Hi Yinghai,
How about following patch to solve the "probe/free then install" issue?
For pci_mmcfg_early_init(), we still need the "probe/free then install" dance
because MMCONFIG may be need for hardware quirks at early stage.
For pci_mmcfg_late_init(), the patch get rid of the redundant "probe/free"
steps. It also generates better readable code.
Thanks!
Gerry
---
The logic of __pci_mmcfg_init() is a little complex, so simplify it a little.
Signed-off-by: Jiang Liu <liuj97@xxxxxxxxx>
---
arch/x86/pci/mmconfig-shared.c | 72 ++++++++++++++++++++++------------------
1 files changed, 40 insertions(+), 32 deletions(-)
diff --git a/arch/x86/pci/mmconfig-shared.c b/arch/x86/pci/mmconfig-shared.c
index 06da933..e9a791c 100644
--- a/arch/x86/pci/mmconfig-shared.c
+++ b/arch/x86/pci/mmconfig-shared.c
@@ -566,8 +566,6 @@ static void __init pci_mmcfg_reject_broken(int early)
}
}
-static int __initdata known_bridge;
-
static int __init acpi_mcfg_check_entry(struct acpi_table_mcfg *mcfg,
struct acpi_mcfg_allocation *cfg)
{
@@ -647,25 +645,10 @@ static int __init pci_parse_mcfg(struct acpi_table_header *header)
return 0;
}
-static void __init __pci_mmcfg_init(int early)
-{
- /* MMCONFIG disabled */
- if ((pci_probe & PCI_PROBE_MMCONF) == 0)
- return;
-
- /* for late to exit */
- if (known_bridge)
- return;
-
- /* MMCONFIG already enabled */
- if (!early && !(pci_probe & PCI_PROBE_MASK & ~PCI_PROBE_MMCONF))
- goto out;
-
- if (early) {
- if (pci_mmcfg_check_hostbridge())
- known_bridge = 1;
- }
+static int __initdata known_bridge;
+static void __init __pci_mmcfg_init(int early, bool create_on_demand)
+{
if (!known_bridge)
acpi_sfi_table_parse(ACPI_SIG_MCFG, pci_parse_mcfg);
@@ -684,6 +667,13 @@ static void __init __pci_mmcfg_init(int early)
}
}
+ /*
+ * Avoid redundant pci_mmcfg_arch_map()/pci_mmcfg_arch_unmap() calls
+ * for each MMCONFIG entry if they will be created on demand.
+ */
+ if (create_on_demand)
+ free_all_mmcfg();
+
if (pci_mmcfg_arch_init())
pci_probe = (pci_probe & ~PCI_PROBE_MASK) | PCI_PROBE_MMCONF;
else {
@@ -694,26 +684,44 @@ static void __init __pci_mmcfg_init(int early)
pci_mmcfg_resources_inserted = 1;
pci_mmcfg_arch_init_failed = true;
}
-
-out:
- /*
- * Free all MCFG entries if ACPI is enabled. MCFG information will
- * be added back on demand by the pci_root driver later.
- */
- if (!early && !acpi_disabled && !known_bridge &&
- !pci_mmcfg_arch_init_failed)
- if (!acpi_pci_cache_mcfg())
- free_all_mmcfg();
}
void __init pci_mmcfg_early_init(void)
{
- __pci_mmcfg_init(1);
+ if (pci_probe & PCI_PROBE_MMCONF) {
+ if (pci_mmcfg_check_hostbridge())
+ known_bridge = 1;
+ __pci_mmcfg_init(1, false);
+ }
}
void __init pci_mmcfg_late_init(void)
{
- __pci_mmcfg_init(0);
+ bool create_on_demand;
+
+ /* MMCONFIG disabled */
+ if ((pci_probe & PCI_PROBE_MMCONF) == 0)
+ return;
+
+ /* Don't touch hardcoded MMCONFIG information */
+ if (known_bridge)
+ return;
+
+ /*
+ * MMCONFIG information will be created on demand by pci_root driver
+ * when binding to ACPI host bridge deivces.
+ */
+ create_on_demand = (!acpi_disabled && !acpi_pci_cache_mcfg());
+
+ /* pci_mmcfg_early_init() fails to setup MMCONFIG, try again. */
+ if (pci_probe & PCI_PROBE_MASK & ~PCI_PROBE_MMCONF)
+ __pci_mmcfg_init(0, create_on_demand);
+ /*
+ * Free MMCONFIG information created by pci_mmcfg_early_init()
+ * if MMCONFIG information will be created on demand.
+ */
+ else if (create_on_demand)
+ free_all_mmcfg();
}
static int __init pci_mmcfg_late_insert_resources(void)
--
1.7.1
On 2012-6-16 0:55, Yinghai Lu wrote:
> On Fri, Jun 15, 2012 at 8:46 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
>>
>>> But the code in the init path is ridiculously, embarrassingly complicated ...
>>
>> I rest my case. The current init path is unmaintainable.
>>
>> I'll wait for a v8 (or later) with fixes for the build issues
>> Fengguang found and Yinghai's ack. It will make things somewhat
>> easier for me if you start with my topic/jiang-mmconfig-v7 branch.
>
> yes. probe/free then install is not good.
>
> should make __pci_mmcfg_init() to cache needed stuff for all path, and
> then consume stored
> entry just before scan root bus.
>
> Thanks
>
> Yinghai
>
>
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