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PCI: Pull PCI 'latency timer' setup up into the core

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The 'latency timer' of PCI devices, both Type 0 and Type 1,
is setup in architecture-specific code [see: 'pcibios_set_master()'].
There are two approaches being taken by all the architectures - check
if the 'latency timer' is currently set between 16 and 255 and if not
bring it within bounds, or, do nothing (and then there is the
gratuitously different PA-RISC implementation).

There is nothing architecture-specific about PCI's 'latency timer' so
this patch pulls its setup functionality up into the PCI core by
creating a generic 'pcibios_set_master()' function using the '__weak'
attribute which can be used by all architectures as a default which,
if necessary, can then be over-ridden by architecture-specific code.

No functional change.

Signed-off-by: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
This commit is contained in:
Myron Stowe
2011-10-28 15:48:38 -06:00
committed by Jesse Barnes
parent 9cdce18d6f
commit 96c5590058
12 changed files with 32 additions and 45 deletions
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29
drivers/pci/pci.c
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@@ -88,6 +88,12 @@ enum pcie_bus_config_types pcie_bus_config = PCIE_BUS_TUNE_OFF;
u8 pci_dfl_cache_line_size __devinitdata = L1_CACHE_BYTES >> 2;
u8 pci_cache_line_size;
/*
* If we set up a device for bus mastering, we need to check the latency
* timer as certain BIOSes forget to set it properly.
*/
unsigned int pcibios_max_latency = 255;
/**
* pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
* @bus: pointer to PCI bus structure to search
@@ -2595,6 +2601,29 @@ static void __pci_set_master(struct pci_dev *dev, bool enable)
dev->is_busmaster = enable;
}
/**
* pcibios_set_master - enable PCI bus-mastering for device dev
* @dev: the PCI device to enable
*
* Enables PCI bus-mastering for the device. This is the default
* implementation. Architecture specific implementations can override
* this if necessary.
*/
void __weak pcibios_set_master(struct pci_dev *dev)
{
u8 lat;
pci_read_config_byte(dev, PCI_LATENCY_TIMER, &lat);
if (lat < 16)
lat = (64 <= pcibios_max_latency) ? 64 : pcibios_max_latency;
else if (lat > pcibios_max_latency)
lat = pcibios_max_latency;
else
return;
dev_printk(KERN_DEBUG, &dev->dev, "setting latency timer to %d\n", lat);
pci_write_config_byte(dev, PCI_LATENCY_TIMER, lat);
}
/**
* pci_set_master - enables bus-mastering for device dev
* @dev: the PCI device to enable