> dw_pcie_rd_own_conf(pp, PCIE_LINK_WIDTH_SPEED_CONTROL, 4, &val);
> val |= PORT_LOGIC_SPEED_CHANGE;
> dw_pcie_wr_own_conf(pp, PCIE_LINK_WIDTH_SPEED_CONTROL, 4, val);
> +
> + dw_pcie_dbi_ro_wr_dis(pci);
> }
> EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
> --
> 2.17.1