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Date: Tue, 17 Dec 2019 11:58:27 +0000
From: Andrew Murray <andrew.murray@....com>
To: Kishon Vijay Abraham I <kishon@...com>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
Rob Herring <robh+dt@...nel.org>,
Arnd Bergmann <arnd@...db.de>, linux-pci@...r.kernel.org,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-omap@...r.kernel.org
Subject: Re: [PATCH 04/13] PCI: cadence: Add support to start link and verify
link status
On Mon, Dec 09, 2019 at 02:51:38PM +0530, Kishon Vijay Abraham I wrote:
> Add cdns_pcie_ops to start link and verify link status. The registers
> to start link and to check link status is in Platform specific PCIe
> wrapper. Add support for platform specific drivers to add callback
> functions for the PCIe Cadence core to start link and verify link status.
>
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> ---
> .../pci/controller/cadence/pcie-cadence-ep.c | 8 ++++++
> .../controller/cadence/pcie-cadence-host.c | 28 +++++++++++++++++++
> drivers/pci/controller/cadence/pcie-cadence.h | 23 +++++++++++++++
> 3 files changed, 59 insertions(+)
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> index 560f22b4d165..088394b6be04 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> @@ -355,8 +355,10 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
> {
> struct cdns_pcie_ep *ep = epc_get_drvdata(epc);
> struct cdns_pcie *pcie = &ep->pcie;
> + struct device *dev = pcie->dev;
> struct pci_epf *epf;
> u32 cfg;
> + int ret;
>
> /*
> * BIT(0) is hardwired to 1, hence function 0 is always enabled
> @@ -367,6 +369,12 @@ static int cdns_pcie_ep_start(struct pci_epc *epc)
> cfg |= BIT(epf->func_no);
> cdns_pcie_writel(pcie, CDNS_PCIE_LM_EP_FUNC_CFG, cfg);
>
> + ret = cdns_pcie_start_link(pcie, true);
> + if (ret) {
> + dev_err(dev, "Failed to start link\n");
> + return ret;
> + }
> +
> return 0;
> }
>
> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> index ccf55e143e1d..0929554f5a81 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> @@ -3,6 +3,7 @@
> // Cadence PCIe host controller driver.
> // Author: Cyrille Pitchen <cyrille.pitchen@...e-electrons.com>
>
> +#include <linux/delay.h>
> #include <linux/kernel.h>
> #include <linux/of_address.h>
> #include <linux/of_pci.h>
> @@ -201,6 +202,23 @@ static int cdns_pcie_host_init(struct device *dev,
> return err;
> }
>
> +static int cdns_pcie_host_wait_for_link(struct cdns_pcie *pcie)
> +{
> + struct device *dev = pcie->dev;
> + int retries;
> +
> + /* Check if the link is up or not */
> + for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
> + if (cdns_pcie_is_link_up(pcie)) {
> + dev_info(dev, "Link up\n");
> + return 0;
> + }
> + usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
> + }
> +
> + return -ETIMEDOUT;
> +}
This patch looks fine, except this function (above) is identical to
dw_pcie_wait_for_link, advk_pcie_wait_for_link and nwl_wait_for_link. Even
the definitions of LINK_WAIT_USLEEP_xx are the same.
I don't see any justification to duplicating this again - can you consolidate
these functions to something that all controller drivers can use?
Thanks,
Andrew Murray
> +
> int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
> {
> struct device *dev = rc->pcie.dev;
> @@ -254,6 +272,16 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
>
> pcie->mem_res = res;
>
> + ret = cdns_pcie_start_link(pcie, true);
> + if (ret) {
> + dev_err(dev, "Failed to start link\n");
> + return ret;
> + }
> +
> + ret = cdns_pcie_host_wait_for_link(pcie);
> + if (ret)
> + dev_dbg(dev, "PCIe link never came up\n");
> +
> ret = cdns_pcie_host_init(dev, &resources, rc);
> if (ret)
> goto err_init;
> diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> index d0d91c69fa1d..f0395eaf9df5 100644
> --- a/drivers/pci/controller/cadence/pcie-cadence.h
> +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> @@ -10,6 +10,11 @@
> #include <linux/pci.h>
> #include <linux/phy/phy.h>
>
> +/* Parameters for the waiting for link up routine */
> +#define LINK_WAIT_MAX_RETRIES 10
> +#define LINK_WAIT_USLEEP_MIN 90000
> +#define LINK_WAIT_USLEEP_MAX 100000
> +
> /*
> * Local Management Registers
> */
> @@ -226,6 +231,8 @@ enum cdns_pcie_msg_routing {
> struct cdns_pcie_ops {
> u32 (*read)(void __iomem *addr, int size);
> void (*write)(void __iomem *addr, int size, u32 value);
> + int (*start_link)(struct cdns_pcie *pcie, bool start);
> + bool (*is_link_up)(struct cdns_pcie *pcie);
> };
>
> /**
> @@ -447,6 +454,22 @@ static inline u32 cdns_pcie_ep_fn_readl(struct cdns_pcie *pcie, u8 fn, u32 reg)
> return readl(addr);
> }
>
> +static inline int cdns_pcie_start_link(struct cdns_pcie *pcie, bool start)
> +{
> + if (pcie->ops->start_link)
> + return pcie->ops->start_link(pcie, start);
> +
> + return 0;
> +}
> +
> +static inline bool cdns_pcie_is_link_up(struct cdns_pcie *pcie)
> +{
> + if (pcie->ops->is_link_up)
> + return pcie->ops->is_link_up(pcie);
> +
> + return true;
> +}
> +
> #ifdef CONFIG_PCIE_CADENCE_HOST
> int cdns_pcie_host_setup(struct cdns_pcie_rc *rc);
> #else
> --
> 2.17.1
>
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