Re: [PATCH] hwmon, k10temp: Add support for AMD F15h M60h processor

From: Guenter Roeck
Date: Tue Jul 15 2014 - 05:03:33 EST

On 07/15/2014 12:41 AM, Clemens Ladisch wrote:
Guenter Roeck wrote:
On Mon, Jul 14, 2014 at 10:21:51PM +0200, Clemens Ladisch wrote:
Borislav Petkov wrote:
On Mon, Jul 14, 2014 at 03:23:08PM -0500, Aravind Gopalakrishnan wrote:
+ if (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model == 0x60) {
+ pci_bus_write_config_dword(pdev->bus, PCI_DEVFN(0, 0),
+ NB_SMU_IND_ADDR, IND_ADDR_OFFSET);
+ pci_bus_read_config_dword(pdev->bus, PCI_DEVFN(0, 0),
+ NB_SMU_IND_DATA, &regval);

How do you prevent races with any other code that accesses some indirect
register?

I just wanted to ask exactly the same question. I think this will need
locking.

If there actually is any other code; these indirect SMU registers appear
to be mostly undocumented and to be intended to be used by the BIOS.
(Which makes me wonder why the temperature sensor was moved there.)

Scary. Does that mean there is a chance they may get used through ACPI ?

Anyway, if a lock is needed, it looks as if it could go into a helper
function such as "amd_nb_smu_ind_read()" in arch/x86/kernel/amd_nb.c.

Yes, something like that.

Guenter

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