Re: [PATCH v3 1/5] PCI: Use an enum for reset type in pci_dev_wait()

[Ilpo Järvinen]

On Fri, 12 Jul 2024, superm1@xxxxxxxxxx wrote:

> From: Mario Limonciello <mario.limonciello@xxxxxxx>
> 
> A string is passed to all callers of pci_dev_wait() which is utilized
> to demonstrate what kind of reset happened when there was a problem.
> 
> This doesn't allow making the behavior for different reset types
> conditional though. Lay some plumbing to allow making comparisons of
> reset types with integers instead. No functional changes.
> 
> Suggested-by: Ilpo Järvinen <ilpo.jarvinen@xxxxxxxxxxxxxxx>
> Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> ---
>  drivers/pci/pci-driver.c |  2 +-
>  drivers/pci/pci.c        | 29 +++++++++++++++++++----------
>  drivers/pci/pci.h        | 11 ++++++++++-
>  drivers/pci/pcie/dpc.c   |  2 +-
>  4 files changed, 31 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
> index af2996d0d17ff..ff97d08741df7 100644
> --- a/drivers/pci/pci-driver.c
> +++ b/drivers/pci/pci-driver.c
> @@ -572,7 +572,7 @@ static void pci_pm_bridge_power_up_actions(struct pci_dev *pci_dev)
>  {
>  	int ret;
>  
> -	ret = pci_bridge_wait_for_secondary_bus(pci_dev, "resume");
> +	ret = pci_bridge_wait_for_secondary_bus(pci_dev, PCI_DEV_WAIT_RESUME);
>  	if (ret) {
>  		/*
>  		 * The downstream link failed to come up, so mark the
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index 35fb1f17a589c..115361a08d9e3 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -181,6 +181,15 @@ static int __init pcie_port_pm_setup(char *str)
>  }
>  __setup("pcie_port_pm=", pcie_port_pm_setup);
>  
> +const char * const pci_reset_types[] = {

Sparse is not happy about this and expects static as it is not defined 
by any header (LKP seems to also have caught this).

> +	"FLR",
> +	"AF_FLR",
> +	"PM D3HOT->D0",
> +	"bus reset",
> +	"resume",
> +	"DPC",

Perhaps the index-based array initialization format would be beneficial 
here.

-- 
 i.

