Subject: Re: [PATCH] PCI: designware: bail out if host_init failed

From: Jisheng Zhang <[email-masked]>
Date: Tue, 8 Dec 2015 13:58:43 +0800

Dear Bjorn,

On Wed, 25 Nov 2015 14:01:03 -0600
Bjorn Helgaas wrote:

> Hi Jisheng,
> 
> On Thu, Nov 12, 2015 at 09:48:45PM +0800, Jisheng Zhang wrote:
> > There's no reason to continue the initialization such as configure
> > register, scan root bus etc. if customized host_init() failed. This
> > patch tries to check the host_init result, bail out if failed.  
> 
> This patch changes the (*host_init) return type and adds "return 0" to
> the host_init() implementations of ten different drivers, all to
> support a possible error in one driver.
> 
> Is there any way to detect and handle the error in
> ls1021_pcie_host_init() earlier, maybe by doing the syscon_regmap
> lookup in ls_pcie_probe() instead of in the host_init() function?
> 
> That would be even better because you wouldn't have to touch any of
> the other drivers, and you'd detect the error even earlier, before
> we've done any of the designware setup.

Sorry for being late. Got your point. The reason I made this patch is that:
I want to clk gate the pcie host to save power if the customized host_init()
report link training failure etc. For example: there's no pcie device in the
slot at all. But today, I have a different idea: the PCIE support hotplug,
so link training failure doesn't mean we should bail out, in fact we should
continue the initialization as current code does. So I think Jingoo made the
correct decision when implement the pcie designware interface. I want to drop
this patch.

Only one problem need your suggestions: how to save power when there's no device
, I.E clk gate the host, shutdown the pcie phy etc.

Any suggestions are appreciated!

