linux-kernel - Re: [PATCH 1/2] powerpc/pci: Allow to disable filling deprecated pci-OF-bus-map

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Date:   Sun, 9 Oct 2022 13:25:55 +0200
From:   Pali Rohár <pali@...nel.org>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] powerpc/pci: Allow to disable filling deprecated
 pci-OF-bus-map

Hello! Any comments on this? It would be nice to take these two patches
(or at least patch 2) to finally enable PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
by default where possible.

Per following comment there can be an issue with early powermac so seems
that PPC_PCI_OF_BUS_MAP_FILL still has to be by default enabled (which
implies that PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT is disabled) on powermac:
https://lore.kernel.org/linuxppc-dev/575f239205e8635add81c9f902b7d9db7beb83ea.camel@kernel.crashing.org/

On Wednesday 17 August 2022 18:39:26 Pali Rohár wrote:
> Creating or filling pci-OF-bus-map property in the device-tree is
> deprecated since May 2006 [1]. Allow to disable filling this property by
> unsetting config option CONFIG_PPC_PCI_OF_BUS_MAP_FILL for remaining chrp
> and powermac code.
> 
> Disabling of pci-OF-bus-map property allows to enable new option
> CONFIG_PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT also for chrp and powermac.
> 
> [1] - https://lore.kernel.org/linuxppc-dev/1148016268.13249.14.camel@localhost.localdomain/
> 
> Signed-off-by: Pali Rohár <pali@...nel.org>
> ---
>  arch/powerpc/Kconfig         | 12 +++++++++++-
>  arch/powerpc/kernel/pci_32.c |  6 ++++++
>  2 files changed, 17 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 5881441f7672..df2696c406ad 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -373,9 +373,19 @@ config PPC_DCR
>  	depends on PPC_DCR_NATIVE || PPC_DCR_MMIO
>  	default y
>  
> +config PPC_PCI_OF_BUS_MAP_FILL
> +	bool "Fill pci-OF-bus-map property in the device-tree"
> +	depends on PPC32
> +	depends on PPC_PMAC || PPC_CHRP
> +	default y
> +	help
> +	  This option creates and fills pci-OF-bus-map property in the
> +	  device-tree which is deprecated and is needed only for old
> +	  platforms.
> +
>  config PPC_PCI_BUS_NUM_DOMAIN_DEPENDENT
>  	depends on PPC32
> -	depends on !PPC_PMAC && !PPC_CHRP
> +	depends on !PPC_PCI_OF_BUS_MAP_FILL
>  	bool "Assign PCI bus numbers from zero individually for each PCI domain"
>  	help
>  	  By default on PPC32 were PCI bus numbers unique across all PCI domains.
> diff --git a/arch/powerpc/kernel/pci_32.c b/arch/powerpc/kernel/pci_32.c
> index 433965bf37b4..ffc4e1928c80 100644
> --- a/arch/powerpc/kernel/pci_32.c
> +++ b/arch/powerpc/kernel/pci_32.c
> @@ -64,6 +64,8 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_IBM,	PCI_DEVICE_ID_IBM_CPC710_PCI64,	fixu
>  
>  #if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP)
>  
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP_FILL
> +
>  static u8* pci_to_OF_bus_map;
>  static int pci_bus_count;
>  
> @@ -223,6 +225,8 @@ pci_create_OF_bus_map(void)
>  }
>  #endif
>  
> +#endif /* CONFIG_PPC_PCI_OF_BUS_MAP_FILL */
> +
>  #endif /* defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP) */
>  
>  void pcibios_setup_phb_io_space(struct pci_controller *hose)
> @@ -264,6 +268,7 @@ static int __init pcibios_init(void)
>  	}
>  
>  #if defined(CONFIG_PPC_PMAC) || defined(CONFIG_PPC_CHRP)
> +#ifdef CONFIG_PPC_PCI_OF_BUS_MAP_FILL
>  	pci_bus_count = next_busno;
>  
>  	/* OpenFirmware based machines need a map of OF bus
> @@ -272,6 +277,7 @@ static int __init pcibios_init(void)
>  	 */
>  	if (pci_assign_all_buses)
>  		pcibios_make_OF_bus_map();
> +#endif
>  #endif
>  
>  	/* Call common code to handle resource allocation */
> -- 
> 2.20.1
>