> +};
> +
>  /**
>   * pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
>   * @bus: pointer to PCI bus structure to search
> @@ -1250,7 +1259,7 @@ void pci_resume_bus(struct pci_bus *bus)
>  		pci_walk_bus(bus, pci_resume_one, NULL);
>  }
>  
> -static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
> +static int pci_dev_wait(struct pci_dev *dev, enum pci_reset_type reset_type, int timeout)
>  {
>  	int delay = 1;
>  	bool retrain = false;
> @@ -1288,7 +1297,7 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
>  
>  		if (delay > timeout) {
>  			pci_warn(dev, "not ready %dms after %s; giving up\n",
> -				 delay - 1, reset_type);
> +				 delay - 1, pci_reset_types[reset_type]);
>  			return -ENOTTY;
>  		}
>  
> @@ -1301,7 +1310,7 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
>  				}
>  			}
>  			pci_info(dev, "not ready %dms after %s; waiting\n",
> -				 delay - 1, reset_type);
> +				 delay - 1, pci_reset_types[reset_type]);
>  		}
>  
>  		msleep(delay);
> @@ -1310,10 +1319,10 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
>  
>  	if (delay > PCI_RESET_WAIT)
>  		pci_info(dev, "ready %dms after %s\n", delay - 1,
> -			 reset_type);
> +			 pci_reset_types[reset_type]);
>  	else
>  		pci_dbg(dev, "ready %dms after %s\n", delay - 1,
> -			reset_type);
> +			pci_reset_types[reset_type]);
>  
>  	return 0;
>  }
> @@ -4465,7 +4474,7 @@ int pcie_flr(struct pci_dev *dev)
>  	 */
>  	msleep(100);
>  
> -	return pci_dev_wait(dev, "FLR", PCIE_RESET_READY_POLL_MS);
> +	return pci_dev_wait(dev, PCI_DEV_WAIT_FLR, PCIE_RESET_READY_POLL_MS);
>  }
>  EXPORT_SYMBOL_GPL(pcie_flr);
>  
> @@ -4532,7 +4541,7 @@ static int pci_af_flr(struct pci_dev *dev, bool probe)
>  	 */
>  	msleep(100);
>  
> -	return pci_dev_wait(dev, "AF_FLR", PCIE_RESET_READY_POLL_MS);
> +	return pci_dev_wait(dev, PCI_DEV_WAIT_AF_FLR, PCIE_RESET_READY_POLL_MS);
>  }
>  
>  /**
> @@ -4577,7 +4586,7 @@ static int pci_pm_reset(struct pci_dev *dev, bool probe)
>  	pci_write_config_word(dev, dev->pm_cap + PCI_PM_CTRL, csr);
>  	pci_dev_d3_sleep(dev);
>  
> -	return pci_dev_wait(dev, "PM D3hot->D0", PCIE_RESET_READY_POLL_MS);
> +	return pci_dev_wait(dev, PCI_DEV_WAIT_D3HOT_D0, PCIE_RESET_READY_POLL_MS);
>  }
>  
>  /**
> @@ -4751,7 +4760,7 @@ static int pci_bus_max_d3cold_delay(const struct pci_bus *bus)
>   * Return 0 on success or -ENOTTY if the first device on the secondary bus
>   * failed to become accessible.
>   */
> -int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type)
> +int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, enum pci_reset_type reset_type)
>  {
>  	struct pci_dev *child;
>  	int delay;
> @@ -4885,7 +4894,7 @@ int pci_bridge_secondary_bus_reset(struct pci_dev *dev)
>  {
>  	pcibios_reset_secondary_bus(dev);
>  
> -	return pci_bridge_wait_for_secondary_bus(dev, "bus reset");
> +	return pci_bridge_wait_for_secondary_bus(dev, PCI_DEV_WAIT_BUS_RESET);
>  }
>  EXPORT_SYMBOL_GPL(pci_bridge_secondary_bus_reset);
>  
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index fd44565c47562..88f54d22118dc 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -4,6 +4,15 @@
>  
>  #include <linux/pci.h>
>  
> +enum pci_reset_type {
> +	PCI_DEV_WAIT_FLR,
> +	PCI_DEV_WAIT_AF_FLR,
> +	PCI_DEV_WAIT_D3HOT_D0,
> +	PCI_DEV_WAIT_BUS_RESET,
> +	PCI_DEV_WAIT_RESUME,
> +	PCI_DEV_WAIT_DPC,
> +};
> +
>  /* Number of possible devfns: 0.0 to 1f.7 inclusive */
>  #define MAX_NR_DEVFNS 256
>  
> @@ -94,7 +103,7 @@ void pci_msi_init(struct pci_dev *dev);
>  void pci_msix_init(struct pci_dev *dev);
>  bool pci_bridge_d3_possible(struct pci_dev *dev);
>  void pci_bridge_d3_update(struct pci_dev *dev);
> -int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type);
> +int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, enum pci_reset_type reset_type);
>  
>  static inline void pci_wakeup_event(struct pci_dev *dev)
>  {
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index a668820696dc0..306efc399e503 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -174,7 +174,7 @@ pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
>  	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
>  			      PCI_EXP_DPC_STATUS_TRIGGER);
>  
> -	if (pci_bridge_wait_for_secondary_bus(pdev, "DPC")) {
> +	if (pci_bridge_wait_for_secondary_bus(pdev, PCI_DEV_WAIT_DPC)) {
>  		clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags);
>  		ret = PCI_ERS_RESULT_DISCONNECT;
>  	} else {
>