Subject: [PATCH v2] PCI: designware: add host_init error handling

From: [email-masked] (Jisheng Zhang)
Date: Thu, 8 Dec 2016 15:24:51 +0800

Hi Srinivas,

On Wed,  7 Dec 2016 10:32:49 +0000 Srinivas Kandagatla wrote:

> This patch add support to return value from host_init() callback from drivers,
> so that the designware libary can handle or pass it to proper place. Issue with
> void return type is that errors or error handling within host_init() callback
> are never know to designware code, which could go ahead and access registers
> even in error cases.
> 
> Typical case in qcom controller driver is to turn off clks in case of errors,

I have similar idea last year

https://patchwork.kernel.org/patch/7602421/

But finally I dropped the patch. The reason is PCIe supports hotplug. I
noticed that most *errors* are due to the link can't be established, for
example, the exynos, dra7xx in your below patch. I think FAIL_TO_ESTABLISH_LINK
is a normal case if we didn't plug in the PCIe DP, then in this case I think
it can't be considered as *error* and we still need to continue. What about
your opinion?

Thanks,
Jisheng

> if designware code continues to read/write register when clocks are turned off
> the board would reboot/lockup.
> 
> Signed-off-by: Srinivas Kandagatla <[email-masked]>
> ---
> Currently designware code does not have a way return errors generated
> as part of host_init() callback in controller drivers. This is an issue
> with controller drivers like qcom which turns off the clocks in error
> handling path. As the dw core is un aware of this would continue to
> access registers which faults resulting in board reboots/hangs.
> 
> There are two ways to solve this issue,
> one is remove error handling in the qcom controller host_init() function
> other is to handle error and pass back to dw core code which would then
> pass back to controller driver as part of dw_pcie_host_init() return value.
> 
> Second option seems more sensible and correct way to fix the issue,
> this patch does the same.
> 
> As part of this change to host_init() return type I had to patch other
> ihost controller drivers which use dw core. Most of the changes to other drivers
> are to return proper error codes to upper layer.
> Only compile tested drivers.
> 
> Changes since RFC:
> 	- Add error handling to other drivers as suggested by Joao Pinto
> 
>  drivers/pci/host/pci-dra7xx.c           | 10 ++++++++--
>  drivers/pci/host/pci-exynos.c           | 10 ++++++++--
>  drivers/pci/host/pci-imx6.c             | 10 ++++++++--
>  drivers/pci/host/pci-keystone.c         | 10 ++++++++--
>  drivers/pci/host/pci-layerscape.c       | 22 +++++++++++++---------
>  drivers/pci/host/pcie-armada8k.c        |  4 +++-
>  drivers/pci/host/pcie-designware-plat.c | 10 ++++++++--
>  drivers/pci/host/pcie-designware.c      |  4 +++-
>  drivers/pci/host/pcie-designware.h      |  2 +-
>  drivers/pci/host/pcie-qcom.c            |  5 +++--
>  drivers/pci/host/pcie-spear13xx.c       | 10 ++++++++--
>  11 files changed, 71 insertions(+), 26 deletions(-)
> 
> diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
> index 9595fad..811f0f9 100644
