Re: [PATCH v2 39/40] PCI: dwc: Move N_FTS setup to common setup

[Rob Herring <robh@kernel.org>]

On Sun, Aug 8, 2021 at 9:01 AM Vidya Sagar <vidyas@nvidia.com> wrote:
>
>
>
> On 8/21/2020 9:24 AM, Rob Herring wrote:
> > The Designware controller has common registers to set number of fast
> > training sequence ordered sets. The Artpec6, Intel, and Tegra driver
> > initialize these register fields. Let's move the initialization to the
> > common setup code and drivers just have to provide the value.
> >
> > There's a slight change in that the common clock mode N_FTS field is
> > now initialized. Previously only the Intel driver set this. It's not
> > clear from the code if common clock mode is used in the Artpec6 or Tegra
> > driver. It depends on the DWC configuration. Given the field is not
> > initialized while the others are, it seems unlikely common clock mode
> > is used.
> >
> > Cc: Jesper Nilsson <jesper.nilsson@axis.com>
> > Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> > Cc: Bjorn Helgaas <bhelgaas@google.com>
> > Cc: Jingoo Han <jingoohan1@gmail.com>
> > Cc: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> > Cc: Thierry Reding <thierry.reding@gmail.com>
> > Cc: Jonathan Hunter <jonathanh@nvidia.com>
> > Cc: linux-tegra@vger.kernel.org
> > Signed-off-by: Rob Herring <robh@kernel.org>
> > ---
> >   drivers/pci/controller/dwc/pcie-artpec6.c    | 37 +++-----------------
> >   drivers/pci/controller/dwc/pcie-designware.c | 28 +++++++++------
> >   drivers/pci/controller/dwc/pcie-designware.h |  3 +-
> >   drivers/pci/controller/dwc/pcie-intel-gw.c   | 27 +++++---------
> >   drivers/pci/controller/dwc/pcie-tegra194.c   | 25 ++-----------
> >   5 files changed, 35 insertions(+), 85 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-artpec6.c b/drivers/pci/controller/dwc/pcie-artpec6.c
> > index 86f4d66d8587..929448e9e0bc 100644
> > --- a/drivers/pci/controller/dwc/pcie-artpec6.c
> > +++ b/drivers/pci/controller/dwc/pcie-artpec6.c
> > @@ -44,13 +44,6 @@ struct artpec_pcie_of_data {
> >
> >   static const struct of_device_id artpec6_pcie_of_match[];
> >
> > -/* PCIe Port Logic registers (memory-mapped) */
> > -#define PL_OFFSET                    0x700
> > -
> > -#define ACK_F_ASPM_CTRL_OFF          (PL_OFFSET + 0xc)
> > -#define ACK_N_FTS_MASK                       GENMASK(15, 8)
> > -#define ACK_N_FTS(x)                 (((x) << 8) & ACK_N_FTS_MASK)
> > -
> >   /* ARTPEC-6 specific registers */
> >   #define PCIECFG                             0x18
> >   #define  PCIECFG_DBG_OEN            BIT(24)
> > @@ -289,30 +282,6 @@ static void artpec6_pcie_init_phy(struct artpec6_pcie *artpec6_pcie)
> >       }
> >   }
> >
> > -static void artpec6_pcie_set_nfts(struct artpec6_pcie *artpec6_pcie)
> > -{
> > -     struct dw_pcie *pci = artpec6_pcie->pci;
> > -     u32 val;
> > -
> > -     if (artpec6_pcie->variant != ARTPEC7)
> > -             return;
> > -
> > -     /*
> > -      * Increase the N_FTS (Number of Fast Training Sequences)
> > -      * to be transmitted when transitioning from L0s to L0.
> > -      */
> > -     val = dw_pcie_readl_dbi(pci, ACK_F_ASPM_CTRL_OFF);
> > -     val &= ~ACK_N_FTS_MASK;
> > -     val |= ACK_N_FTS(180);
> > -     dw_pcie_writel_dbi(pci, ACK_F_ASPM_CTRL_OFF, val);
> > -
> > -     /*
> > -      * Set the Number of Fast Training Sequences that the core
> > -      * advertises as its N_FTS during Gen2 or Gen3 link training.
