On Tue, Oct 17, 2023 at 07:24:31AM -0700, Bjorn Andersson wrote:
> On Tue, Oct 17, 2023 at 11:47:55AM +0530, Manivannan Sadhasivam wrote:
> > From: Manivannan Sadhasivam <mani@xxxxxxxxxx>
>
> Your S-o-b should match this.
>
I gave b4 a shot for sending the patches and missed this. Will fix it in next
version.
> >
> > Qcom EP platforms require enabling/disabling the DBI CS2 access while
> > programming some read only and shadow registers through DBI. So let's
> > implement the dbi_cs2_access() callback that will be called by the DWC core
> > while programming such registers like BAR mask register.
> >
> > Without DBI CS2 access, writes to those registers will not be reflected.
> >
> > Fixes: f55fee56a631 ("PCI: qcom-ep: Add Qualcomm PCIe Endpoint controller driver")
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pcie-qcom-ep.c | 14 ++++++++++++++
> > 1 file changed, 14 insertions(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > index 32c8d9e37876..4653cbf7f9ed 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > @@ -124,6 +124,7 @@
> >
> > /* ELBI registers */
> > #define ELBI_SYS_STTS 0x08
> > +#define ELBI_CS2_ENABLE 0xa4
> >
> > /* DBI registers */
> > #define DBI_CON_STATUS 0x44
> > @@ -262,6 +263,18 @@ static void qcom_pcie_dw_stop_link(struct dw_pcie *pci)
> > disable_irq(pcie_ep->perst_irq);
> > }
> >
> > +static void qcom_pcie_dbi_cs2_access(struct dw_pcie *pci, bool enable)
> > +{
> > + struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
> > +
> > + writel_relaxed(enable, pcie_ep->elbi + ELBI_CS2_ENABLE);
>
> Don't you want to maintain the ordering of whatever write came before
> this?
>
Since this in a dedicated function, I did not care about the ordering w.r.t
previous writes. Even if it gets inlined, the order should not matter since it
only enables/disables the CS2 access for the forthcoming writes.
- Mani
> Regards,
> Bjorn
>
> > + /*
> > + * Do a dummy read to make sure that the previous write has reached the
> > + * memory before returning.
> > + */
> > + readl_relaxed(pcie_ep->elbi + ELBI_CS2_ENABLE);
> > +}
> > +
> > static void qcom_pcie_ep_icc_update(struct qcom_pcie_ep *pcie_ep)
> > {
> > struct dw_pcie *pci = &pcie_ep->pci;
> > @@ -500,6 +513,7 @@ static const struct dw_pcie_ops pci_ops = {
> > .link_up = qcom_pcie_dw_link_up,
> > .start_link = qcom_pcie_dw_start_link,
> > .stop_link = qcom_pcie_dw_stop_link,
> > + .dbi_cs2_access = qcom_pcie_dbi_cs2_access,
> > };
> >
> > static int qcom_pcie_ep_get_io_resources(struct platform_device *pdev,
> >
> > --
> > 2.25.1
> >
--
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