> --- a/drivers/pci/host/pci-dra7xx.c
> +++ b/drivers/pci/host/pci-dra7xx.c
> @@ -127,9 +127,10 @@ static void dra7xx_pcie_enable_interrupts(struct dra7xx_pcie *dra7xx)
>  				   LEG_EP_INTERRUPTS);
>  }
>  
> -static void dra7xx_pcie_host_init(struct pcie_port *pp)
> +static int dra7xx_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pp);
> +	int ret;
>  
>  	pp->io_base &= DRA7XX_CPU_TO_BUS_ADDR;
>  	pp->mem_base &= DRA7XX_CPU_TO_BUS_ADDR;
> @@ -138,10 +139,15 @@ static void dra7xx_pcie_host_init(struct pcie_port *pp)
>  
>  	dw_pcie_setup_rc(pp);
>  
> -	dra7xx_pcie_establish_link(dra7xx);
> +	ret = dra7xx_pcie_establish_link(dra7xx);
> +	if (ret < 0)
> +		return ret;
> +
>  	if (IS_ENABLED(CONFIG_PCI_MSI))
>  		dw_pcie_msi_init(pp);
>  	dra7xx_pcie_enable_interrupts(dra7xx);
> +
> +	return 0;
>  }
>  
>  static struct pcie_host_ops dra7xx_pcie_host_ops = {
> diff --git a/drivers/pci/host/pci-exynos.c b/drivers/pci/host/pci-exynos.c
> index f1c544b..c116fd9 100644
> --- a/drivers/pci/host/pci-exynos.c
> +++ b/drivers/pci/host/pci-exynos.c
> @@ -458,12 +458,18 @@ static int exynos_pcie_link_up(struct pcie_port *pp)
>  	return 0;
>  }
>  
> -static void exynos_pcie_host_init(struct pcie_port *pp)
> +static int exynos_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct exynos_pcie *exynos_pcie = to_exynos_pcie(pp);
> +	int ret;
> +
> +	ret = exynos_pcie_establish_link(exynos_pcie);
> +	if (ret < 0)
> +		return ret;
>  
> -	exynos_pcie_establish_link(exynos_pcie);
>  	exynos_pcie_enable_interrupts(exynos_pcie);
> +
> +	return 0;
>  }
>  
>  static struct pcie_host_ops exynos_pcie_host_ops = {
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index c8cefb0..1251e92 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -550,18 +550,24 @@ static int imx6_pcie_establish_link(struct imx6_pcie *imx6_pcie)
>  	return ret;
>  }
>  
> -static void imx6_pcie_host_init(struct pcie_port *pp)
> +static int imx6_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
> +	int ret;
>  
>  	imx6_pcie_assert_core_reset(imx6_pcie);
>  	imx6_pcie_init_phy(imx6_pcie);
>  	imx6_pcie_deassert_core_reset(imx6_pcie);
>  	dw_pcie_setup_rc(pp);
> -	imx6_pcie_establish_link(imx6_pcie);
> +	ret = imx6_pcie_establish_link(imx6_pcie);
> +
> +	if (ret < 0)
> +		return ret;
>  
>  	if (IS_ENABLED(CONFIG_PCI_MSI))
>  		dw_pcie_msi_init(pp);
> +
> +	return 0;
>  }
>  
>  static int imx6_pcie_link_up(struct pcie_port *pp)
> diff --git a/drivers/pci/host/pci-keystone.c b/drivers/pci/host/pci-keystone.c
> index 043c19a..4067a75 100644
> --- a/drivers/pci/host/pci-keystone.c
> +++ b/drivers/pci/host/pci-keystone.c
> @@ -260,12 +260,16 @@ static int keystone_pcie_fault(unsigned long addr, unsigned int fsr,
>  	return 0;
>  }
>  
> -static void __init ks_pcie_host_init(struct pcie_port *pp)
> +static int __init ks_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct keystone_pcie *ks_pcie = to_keystone_pcie(pp);
>  	u32 val;
> +	int ret;
> +
> +	ret = ks_pcie_establish_link(ks_pcie);
> +	if (ret < 0)
> +		return ret;
>  
> -	ks_pcie_establish_link(ks_pcie);
>  	ks_dw_pcie_setup_rc_app_regs(ks_pcie);
>  	ks_pcie_setup_interrupts(ks_pcie);
