From: Dan Williams <dan.j.williams@intel.com>
To: Robert Richter <rrichter@amd.com>,
Alison Schofield <alison.schofield@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
"Ira Weiny" <ira.weiny@intel.com>,
Ben Widawsky <bwidawsk@kernel.org>,
"Dan Williams" <dan.j.williams@intel.com>
Cc: <linux-cxl@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Len Brown <lenb@kernel.org>, Robert Richter <rrichter@amd.com>
Subject: RE: [PATCH 15/15] cxl/acpi: Specify module load order dependency for the cxl_acpi module
Date: Fri, 16 Sep 2022 11:12:27 -0700 [thread overview]
Message-ID: <6324bc8b6c2df_2a6ded2944@dwillia2-xfh.jf.intel.com.notmuch> (raw)
In-Reply-To: <20220831081603.3415-16-rrichter@amd.com>
Robert Richter wrote:
> In RCD mode the CXL mem dev may be detected on the PCI bus before a
> CXL host is brought up. This may cause a CXL mem initialization
> failure as it expects the CXL host already detected.
This is not unique to RCD mode. It is mitigated by the cxl_bus_rescan()
at the completion of cxl_acpi_probe().
> Address this by
> specifying the module dependencies using MODULE_SOFTDEP().
>
> The following additional dependencies exist:
>
> * cxl_mem depends on cxl_acpi: The CXL hosts must be discovered
> before the CXL device is initialized.
>
> * cxl_acpi depends on cxl_port: The acpi driver adds ports to the cxl
> bus, the port driver should be loaded before. This might also work
> if modules are loaded in different order, but a) it aligns with the
> existing cxl_mem/cxl_port softdep and b) it always guarantees a fix
> module load order.
Why does a fixed module load order matter?
>
> Signed-off-by: Robert Richter <rrichter@amd.com>
> ---
> drivers/cxl/acpi.c | 1 +
> drivers/cxl/mem.c | 1 +
> 2 files changed, 2 insertions(+)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 56b2d222afcc..63a1cb295c07 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -834,3 +834,4 @@ module_exit(cxl_host_exit);
> MODULE_LICENSE("GPL v2");
> MODULE_IMPORT_NS(CXL);
> MODULE_IMPORT_NS(ACPI);
> +MODULE_SOFTDEP("pre: cxl_port");
The only reason cxl_acpi would need to preload cxl_port is if it wanted
to do something like:
port = devm_cxl_add_port(...);
if (port->dev.driver)
/* do something with an enabled port */
else
/* do something else if the port failed to enable */
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 64ccf053d32c..ae13ec7d9894 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -128,3 +128,4 @@ MODULE_ALIAS_CXL(CXL_DEVICE_MEMORY_EXPANDER);
> * endpoint registration.
> */
> MODULE_SOFTDEP("pre: cxl_port");
> +MODULE_SOFTDEP("pre: cxl_acpi");
There is no strict requirement that CXL topologies be limited to ACPI
platforms. Per above, the cxl_mem driver will attach when the CXL root
device finally appears, and async out-of-order arrival is ok.
next prev parent reply other threads:[~2022-09-16 18:12 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-31 8:15 [PATCH 00/15] cxl: Add support for Restricted CXL hosts (RCD mode) Robert Richter
2022-08-31 8:15 ` [PATCH 01/15] cxl/core: Remove duplicate declaration of devm_cxl_iomap_block() Robert Richter
2022-08-31 8:54 ` Jonathan Cameron
2022-09-01 5:21 ` Robert Richter
2022-09-07 16:11 ` [PATCH 1/15] " Davidlohr Bueso
2022-09-09 10:38 ` Robert Richter
2022-09-08 5:44 ` [PATCH 01/15] " Dan Williams
2022-09-08 14:51 ` Robert Richter
2022-09-08 19:47 ` Dan Williams
2022-08-31 8:15 ` [PATCH 02/15] cxl/core: Check physical address before mapping it in devm_cxl_iomap_block() Robert Richter
2022-08-31 8:56 ` Jonathan Cameron
2022-09-01 5:31 ` Robert Richter
2022-09-08 5:48 ` Dan Williams
2022-09-09 12:19 ` Robert Richter
2022-09-16 18:04 ` Dan Williams
2022-09-28 10:28 ` Robert Richter
2022-09-30 19:07 ` Dan Williams
2022-08-31 8:15 ` [PATCH 03/15] cxl: Unify debug messages when calling devm_cxl_add_port() Robert Richter
2022-08-31 9:59 ` Jonathan Cameron
