• Sam Bobroff's avatar
    powerpc/64: Adjust order in pcibios_init() · 3f068aae
    Sam Bobroff authored
    The pcibios_init() function for PowerPC 64 currently calls
    pci_bus_add_devices() before pcibios_resource_survey(). This means
    that at boot time, when the pcibios_bus_add_device() hooks are called
    by pci_bus_add_devices(), device resources have not been allocated and
    they are unable to perform EEH setup, so a separate pass is needed.
    
    This patch adjusts that order so that it will become possible to
    consolidate the EEH setup work into a single location.
    
    The only functional change is to execute pcibios_resource_survey()
    (excepting ppc_md.pcibios_fixup(), see below) before
    pci_bus_add_devices() instead of after it.
    
    Because pcibios_scan_phb() and pci_bus_add_devices() are called
    together in a loop, this must be broken into one loop for each call.
    Then the call to pcibios_resource_survey() is moved up in between
    them. This changes the ordering but because pcibios_resource_survey()
    also calls ppc_md.pcibios_fixup(), that call is extracted out into
    pcibios_init() to where pcibios_resource_survey() was, so that it is
    not moved.
    
    The only other caller of pcibios_resource_survey() is the PowerPC 32
    version of pcibios_init(), and therefore, that is modified to call
    ppc_md.pcibios_fixup() right after pcibios_resource_survey() so that
    there is no functional change there at all.
    
    The re-arrangement will cause very few side-effects because at this
    stage in the boot, pci_bus_add_devices() does very little:
    - pci_create_sysfs_dev_files() does nothing (no sysfs yet)
    - pci_proc_attach_device() does nothing (no proc yet)
    - device_attach() does nothing (no drivers yet)
    This leaves only the pci_final_fixup calls, D3 support, and marking
    the device as added. Of those, only the pci_final_fixup calls have the
    potential to be affected by resource allocation.
    
    The only pci_final_fixup handlers that touch resources seem to be one
    for x86 (pci_amd_enable_64bit_bar()), and a PowerPC 32 platform driver
    (quirk_final_uli1575()), neither of which use this pcibios_init()
    function. Even if they did, it would almost certainly be a bug, under
    the current ordering, to rely on or make changes to resources before
    they were allocated.
    Signed-off-by: default avatarSam Bobroff <sbobroff@linux.ibm.com>
    Reviewed-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Link: https://lore.kernel.org/r/4506b0489eabd0921a3587d90bd44c7683f3472d.1565930772.git.sbobroff@linux.ibm.com
    3f068aae
pci_64.c 7.22 KB