Messages in this thread | | | Date | Thu, 9 Feb 2023 09:07:18 -0800 | From | Dan Williams <> | Subject | RE: [PATCH] cxl/port: Disable decoder setup for endpoints in RCD mode |
| |
Robert Richter wrote: > In RCD mode the HDM decoder capability is optional for endpoints and > may not exist. The HDM range registers are used instead. Since the > driver relies on the existence of an HDM decoder capability, its > absence will cause the initialization of a memory card to fail. > > Moreover, the driver also tries to enable or reuse enabled memory > ranges. In the worst case this may lead to a system hang due to > disabling system memory that was previously provided and setup by > system firmware. > > To solve the issues described, disable decoder setup for RCD endpoints > and instead rely exclusively on system firmware to enable those memory > ranges. Decoders are used by the kernel to setup and configure CXL > memory regions, esp. to enable and disable them. Since Hot-plug is not > supported for devices in RCD mode, the ability to disable that memory > by the kernel using a decoder is not a necessarily requirement, > decoders are not needed then. > > Fixes: 34e37b4c432c ("cxl/port: Enable HDM Capability after validating DVSEC Ranges") > Signed-off-by: Robert Richter <rrichter@amd.com>
Does Dave's series address this problem?
https://lore.kernel.org/linux-cxl/167588394236.1155956.8466475582138210344.stgit@djiang5-mobl3.local/
...that is arranging for the driver to carry-on in the absence of the HDM Decoder Capability.
| |