linux-kernel - Re: [PATCH 2/2] PCI: Use an error code with PCIe failed link retraining

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Message-ID: <855a5a56-75f2-2ce5-7f35-b761b62784e7@linux.intel.com>
Date: Mon, 12 Feb 2024 14:11:32 +0200 (EET)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: "Maciej W. Rozycki" <macro@...am.me.uk>
cc: Bjorn Helgaas <bhelgaas@...gle.com>, 
    Mika Westerberg <mika.westerberg@...ux.intel.com>, 
    linux-pci@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] PCI: Use an error code with PCIe failed link
 retraining

On Sat, 10 Feb 2024, Maciej W. Rozycki wrote:

> Given how the call place in `pcie_wait_for_link_delay' got structured 
> now, and that `pcie_retrain_link' returns a potentially useful error 
> code, convert `pcie_failed_link_retrain' to return an error code rather 
> than a boolean status, fixing handling at the call site mentioned.  
> Update the other call site accordingly.
> 
> Fixes: 1abb47390350 ("Merge branch 'pci/enumeration'")
> Reported-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
> Link: https://lore.kernel.org/r/aa2d1c4e-9961-d54a-00c7-ddf8e858a9b0@linux.intel.com/
> Signed-off-by: Maciej W. Rozycki <macro@...am.me.uk>
> Cc: stable@...r.kernel.org # v6.5+
> ---
>  drivers/pci/pci.c    |    2 +-
>  drivers/pci/pci.h    |    6 +++---
>  drivers/pci/quirks.c |   14 +++++++-------
>  3 files changed, 11 insertions(+), 11 deletions(-)
> 
> linux-pcie-failed-link-retrain-status-int.diff
> Index: linux-macro/drivers/pci/pci.c
> ===================================================================
> --- linux-macro.orig/drivers/pci/pci.c
> +++ linux-macro/drivers/pci/pci.c
> @@ -1263,7 +1263,7 @@ static int pci_dev_wait(struct pci_dev *
>  		if (delay > PCI_RESET_WAIT) {
>  			if (retrain) {
>  				retrain = false;
> -				if (pcie_failed_link_retrain(bridge)) {
> +				if (pcie_failed_link_retrain(bridge) == 0) {
>  					delay = 1;
>  					continue;
>  				}
> Index: linux-macro/drivers/pci/pci.h
> ===================================================================
> --- linux-macro.orig/drivers/pci/pci.h
> +++ linux-macro/drivers/pci/pci.h
> @@ -540,7 +540,7 @@ void pci_acs_init(struct pci_dev *dev);
>  int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags);
>  int pci_dev_specific_enable_acs(struct pci_dev *dev);
>  int pci_dev_specific_disable_acs_redir(struct pci_dev *dev);
> -bool pcie_failed_link_retrain(struct pci_dev *dev);
> +int pcie_failed_link_retrain(struct pci_dev *dev);
>  #else
>  static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev,
>  					       u16 acs_flags)
> @@ -555,9 +555,9 @@ static inline int pci_dev_specific_disab
>  {
>  	return -ENOTTY;
>  }
> -static inline bool pcie_failed_link_retrain(struct pci_dev *dev)
> +static inline int pcie_failed_link_retrain(struct pci_dev *dev)
>  {
> -	return false;
> +	return -ENOTTY;
>  }
>  #endif
>  
> Index: linux-macro/drivers/pci/quirks.c
> ===================================================================
> --- linux-macro.orig/drivers/pci/quirks.c
> +++ linux-macro/drivers/pci/quirks.c
> @@ -74,17 +74,17 @@
>   * firmware may have already arranged and lift it with ports that already
>   * report their data link being up.
>   *
> - * Return TRUE if the link has been successfully retrained, otherwise FALSE,
> + * Return 0 if the link has been successfully retrained, otherwise an error,
>   * also when retraining was not needed in the first place.
>   */
> -bool pcie_failed_link_retrain(struct pci_dev *dev)
> +int pcie_failed_link_retrain(struct pci_dev *dev)
>  {
>  	static const struct pci_device_id ids[] = {
>  		{ PCI_VDEVICE(ASMEDIA, 0x2824) }, /* ASMedia ASM2824 */
>  		{}
>  	};
>  	u16 lnksta, lnkctl2;
> -	bool ret = false;
> +	int ret = -ENOTTY;
>  
>  	if (!pci_is_pcie(dev) || !pcie_downstream_port(dev) ||
>  	    !pcie_cap_has_lnkctl2(dev) || !dev->link_active_reporting)
> @@ -100,8 +100,8 @@ bool pcie_failed_link_retrain(struct pci
>  		lnkctl2 |= PCI_EXP_LNKCTL2_TLS_2_5GT;
>  		pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
>  
> -		ret = pcie_retrain_link(dev, false) == 0;
> -		if (!ret) {
> +		ret = pcie_retrain_link(dev, false);
> +		if (ret) {
>  			pci_info(dev, "retraining failed\n");
>  			return ret;
>  		}
> @@ -120,8 +120,8 @@ bool pcie_failed_link_retrain(struct pci
>  		lnkctl2 |= lnkcap & PCI_EXP_LNKCAP_SLS;
>  		pcie_capability_write_word(dev, PCI_EXP_LNKCTL2, lnkctl2);
>  
> -		ret = pcie_retrain_link(dev, false) == 0;
> -		if (!ret) {
> +		ret = pcie_retrain_link(dev, false);
> +		if (ret) {
>  			pci_info(dev, "retraining failed\n");
>  			return ret;
>  		}

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

I closed my patch from patchwork that is not need after this change.

-- 
 i.