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

[Vidya Sagar <vidyas@nvidia.com>]

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?

- Vidya Sagar

> +		dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> +	}
> +
>   	val = dw_pcie_readl_dbi(pci, PCIE_PORT_LINK_CONTROL);
>   	val &= ~PORT_LINK_FAST_LINK_MODE;
>   	val |= PORT_LINK_DLL_LINK_EN;
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 0b48298362cd..d8771db247f4 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -34,6 +34,7 @@
>   #define PORT_AFR_N_FTS_MASK		GENMASK(15, 8)
>   #define PORT_AFR_N_FTS(n)		FIELD_PREP(PORT_AFR_N_FTS_MASK, n)
>   #define PORT_AFR_CC_N_FTS_MASK		GENMASK(23, 16)
> +#define PORT_AFR_CC_N_FTS(n)		FIELD_PREP(PORT_AFR_CC_N_FTS_MASK, n)
>   #define PORT_AFR_ENTER_ASPM		BIT(30)
>   #define PORT_AFR_L0S_ENTRANCE_LAT_SHIFT	24
>   #define PORT_AFR_L0S_ENTRANCE_LAT_MASK	GENMASK(26, 24)
> @@ -253,6 +254,7 @@ struct dw_pcie {
>   	unsigned int		version;
>   	int			num_lanes;
>   	int			link_gen;
> +	u8			n_fts[2];
>   };
>   
>   #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)
> @@ -271,7 +273,6 @@ void dw_pcie_write_dbi(struct dw_pcie *pci, u32 reg, size_t size, u32 val);
>   void dw_pcie_write_dbi2(struct dw_pcie *pci, u32 reg, size_t size, u32 val);
>   int dw_pcie_link_up(struct dw_pcie *pci);
>   void dw_pcie_upconfig_setup(struct dw_pcie *pci);
> -void dw_pcie_link_set_n_fts(struct dw_pcie *pci, u32 n_fts);
>   int dw_pcie_wait_for_link(struct dw_pcie *pci);
>   void dw_pcie_prog_outbound_atu(struct dw_pcie *pci, int index,
>   			       int type, u64 cpu_addr, u64 pci_addr,
> diff --git a/drivers/pci/controller/dwc/pcie-intel-gw.c b/drivers/pci/controller/dwc/pcie-intel-gw.c
> index 333f11561807..5650cb78acba 100644
> --- a/drivers/pci/controller/dwc/pcie-intel-gw.c
> +++ b/drivers/pci/controller/dwc/pcie-intel-gw.c
> @@ -67,7 +67,6 @@ struct intel_pcie_port {
>   	void __iomem		*app_base;
>   	struct gpio_desc	*reset_gpio;
>   	u32			rst_intrvl;
> -	u32			n_fts;
>   	struct clk		*core_clk;
>   	struct reset_control	*core_rst;
>   	struct phy		*phy;
> @@ -138,37 +137,29 @@ static void intel_pcie_link_setup(struct intel_pcie_port *lpp)
>   	pcie_rc_cfg_wr(lpp, offset + PCI_EXP_LNKCTL, val);
>   }
>   
> -static void intel_pcie_port_logic_setup(struct intel_pcie_port *lpp)
> +static void intel_pcie_init_n_fts(struct dw_pcie *pci)
>   {
> -	u32 val, mask;
> -	struct dw_pcie *pci = &lpp->pci;
> -
> -	switch (pcie_link_speed[pci->link_gen]) {
> -	case PCIE_SPEED_8_0GT:
> -		lpp->n_fts = PORT_AFR_N_FTS_GEN3;
> +	switch (pci->link_gen) {
> +	case 3:
> +		pci->n_fts[1] = PORT_AFR_N_FTS_GEN3;
>   		break;
> -	case PCIE_SPEED_16_0GT:
> -		lpp->n_fts = PORT_AFR_N_FTS_GEN4;
> +	case 4:
> +		pci->n_fts[1] = PORT_AFR_N_FTS_GEN4;
>   		break;
>   	default:
> -		lpp->n_fts = PORT_AFR_N_FTS_GEN12_DFT;
