From 08258881ed56e008366c9c242cd0e6ba14123de6 Mon Sep 17 00:00:00 2001 From: Matt Delco Date: Wed, 30 Jan 2019 11:16:08 -0800 Subject: acpi: device: avoid empty property list in acpi_dp_write If an acpi_dp table has children but no properties then acpi_dp_write() will write out a properties UUID and package that contains no properties. The existing function will avoid writing out a UUID and empty package when no children exist, but it seems to assume that properties will always be used. With this change properties are handled in a manner akin to children so that a UUID and package are only written if properties exist. BUG=none BRANCH=none TEST=Confirmed that prior to this change a UUID and empty package was present for a device that had children but no properties. Verified that after this change the UUID and empty package are no longer present but the child UUID and package are still present. Change-Id: I6f5597713a1e91ca26b409f36b3ff9eb90a010af Signed-off-by: Matt Delco Reviewed-on: https://review.coreboot.org/c/31161 Tested-by: build bot (Jenkins) Reviewed-by: Duncan Laurie Reviewed-by: Furquan Shaikh --- src/arch/x86/acpi_device.c | 42 ++++++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 16 deletions(-) (limited to 'src/arch') diff --git a/src/arch/x86/acpi_device.c b/src/arch/x86/acpi_device.c index 48b7fee26c23..c62d6f3688ff 100644 --- a/src/arch/x86/acpi_device.c +++ b/src/arch/x86/acpi_device.c @@ -632,7 +632,7 @@ static void acpi_dp_free(struct acpi_dp *dp) void acpi_dp_write(struct acpi_dp *table) { struct acpi_dp *dp, *prop; - char *dp_count, *prop_count; + char *dp_count, *prop_count = NULL; int child_count = 0; if (!table || table->type != ACPI_DP_TYPE_TABLE) @@ -644,32 +644,42 @@ void acpi_dp_write(struct acpi_dp *table) /* Device Property list starts with the next entry */ prop = table->next; - /* Package (DP), default to 2 elements (assuming no children) */ - dp_count = acpigen_write_package(2); - - /* ToUUID (ACPI_DP_UUID) */ - acpigen_write_uuid(ACPI_DP_UUID); - - /* Package (PROP), element count determined as it is populated */ - prop_count = acpigen_write_package(0); + /* Package (DP), default to assuming no properties or children */ + dp_count = acpigen_write_package(0); /* Print base properties */ for (dp = prop; dp; dp = dp->next) { if (dp->type == ACPI_DP_TYPE_CHILD) { child_count++; } else { + /* + * The UUID and package is only added when + * we come across the first property. This + * is to avoid creating a zero-length package + * in situations where there are only children. + */ + if (!prop_count) { + *dp_count += 2; + /* ToUUID (ACPI_DP_UUID) */ + acpigen_write_uuid(ACPI_DP_UUID); + /* + * Package (PROP), element count determined as + * it is populated + */ + prop_count = acpigen_write_package(0); + } (*prop_count)++; acpi_dp_write_property(dp); } } - - /* Package (PROP) length */ - acpigen_pop_len(); + if (prop_count) { + /* Package (PROP) length, if a package was written */ + acpigen_pop_len(); + } if (child_count) { - /* Update DP package count to 4 */ - *dp_count = 4; - + /* Update DP package count to 2 or 4 */ + *dp_count += 2; /* ToUUID (ACPI_DP_CHILD_UUID) */ acpigen_write_uuid(ACPI_DP_CHILD_UUID); @@ -679,7 +689,7 @@ void acpi_dp_write(struct acpi_dp *table) for (dp = prop; dp; dp = dp->next) if (dp->type == ACPI_DP_TYPE_CHILD) acpi_dp_write_property(dp); - + /* Package (CHILD) length */ acpigen_pop_len(); } -- cgit v1.2.3