>  	writew(PCI_IO_RANGE_TYPE_32 | (PCI_IO_RANGE_TYPE_32 << 8),
> @@ -287,6 +291,8 @@ static void __init ks_pcie_host_init(struct pcie_port *pp)
>  	 */
>  	hook_fault_code(17, keystone_pcie_fault, SIGBUS, 0,
>  			"Asynchronous external abort");
> +
> +	return 0;
>  }
>  
>  static struct pcie_host_ops keystone_pcie_host_ops = {
> diff --git a/drivers/pci/host/pci-layerscape.c b/drivers/pci/host/pci-layerscape.c
> index 6537079..60c8b84 100644
> --- a/drivers/pci/host/pci-layerscape.c
> +++ b/drivers/pci/host/pci-layerscape.c
> @@ -103,30 +103,32 @@ static int ls1021_pcie_link_up(struct pcie_port *pp)
>  	return 1;
>  }
>  
> -static void ls1021_pcie_host_init(struct pcie_port *pp)
> +static int ls1021_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct device *dev = pp->dev;
>  	struct ls_pcie *pcie = to_ls_pcie(pp);
>  	u32 index[2];
> +	int ret;
>  
>  	pcie->scfg = syscon_regmap_lookup_by_phandle(dev->of_node,
>  						     "fsl,pcie-scfg");
>  	if (IS_ERR(pcie->scfg)) {
>  		dev_err(dev, "No syscfg phandle specified\n");
> -		pcie->scfg = NULL;
> -		return;
> +		return PTR_ERR(pcie->scfg);
>  	}
>  
> -	if (of_property_read_u32_array(dev->of_node,
> -				       "fsl,pcie-scfg", index, 2)) {
> -		pcie->scfg = NULL;
> -		return;
> -	}
> +	ret = of_property_read_u32_array(dev->of_node,
> +				       "fsl,pcie-scfg", index, 2);
> +	if (ret < 0)
> +		return ret;
> +
>  	pcie->index = index[1];
>  
>  	dw_pcie_setup_rc(pp);
>  
>  	ls_pcie_drop_msg_tlp(pcie);
> +
> +	return 0;
>  }
>  
>  static int ls_pcie_link_up(struct pcie_port *pp)
> @@ -144,7 +146,7 @@ static int ls_pcie_link_up(struct pcie_port *pp)
>  	return 1;
>  }
>  
> -static void ls_pcie_host_init(struct pcie_port *pp)
> +static int ls_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct ls_pcie *pcie = to_ls_pcie(pp);
>  
> @@ -153,6 +155,8 @@ static void ls_pcie_host_init(struct pcie_port *pp)
>  	ls_pcie_clear_multifunction(pcie);
>  	ls_pcie_drop_msg_tlp(pcie);
>  	iowrite32(0, pcie->pp.dbi_base + PCIE_DBI_RO_WR_EN);
> +
> +	return 0;
>  }
>  
>  static int ls_pcie_msi_host_init(struct pcie_port *pp,
> diff --git a/drivers/pci/host/pcie-armada8k.c b/drivers/pci/host/pcie-armada8k.c
> index 0ac0f18..29bdd8b 100644
> --- a/drivers/pci/host/pcie-armada8k.c
> +++ b/drivers/pci/host/pcie-armada8k.c
> @@ -134,12 +134,14 @@ static void armada8k_pcie_establish_link(struct armada8k_pcie *pcie)
>  		dev_err(pp->dev, "Link not up after reconfiguration\n");
>  }
>  
> -static void armada8k_pcie_host_init(struct pcie_port *pp)
> +static int armada8k_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct armada8k_pcie *pcie = to_armada8k_pcie(pp);
>  
>  	dw_pcie_setup_rc(pp);
>  	armada8k_pcie_establish_link(pcie);
> +
> +	return 0;
>  }
>  
>  static irqreturn_t armada8k_pcie_irq_handler(int irq, void *arg)
> diff --git a/drivers/pci/host/pcie-designware-plat.c b/drivers/pci/host/pcie-designware-plat.c
> index 1a02038..e01adbb 100644
> --- a/drivers/pci/host/pcie-designware-plat.c
> +++ b/drivers/pci/host/pcie-designware-plat.c
> @@ -35,13 +35,19 @@ static irqreturn_t dw_plat_pcie_msi_irq_handler(int irq, void *arg)
>  	return dw_handle_msi_irq(pp);
