Re: [RFC PATCH 2/2] PCI: Add basic Compute eXpress Link DVSEC decode
From: Sean V Kelley
Date: Fri May 15 2020 - 18:28:20 EST
Hi,
On 15 May 2020, at 14:04, Bjorn Helgaas wrote:
On Fri, May 15, 2020 at 10:55:28AM -0700, Sean V Kelley wrote:
Compute eXpress Link is a new CPU interconnect created with
workload accelerators in mind. The interconnect relies on PCIe
Electrical
and Physical interconnect for communication. CXL devices enumerate to
the
OS as an ACPI-described PCIe Root Complex Integrated Endpoint.
This patch introduces the bare minimum support by simply looking for
and
caching the DVSEC CXL Extended Capability. Currently, only CXL.io
(which
is mandatory to be configured by BIOS) is enabled. In future, we will
also add support for CXL.cache and CXL.mem.
This looks fine, but AFAICT, it doesn't *do* anything yet (except
print a few things to dmesg). We don't normally merge code until it
adds some new functionality. So just FYI that I'll wait until that
new functionality comes along and then merge this as part of that
series. But let me know if I'm missing something.
Correct. Understood. Iâve additional changes for CXL.mem/.cache.
Iâll queue those up.
+ dev_info(&dev->dev, "CXL: Cache%c IO%c Mem%c Viral%c HDMCount
%d\n",
+ (cap & PCI_CXL_CACHE) ? '+' : '-',
+ (cap & PCI_CXL_IO) ? '+' : '-',
+ (cap & PCI_CXL_MEM) ? '+' : '-',
+ (cap & PCI_CXL_VIRAL) ? '+' : '-',
+ PCI_CXL_HDM_COUNT(cap));
These could use pci_info() and FLAG(), as in pcie_init().
Will do.
+ dev_info(&dev->dev, "CXL: cap ctrl status ctrl2 status2 lock\n");
+ dev_info(&dev->dev, "CXL: %04x %04x %04x %04x %04x %04x\n",
+ cap, ctrl, status, ctrl2, status2, lock);
+}
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -315,6 +315,7 @@ struct pci_dev {
u16 aer_cap; /* AER capability offset */
struct aer_stats *aer_stats; /* AER stats for this device */
#endif
+ u16 cxl_cap; /* CXL capability offset */
Wrap in #ifdef PCI_CXL.
Will do.
Thanks,
Sean