Messages in this thread | | | Subject | Re: [PATCH v3 2/2] PCI: Add tango PCIe host bridge support | From | Mason <> | Date | Wed, 29 Mar 2017 14:53:47 +0200 |
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On 29/03/2017 14:19, Robin Murphy wrote:
> On 29/03/17 12:34, Marc Gonzalez wrote: > >> + /* >> + * QUIRK #3 >> + * Unfortunately, config and mem spaces are muxed. >> + * Linux does not support such a setting, since drivers are free >> + * to access mem space directly, at any time. >> + * Therefore, we can only PRAY that config and mem space accesses >> + * NEVER occur concurrently. >> + */ > > What about David's suggestion of using an IPI for safe mutual exclusion?
I was left with the impression that this wouldn't solve the problem. If a mem space access is "in flight" on core0 when core1 starts a config space access, an IPI will not prevent breakage.
Did I misunderstand?
For my education, what is the API to send an IPI? And the API to handle an IPI?
>> + if (of_device_is_compatible(dev->of_node, "sigma,smp8759-pcie")) >> + smp8759_init(pcie, base); > > ...then retrieve it with of_device_get_match_data() here. No need to > reinvent the wheel (or have to worry about the ordering of multiple > compatibles once rev. n+1 comes around).
I actually asked about this on IRC. The consensus was "use what best fits your use case". I need to do some processing based on the revision, so I thought
if (chip_x) do_chip_x_init()
was a good way to express my intent. Did I misunderstand?
For example, the init function for rev2 currently looks like this:
static void rev2_init(struct tango_pcie *pcie, void __iomem *base) { void __iomem *misc_irq = base + 0x40; void __iomem *doorbell = base + 0x8c;
pcie->mux = base + 0x2c; pcie->msi_status = base + 0x4c; pcie->msi_mask = base + 0x6c; pcie->msi_doorbell = 0x80000000;
writel(lower_32_bits(pcie->msi_doorbell), doorbell + 0); writel(upper_32_bits(pcie->msi_doorbell), doorbell + 4);
/* Enable legacy PCI interrupts */ writel(BIT(15), misc_irq); writel(0xf << 4, misc_irq + 4); }
>> +#define VENDOR_SIGMA 0x1105 > > Should this not be in include/linux/pci_ids.h?
Doh! Very likely. Thanks.
Regards.
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