Thanks in advance,
Jisheng

> 
> Bjorn
> 
> > Signed-off-by: Jisheng Zhang <[email-masked]>
> > ---
> >  drivers/pci/host/pci-dra7xx.c      |  4 +++-
> >  drivers/pci/host/pci-exynos.c      |  4 +++-
> >  drivers/pci/host/pci-imx6.c        |  4 +++-
> >  drivers/pci/host/pci-keystone.c    |  4 +++-
> >  drivers/pci/host/pci-layerscape.c  | 25 ++++++++++++++++---------
> >  drivers/pci/host/pcie-designware.c |  7 +++++--
> >  drivers/pci/host/pcie-designware.h |  2 +-
> >  drivers/pci/host/pcie-spear13xx.c  |  4 +++-
> >  8 files changed, 37 insertions(+), 17 deletions(-)
> > 
> > diff --git a/drivers/pci/host/pci-dra7xx.c b/drivers/pci/host/pci-dra7xx.c
> > index 8c36880..b3160a1 100644
> > --- a/drivers/pci/host/pci-dra7xx.c
> > +++ b/drivers/pci/host/pci-dra7xx.c
> > @@ -149,7 +149,7 @@ static void dra7xx_pcie_enable_interrupts(struct pcie_port *pp)
> >  				   LEG_EP_INTERRUPTS);
> >  }
> >  
> > -static void dra7xx_pcie_host_init(struct pcie_port *pp)
> > +static int dra7xx_pcie_host_init(struct pcie_port *pp)
> >  {
> >  	dw_pcie_setup_rc(pp);
> >  
> > @@ -162,6 +162,8 @@ static void dra7xx_pcie_host_init(struct pcie_port *pp)
> >  	if (IS_ENABLED(CONFIG_PCI_MSI))
> >  		dw_pcie_msi_init(pp);
> >  	dra7xx_pcie_enable_interrupts(pp);
> > +
> > +	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 01095e1..57f370b 100644
> > --- a/drivers/pci/host/pci-exynos.c
> > +++ b/drivers/pci/host/pci-exynos.c
> > @@ -481,10 +481,12 @@ 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)
> >  {
> >  	exynos_pcie_establish_link(pp);
> >  	exynos_pcie_enable_interrupts(pp);
> > +
> > +	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 22e8224..9a46680 100644
> > --- a/drivers/pci/host/pci-imx6.c
> > +++ b/drivers/pci/host/pci-imx6.c
> > @@ -425,7 +425,7 @@ static int imx6_pcie_establish_link(struct pcie_port *pp)
> >  	return 0;
> >  }
> >  
> > -static void imx6_pcie_host_init(struct pcie_port *pp)
> > +static int imx6_pcie_host_init(struct pcie_port *pp)
> >  {
> >  	imx6_pcie_assert_core_reset(pp);
> >  
> > @@ -439,6 +439,8 @@ static void imx6_pcie_host_init(struct pcie_port *pp)
> >  
> >  	if (IS_ENABLED(CONFIG_PCI_MSI))
> >  		dw_pcie_msi_init(pp);
> > +
> > +	return 0;
> >  }
> >  
> >  static void imx6_pcie_reset_phy(struct pcie_port *pp)
> > diff --git a/drivers/pci/host/pci-keystone.c b/drivers/pci/host/pci-keystone.c
> > index 0aa81bd..2604571 100644
> > --- a/drivers/pci/host/pci-keystone.c
> > +++ b/drivers/pci/host/pci-keystone.c
> > @@ -250,7 +250,7 @@ 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;
> > @@ -277,6 +277,8 @@ 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 3923bed..a6e9070 100644
> > --- a/drivers/pci/host/pci-layerscape.c
> > +++ b/drivers/pci/host/pci-layerscape.c
> > @@ -94,8 +94,9 @@ 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)
> >  {
> > +	int ret;
> >  	struct ls_pcie *pcie = to_ls_pcie(pp);
> >  	u32 val, index[2];
> >  
> > @@ -103,15 +104,14 @@ static void ls1021_pcie_host_init(struct pcie_port *pp)
> >  						     "fsl,pcie-scfg");
> >  	if (IS_ERR(pcie->scfg)) {
> >  		dev_err(pp->dev, "No syscfg phandle specified\n");
> > -		pcie->scfg = NULL;
> > -		return;
> > +		ret = PTR_ERR(pcie->scfg);
> > +		goto err;
> >  	}
> >  
> > -	if (of_property_read_u32_array(pp->dev->of_node,
> > -				       "fsl,pcie-scfg", index, 2)) {
> > -		pcie->scfg = NULL;
> > -		return;
> > -	}
> > +	ret = of_property_read_u32_array(pp->dev->of_node,
> > +					 "fsl,pcie-scfg", index, 2);
> > +	if (ret)
> > +		goto err;
> >  	pcie->index = index[1];
> >  
> >  	dw_pcie_setup_rc(pp);
> > @@ -123,6 +123,11 @@ static void ls1021_pcie_host_init(struct pcie_port *pp)
> >  	val = ioread32(pcie->dbi + PCIE_STRFMR1);
> >  	val &= 0xffff;
> >  	iowrite32(val, pcie->dbi + PCIE_STRFMR1);
> > +
> > +	return 0;
> > +err:
> > +	pcie->scfg = NULL;
> > +	return ret;
> >  }
> >  
> >  static int ls_pcie_link_up(struct pcie_port *pp)
> > @@ -140,7 +145,7 @@ 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);
> >  
> > @@ -148,6 +153,8 @@ static void ls_pcie_host_init(struct pcie_port *pp)
> >  	ls_pcie_fix_class(pcie);
> >  	ls_pcie_clear_multifunction(pcie);
> >  	iowrite32(0, pcie->dbi + 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-designware.c b/drivers/pci/host/pcie-designware.c
> > index 540f077..a80a9ba 100644
> > --- a/drivers/pci/host/pcie-designware.c
> > +++ b/drivers/pci/host/pcie-designware.c
> > @@ -515,8 +515,11 @@ int dw_pcie_host_init(struct pcie_port *pp)
> >  		}
> >  	}
> >  
> > -	if (pp->ops->host_init)
> > -		pp->ops->host_init(pp);
> > +	if (pp->ops->host_init) {
> > +		ret = pp->ops->host_init(pp);
> > +		if (ret)
> > +			return ret;
> > +	}
> >  
> >  	if (!pp->ops->rd_other_conf)
> >  		dw_pcie_prog_outbound_atu(pp, PCIE_ATU_REGION_INDEX1,
> > diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
> > index 2356d29..7b5317f 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-spear13xx.c b/drivers/pci/host/pcie-spear13xx.c
> > index b95b756..50b3b31 100644
> > --- a/drivers/pci/host/pcie-spear13xx.c
> > +++ b/drivers/pci/host/pcie-spear13xx.c
> > @@ -256,10 +256,12 @@ 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)
> >  {
> >  	spear13xx_pcie_establish_link(pp);
> >  	spear13xx_pcie_enable_interrupts(pp);
> > +
> > +	return 0;
> >  }
> >  
> >  static struct pcie_host_ops spear13xx_pcie_host_ops = {
> > -- 
> > 2.6.2
> > 
> > --
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