[PATCH] platform/x86: dell-smbios: Accumulate supported commands across 0xDA tables

[Rosen Penev <rosenp@gmail.com>]

parse_da_table() runs once for every SMBIOS 0xDA structure and assigns
da_supported_commands from each one, so the last structure wins. Some
systems expose several 0xDA structures where only some fill in
supportedCmds. On a Dell Precision M4800 there are seven: the first six
report 0x40361f5f and the last reports 0, which leaves
da_supported_commands at 0.

As a result dell_smbios_call_filter() rejects every call made through
/dev/wmi/dell-smbios, even token reads from root:

  dell-smbios ...: invalid command, supported commands: 0x       0
  dell-smbios ...: Invalid call 0/0:      5c

and dell_smbios_class_is_supported(CLASS_INFO) returns false, so dell-pc
refuses to load.

OR the field across all 0xDA structures instead. With this change the
token read succeeds and dell-pc registers its cool/quiet/balanced/
performance platform profiles on the M4800.

Fixes: 1f8543a5d602 ("platform/x86: dell-smbios: Add filtering support")
Signed-off-by: Rosen Penev <rosenp@gmail.com>
---
 drivers/platform/x86/dell/dell-smbios-base.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/dell/dell-smbios-base.c b/drivers/platform/x86/dell/dell-smbios-base.c
index c8e93c12c445..f79847f0bfe2 100644
--- a/drivers/platform/x86/dell/dell-smbios-base.c
+++ b/drivers/platform/x86/dell/dell-smbios-base.c
@@ -406,7 +406,12 @@ static void __init parse_da_table(const struct dmi_header *dm)
 	if (dm->length < 17)
 		return;
 
-	da_supported_commands = table->supportedCmds;
+	/*
+	 * Systems may expose several 0xDA structures, and not all of them
+	 * fill in supportedCmds, so accumulate rather than letting the last
+	 * one win.
+	 */
+	da_supported_commands |= table->supportedCmds;
 
 	new_da_tokens = krealloc(da_tokens, (da_num_tokens + tokens) *
 				 sizeof(struct calling_interface_token),
-- 
2.56.1