>  }
>  
> -static void dw_plat_pcie_host_init(struct pcie_port *pp)
> +static int dw_plat_pcie_host_init(struct pcie_port *pp)
>  {
> +	int ret;
> +
>  	dw_pcie_setup_rc(pp);
> -	dw_pcie_wait_for_link(pp);
> +	ret = dw_pcie_wait_for_link(pp);
> +	if (ret)
> +		return ret;
>  
>  	if (IS_ENABLED(CONFIG_PCI_MSI))
>  		dw_pcie_msi_init(pp);
> +
> +	return 0;
>  }
>  
>  static struct pcie_host_ops dw_plat_pcie_host_ops = {
> diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
> index bed1999..4a81b72 100644
> --- a/drivers/pci/host/pcie-designware.c
> +++ b/drivers/pci/host/pcie-designware.c
> @@ -638,7 +638,9 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  	}
>  
>  	if (pp->ops->host_init)
> -		pp->ops->host_init(pp);
> +		ret = pp->ops->host_init(pp);
> +			if (ret < 0)
> +				goto error;
>  
>  	pp->root_bus_nr = pp->busn->start;
>  	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
> index a567ea2..eacf18f 100644
> --- a/drivers/pci/host/pcie-designware.h
> +++ b/drivers/pci/host/pcie-designware.h
> @@ -63,7 +63,7 @@ struct pcie_host_ops {
>  	int (*wr_other_conf)(struct pcie_port *pp, struct pci_bus *bus,
>  			unsigned int devfn, int where, int size, u32 val);
>  	int (*link_up)(struct pcie_port *pp);
> -	void (*host_init)(struct pcie_port *pp);
> +	int (*host_init)(struct pcie_port *pp);
>  	void (*msi_set_irq)(struct pcie_port *pp, int irq);
>  	void (*msi_clear_irq)(struct pcie_port *pp, int irq);
>  	phys_addr_t (*get_msi_addr)(struct pcie_port *pp);
> diff --git a/drivers/pci/host/pcie-qcom.c b/drivers/pci/host/pcie-qcom.c
> index 3593640..7d5fb38 100644
> --- a/drivers/pci/host/pcie-qcom.c
> +++ b/drivers/pci/host/pcie-qcom.c
> @@ -429,7 +429,7 @@ static int qcom_pcie_link_up(struct pcie_port *pp)
>  	return !!(val & PCI_EXP_LNKSTA_DLLLA);
>  }
>  
> -static void qcom_pcie_host_init(struct pcie_port *pp)
> +static int qcom_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct qcom_pcie *pcie = to_qcom_pcie(pp);
>  	int ret;
> @@ -455,12 +455,13 @@ static void qcom_pcie_host_init(struct pcie_port *pp)
>  	if (ret)
>  		goto err;
>  
> -	return;
> +	return ret;
>  err:
>  	qcom_ep_reset_assert(pcie);
>  	phy_power_off(pcie->phy);
>  err_deinit:
>  	pcie->ops->deinit(pcie);
> +	return ret;
>  }
>  
>  static int qcom_pcie_rd_own_conf(struct pcie_port *pp, int where, int size,
> diff --git a/drivers/pci/host/pcie-spear13xx.c b/drivers/pci/host/pcie-spear13xx.c
> index 3cf197b..2408f80 100644
> --- a/drivers/pci/host/pcie-spear13xx.c
> +++ b/drivers/pci/host/pcie-spear13xx.c
> @@ -174,12 +174,18 @@ static int spear13xx_pcie_link_up(struct pcie_port *pp)
>  	return 0;
>  }
>  
> -static void spear13xx_pcie_host_init(struct pcie_port *pp)
> +static int spear13xx_pcie_host_init(struct pcie_port *pp)
>  {
>  	struct spear13xx_pcie *spear13xx_pcie = to_spear13xx_pcie(pp);
> +	int ret;
> +
> +	ret = spear13xx_pcie_establish_link(spear13xx_pcie);
> +	if (ret < 0)
> +		return ret;
>  
> -	spear13xx_pcie_establish_link(spear13xx_pcie);
>  	spear13xx_pcie_enable_interrupts(spear13xx_pcie);
> +
> +	return 0;
>  }
>  
>  static struct pcie_host_ops spear13xx_pcie_host_ops = {