> > -      */
> > -     dw_pcie_link_set_n_fts(pci, 180);
> > -}
> > -
> >   static void artpec6_pcie_assert_core_reset(struct artpec6_pcie *artpec6_pcie)
> >   {
> >       u32 val;
> > @@ -351,11 +320,14 @@ static int artpec6_pcie_host_init(struct pcie_port *pp)
> >       struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> >       struct artpec6_pcie *artpec6_pcie = to_artpec6_pcie(pci);
> >
> > +     if (artpec6_pcie->variant == ARTPEC7) {
> > +             pci->n_fts[0] = 180;
> > +             pci->n_fts[1] = 180;
> > +     }
> >       artpec6_pcie_assert_core_reset(artpec6_pcie);
> >       artpec6_pcie_init_phy(artpec6_pcie);
> >       artpec6_pcie_deassert_core_reset(artpec6_pcie);
> >       artpec6_pcie_wait_for_phy(artpec6_pcie);
> > -     artpec6_pcie_set_nfts(artpec6_pcie);
> >       dw_pcie_setup_rc(pp);
> >       artpec6_pcie_establish_link(pci);
> >       dw_pcie_wait_for_link(pci);
> > @@ -403,7 +375,6 @@ static void artpec6_pcie_ep_init(struct dw_pcie_ep *ep)
> >       artpec6_pcie_init_phy(artpec6_pcie);
> >       artpec6_pcie_deassert_core_reset(artpec6_pcie);
> >       artpec6_pcie_wait_for_phy(artpec6_pcie);
> > -     artpec6_pcie_set_nfts(artpec6_pcie);
> >
> >       for (bar = 0; bar < PCI_STD_NUM_BARS; bar++)
> >               dw_pcie_ep_reset_bar(pci, bar);
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
> > index 61e1faba15bf..3cb21247619c 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware.c
> > @@ -510,17 +510,6 @@ static void dw_pcie_link_set_max_speed(struct dw_pcie *pci, u32 link_gen)
> >   }
> >   EXPORT_SYMBOL_GPL(dw_pcie_link_set_max_speed);
> >
> > -void dw_pcie_link_set_n_fts(struct dw_pcie *pci, u32 n_fts)
> > -{
> > -     u32 val;
> > -
> > -     val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
> > -     val &= ~PORT_LOGIC_N_FTS_MASK;
> > -     val |= n_fts & PORT_LOGIC_N_FTS_MASK;
> > -     dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> > -}
> > -EXPORT_SYMBOL_GPL(dw_pcie_link_set_n_fts);
> > -
> >   static u8 dw_pcie_iatu_unroll_enabled(struct dw_pcie *pci)
> >   {
> >       u32 val;
> > @@ -551,6 +540,23 @@ void dw_pcie_setup(struct dw_pcie *pci)
> >       if (pci->link_gen > 0)
> >               dw_pcie_link_set_max_speed(pci, pci->link_gen);
> >
> > +     /* Configure Gen1 N_FTS */
> > +     if (pci->n_fts[0]) {
> > +             val = dw_pcie_readl_dbi(pci, PCIE_PORT_AFR);
> > +             val &= ~(PORT_AFR_N_FTS_MASK | PORT_AFR_CC_N_FTS_MASK);
> > +             val |= PORT_AFR_N_FTS(pci->n_fts[0]);
> > +             val |= PORT_AFR_CC_N_FTS(pci->n_fts[0]);
> > +             dw_pcie_writel_dbi(pci, PCIE_PORT_AFR, val);
> > +     }
> > +
> > +     /* Configure Gen2+ N_FTS */
> > +     if (pci->n_fts[1]) {
> > +             val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
> > +             val &= ~PORT_LOGIC_N_FTS_MASK;
> > +             val |= pci->n_fts[pci->link_gen - 1];
> Apologies for getting late to this change given that the change has
> already been merged.
> I'm wondering why is it that link_gen has to be used in deriving the
> index instead of directly using '1' as the index?
> Infact the for link speed greater than 2, accesses go beyond n_fts[]
> array boundaries.
> Since the if() check is done based on a non-zero value of pci->n_fts[1],
> shouldn't the same be used for programming also?

Yes, I think you are right.

Rob