2022-09-01 5:36 ` Robert Richter
2022-09-06 7:30 ` Robert Richter
2022-09-06 8:52 ` Jonathan Cameron
2022-09-07 16:21 ` [PATCH 3/15] " Davidlohr Bueso
2022-09-08 5:53 ` [PATCH 03/15] " Dan Williams
2022-09-28 10:32 ` Robert Richter
2022-08-31 8:15 ` [PATCH 04/15] cxl: Unify debug messages when calling devm_cxl_add_dport() Robert Richter
2022-09-07 16:29 ` [PATCH 4/15] " Davidlohr Bueso
2022-09-08 5:55 ` [PATCH 04/15] " Dan Williams
2022-08-31 8:15 ` [PATCH 05/15] cxl/acpi: Add probe function to detect restricted CXL hosts in RCD mode Robert Richter
2022-08-31 10:08 ` Jonathan Cameron
2022-09-01 6:01 ` Robert Richter
2022-09-01 10:10 ` Jonathan Cameron
2022-09-06 7:19 ` Robert Richter
2022-09-06 8:53 ` Jonathan Cameron
2022-09-07 18:22 ` Bjorn Helgaas
2022-09-08 6:00 ` Dan Williams
2022-09-08 6:11 ` Dan Williams
2022-08-31 8:15 ` [PATCH 06/15] PCI/ACPI: Link host bridge to its ACPI fw node Robert Richter
2022-08-31 10:11 ` Jonathan Cameron
2022-09-07 18:37 ` Bjorn Helgaas
2022-09-07 20:15 ` Rafael J. Wysocki
2022-09-08 6:05 ` Dan Williams
2022-09-08 13:06 ` Rafael J. Wysocki
2022-09-08 19:45 ` Dan Williams
2022-09-09 10:20 ` Robert Richter
2022-09-14 22:11 ` Bjorn Helgaas
2022-09-16 23:16 ` Dan Williams
2022-09-08 13:04 ` Rafael J. Wysocki
2022-08-31 8:15 ` [PATCH 07/15] cxl/acpi: Check RCH's PCIe Host Bridge ACPI ID Robert Richter
2022-08-31 10:20 ` Jonathan Cameron
2022-09-01 6:16 ` Robert Richter
2022-09-01 10:14 ` Jonathan Cameron
2022-09-08 6:11 ` Dan Williams
2022-08-31 8:15 ` [PATCH 08/15] cxl/acpi: Check RCH's CXL DVSEC capabilities Robert Richter
2022-08-31 10:52 ` Jonathan Cameron
2022-08-31 11:12 ` Jonathan Cameron
2022-09-01 6:38 ` Robert Richter
2022-09-01 10:37 ` Jonathan Cameron
2022-09-06 10:20 ` Robert Richter
2022-09-01 6:30 ` Robert Richter
2022-09-01 10:23 ` Jonathan Cameron
2022-09-08 6:18 ` Dan Williams
2022-08-31 8:15 ` [PATCH 09/15] cxl/acpi: Determine PCI host bridge's ACPI UID Robert Richter
2022-08-31 11:00 ` Jonathan Cameron
2022-09-01 6:53 ` Robert Richter
2022-09-01 10:41 ` Jonathan Cameron
2022-09-08 6:18 ` Dan Williams
2022-09-08 20:47 ` Jonathan Zhang (Infra)
2022-09-08 21:10 ` Dan Williams
2022-09-08 21:35 ` Jonathan Zhang (Infra)
2022-09-08 22:31 ` Dan Williams
2022-09-08 22:41 ` Jonathan Zhang (Infra)
2022-08-31 8:15 ` [PATCH 10/15] cxl/acpi: Extract the RCH's RCRB base address from CEDT Robert Richter
2022-08-31 11:09 ` Jonathan Cameron
2022-09-01 7:04 ` Robert Richter
2022-08-31 8:15 ` [PATCH 11/15] cxl/acpi: Extract the host's component register base address from RCRB Robert Richter
2022-08-31 11:56 ` Jonathan Cameron
2022-09-01 7:38 ` Robert Richter
2022-09-01 11:00 ` Jonathan Cameron
2022-09-06 11:32 ` Robert Richter
2022-09-08 20:59 ` Jonathan Zhang (Infra)
2022-08-31 8:16 ` [PATCH 12/15] cxl/acpi: Skip devm_cxl_port_enumerate_dports() when in RCD mode Robert Richter
2022-08-31 11:58 ` Jonathan Cameron
2022-09-01 7:40 ` Robert Richter
2022-08-31 8:16 ` [PATCH 13/15] cxl/acpi: Rework devm_cxl_enumerate_ports() to support " Robert Richter
2022-08-31 12:11 ` Jonathan Cameron
2022-09-01 7:50 ` Robert Richter
2022-08-31 8:16 ` [PATCH 14/15] cxl/acpi: Enumerate ports in RCD mode to enable RCHs and RCDs Robert Richter
2022-08-31 12:16 ` Jonathan Cameron
2022-09-01 7:54 ` Robert Richter
2022-08-31 8:16 ` [PATCH 15/15] cxl/acpi: Specify module load order dependency for the cxl_acpi module Robert Richter
2022-09-16 18:12 ` Dan Williams [this message]
2022-08-31 12:23 ` [PATCH 00/15] cxl: Add support for Restricted CXL hosts (RCD mode) Jonathan Cameron
2022-09-01 8:19 ` Robert Richter
2022-09-08 6:41 ` Dan Williams
2022-09-08 5:43 ` Dan Williams
2022-09-08 18:52 ` Jonathan Zhang (Infra)
2022-09-08 19:51 ` Dan Williams
2022-09-08 20:36 ` Jonathan Zhang (Infra)
2022-09-08 21:02 ` Dan Williams
2022-09-16 18:16 ` Dan Williams
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