[S] Change in coreboot[master]: device/pciexp_device.c: Do not enable common clock if already active

[Subrata Banik (Code Review)]

Attention is currently required from: Paul Menzel, Werner Zeh.

Subrata Banik has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/73310 )

Change subject: device/pciexp_device.c: Do not enable common clock if already active
......................................................................

Patch Set 1:

(1 comment)

File src/device/pciexp_device.c:

https://review.coreboot.org/c/coreboot/+/73310/comment/9aae5065_f4c96763 
PS1, Line 205: 		printk(BIOS_INFO, "Common Clock Configuration already enabled\n");
> Hey Subrata, any response to my question from your side?

Yeah, something like below code ?

WDYT?

```
static bool is_ccc_enabled(struct device *root, unsigned int root_cap,
    			struct device *endp, unsigned int endp_cap)
{
   uint16_t root_ccc, endp_ccc;

/* No need to enable common clock if it is already active. */
    root_ccc = pci_read_config16(root, root_cap + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_CCC;
    endp_ccc = pci_read_config16(endp, endp_cap + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_CCC;
    if (root_ccc && endp_ccc) {
    	printk(BIOS_INFO, "Common Clock Configuration already enabled\n");
    	return true;
    }
    return false;
}
```

```
static void pciexp_enable_common_clock(struct device *root, unsigned int root_cap,
    			       struct device *endp, unsigned int endp_cap)
{
     if (is_ccc_enabled(....))
         return;
     ....
}
```