[PATCH] drivers/misc/cxl: Avoid unnecessary error message

Gavin Shan gwshan at linux.vnet.ibm.com
Wed Feb 8 10:21:30 AEDT 2017

On Tue, Feb 07, 2017 at 10:12:48PM +1100, Michael Ellerman wrote:
>Andrew Donnellan <andrew.donnellan at au1.ibm.com> writes:


>> The effect of this patch is to copy the memory resources from the *real* 
>> PHB to the vPHB, as given through the device tree. It shouldn't have any 
>> practical effect other than squashing this message.
>It sounds a bit backward to me. If we don't need the resources then
>why have them?
>If we have code that thinks that's an error, than maybe that's what
>needs fixing, or special casing for the vPHB?

Yeah, vPHB is a special case. There are basically two stages in PCI enumeration:
probing and then resource assignment. vPHB is different from *real* PHB as the
resource assignment is skipped on it. So vPHB doesn't need any resources to be
populated. However, there is a check in probing stage and it's where the warning
message comes from.


   static void pcibios_setup_phb_resources(struct pci_controller *hose,
                                        struct list_head *resources)
       for (i = 0; i < 3; ++i) {
            res = &hose->mem_resources[i];
            if (!res->flags) {
                if (i == 0)
                    printk(KERN_ERR "PCI: Memory resource 0 not set for "
                        "host bridge %s (domain %d)\n",
                        hose->dn->full_name, hose->global_number);

Alternatively, we can replace prink(KERN_ERR) with pr_debug(). It's going to
affect all PHBs including the real ones. Andrew and Michael, what do you think? :-)


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