Hi Kishon,
On Tue, Oct 11, 2016 at 06:28:34PM +0530, Kishon Vijay Abraham I wrote:
> PCIe in AM57x/DRA7x devices is by default
> configured to work in GEN2 mode. However there
> may be situations when working in GEN1 mode is
> desired. One example is limitation i925 (PCIe GEN2
> mode not supported at junction temperatures < 0C).
>
> Add support to force Root Complex to work in GEN1
> mode if so desired, but don't force GEN1 mode on
> any board just yet.
>
> Signed-off-by: Kishon Vijay Abraham I <[email protected]>
> Signed-off-by: Sekhar Nori <[email protected]>
> ---
> Documentation/devicetree/bindings/pci/ti-pci.txt | 1 +
> drivers/pci/host/pci-dra7xx.c | 27
> ++++++++++++++++++++++
> 2 files changed, 28 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/pci/ti-pci.txt
> b/Documentation/devicetree/bindings/pci/ti-pci.txt
> index 60e2516..a3d6ca3 100644
> --- a/Documentation/devicetree/bindings/pci/ti-pci.txt
> +++ b/Documentation/devicetree/bindings/pci/ti-pci.txt
> @@ -25,6 +25,7 @@ PCIe Designware Controller
>
> Optional Property:
> - gpios : Should be added if a gpio line is required to drive PERST# line
> + - ti,pcie-is-gen1 : Force the PCIe controller to work in GEN1 (2.5 GT/s).
Can we use "max-link-speed" so it's similar to imx6?
> Example:
> axi {
> diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
> index 4ccba6d..2a669cb 100644
> --- a/drivers/pci/host/pci-dra7xx.c
> +++ b/drivers/pci/host/pci-dra7xx.c
> @@ -63,11 +63,14 @@
> #define LINK_UP BIT(16)
> #define DRA7XX_CPU_TO_BUS_ADDR 0x0FFFFFFF
>
> +#define EXP_CAP_ID_OFFSET 0x70
> +
> struct dra7xx_pcie {
> struct pcie_port pp;
> void __iomem *base; /* DT ti_conf */
> int phy_count; /* DT phy-names count */
> struct phy **phy;
> + bool is_gen1;
> };
>
> #define to_dra7xx_pcie(x) container_of((x), struct dra7xx_pcie, pp)
> @@ -96,12 +99,33 @@ static int dra7xx_pcie_establish_link(struct dra7xx_pcie
> *dra7xx_pcie)
> struct pcie_port *pp = &dra7xx_pcie->pp;
> struct device *dev = pp->dev;
> u32 reg;
> + u32 exp_cap_off = EXP_CAP_ID_OFFSET;
>
> if (dw_pcie_link_up(pp)) {
> dev_err(dev, "link is already up\n");
> return 0;
> }
>
> + if (dra7xx_pcie->is_gen1) {
> + dw_pcie_cfg_read(pp->dbi_base + exp_cap_off + PCI_EXP_LNKCAP,
> + 4, ®);
> + if ((reg & PCI_EXP_LNKCAP_SLS) != PCI_EXP_LNKCAP_SLS_2_5GB) {
> + reg &= ~((u32)PCI_EXP_LNKCAP_SLS);
> + reg |= PCI_EXP_LNKCAP_SLS_2_5GB;
> + dw_pcie_cfg_write(pp->dbi_base + exp_cap_off +
> + PCI_EXP_LNKCAP, 4, reg);
> + }
> +
> + dw_pcie_cfg_read(pp->dbi_base + exp_cap_off + PCI_EXP_LNKCTL2,
> + 2, ®);
> + if ((reg & PCI_EXP_LNKCAP_SLS) != PCI_EXP_LNKCAP_SLS_2_5GB) {
> + reg &= ~((u32)PCI_EXP_LNKCAP_SLS);
> + reg |= PCI_EXP_LNKCAP_SLS_2_5GB;
> + dw_pcie_cfg_write(pp->dbi_base + exp_cap_off +
> + PCI_EXP_LNKCTL2, 2, reg);
> + }
> + }
> +
> reg = dra7xx_pcie_readl(dra7xx_pcie, PCIECTRL_DRA7XX_CONF_DEVICE_CMD);
> reg |= LTSSM_EN;
> dra7xx_pcie_writel(dra7xx_pcie, PCIECTRL_DRA7XX_CONF_DEVICE_CMD, reg);
> @@ -402,6 +426,9 @@ static int __init dra7xx_pcie_probe(struct
> platform_device *pdev)
> reg &= ~LTSSM_EN;
> dra7xx_pcie_writel(dra7xx_pcie, PCIECTRL_DRA7XX_CONF_DEVICE_CMD, reg);
>
> + if (of_property_read_bool(np, "ti,pcie-is-gen1"))
> + dra7xx_pcie->is_gen1 = true;
> +
> ret = dra7xx_add_pcie_port(dra7xx_pcie, pdev);
> if (ret < 0)
> goto err_gpio;
> --
> 1.7.9.5
>