> +		pci->n_fts[1] = PORT_AFR_N_FTS_GEN12_DFT;
>   		break;
>   	}
> -
> -	mask = PORT_AFR_N_FTS_MASK | PORT_AFR_CC_N_FTS_MASK;
> -	val = FIELD_PREP(PORT_AFR_N_FTS_MASK, lpp->n_fts) |
> -	       FIELD_PREP(PORT_AFR_CC_N_FTS_MASK, lpp->n_fts);
> -	pcie_rc_cfg_wr_mask(lpp, PCIE_PORT_AFR, mask, val);
> +	pci->n_fts[0] = PORT_AFR_N_FTS_GEN12_DFT;
>   }
>   
>   static void intel_pcie_rc_setup(struct intel_pcie_port *lpp)
>   {
>   	intel_pcie_ltssm_disable(lpp);
>   	intel_pcie_link_setup(lpp);
> +	intel_pcie_init_n_fts(&lpp->pci);
>   	dw_pcie_setup_rc(&lpp->pci.pp);
>   	dw_pcie_upconfig_setup(&lpp->pci);
> -	intel_pcie_port_logic_setup(lpp);
> -	dw_pcie_link_set_n_fts(&lpp->pci, lpp->n_fts);
>   }
>   
>   static int intel_pcie_ep_rst_init(struct intel_pcie_port *lpp)
> diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> index 91ef4b3e860d..1560c449757d 100644
> --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> @@ -881,17 +881,6 @@ static void tegra_pcie_prepare_host(struct pcie_port *pp)
>   
>   	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 0);
>   
> -	/* Configure FTS */
> -	val = dw_pcie_readl_dbi(pci, PCIE_PORT_AFR);
> -	val &= ~PORT_AFR_N_FTS_MASK;
> -	val |= PORT_AFR_N_FTS(N_FTS_VAL);
> -	dw_pcie_writel_dbi(pci, PCIE_PORT_AFR, val);
> -
> -	val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
> -	val &= ~PORT_LOGIC_N_FTS_MASK;
> -	val |= FTS_VAL;
> -	dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> -
>   	/* Enable as 0xFFFF0001 response for CRS */
>   	val = dw_pcie_readl_dbi(pci, PORT_LOGIC_AMBA_ERROR_RESPONSE_DEFAULT);
>   	val &= ~(AMBA_ERROR_RESPONSE_CRS_MASK << AMBA_ERROR_RESPONSE_CRS_SHIFT);
> @@ -1794,17 +1783,6 @@ static void pex_ep_event_pex_rst_deassert(struct tegra_pcie_dw *pcie)
>   	val &= ~GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL;
>   	dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, val);
>   
> -	/* Configure N_FTS & FTS */
> -	val = dw_pcie_readl_dbi(pci, PCIE_PORT_AFR);
> -	val &= ~PORT_AFR_N_FTS_MASK;
> -	val |= PORT_AFR_N_FTS(FTS_VAL);
> -	dw_pcie_writel_dbi(pci, PCIE_PORT_AFR, val);
> -
> -	val = dw_pcie_readl_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL);
> -	val &= ~PORT_LOGIC_N_FTS_MASK;
> -	val |= FTS_VAL;
> -	dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, val);
> -
>   	pcie->pcie_cap_base = dw_pcie_find_capability(&pcie->pci,
>   						      PCI_CAP_ID_EXP);
>   	clk_set_rate(pcie->core_clk, GEN4_CORE_CLK_FREQ);
> @@ -2033,6 +2011,9 @@ static int tegra_pcie_dw_probe(struct platform_device *pdev)
>   	pci = &pcie->pci;
>   	pci->dev = &pdev->dev;
>   	pci->ops = &tegra_dw_pcie_ops;
> +	pci->n_fts[0] = N_FTS_VAL;
> +	pci->n_fts[1] = FTS_VAL;
> +
>   	pp = &pci->pp;
>   	pcie->dev = &pdev->dev;
>   	pcie->mode = (enum dw_pcie_device_mode)data->mode;
>