[PATCH] Revert "ath: add support for special 0x0 regulatory domain"

["Alvin Šipraga" <alsi@bang-olufsen.dk>]

This reverts commit 2dc016599cfa9672a147528ca26d70c3654a5423.

Per Atheros documentation to manufacturers, the EEPROM regulatory domain
code 0x0 must always map to "US". In particular, it should not map to a
custom world regulatory domain. For references, see [1] and [2] below.
Furthermore, __ath_regd_init() has a specific condition to set the
country code to "US" in this case, which emits the following log
message:

[    7.814307] ath: EEPROM indicates default country code should be used

The patch being reverted mistakenly maps 0x0 to the custom world
regulatory domain 0x64 - the most restrictive of the world regulatory
domains. The premise of the patch is that in the case of EEPROM
regulatory domain code 0x0, ath_is_world_regd() should return true. But,
as stated above, 0x0 should not map to a world regulatory domain, and so
the function should return false. The original behaviour, whereby
NL80211_REGDOM_SET_BY_COUNTRY_IE is ignored, was correct according to
the manufacturer's intent and should not have been changed.

[1] https://wireless.wiki.kernel.org/en/users/drivers/ath#the_0x0_regulatory_domain
[2] http://article.gmane.org/gmane.linux.kernel.wireless.general/38410

Fixes: 2dc016599cfa ("ath: add support for special 0x0 regulatory domain")
Cc: Wen Gong <wgong@codeaurora.org>
Cc: Luis R. Rodriguez <mcgrof@kernel.org>
Cc: linux-wireless@vger.kernel.org
Tested-on: QCA9880 hw2.0 PCI 10.2.4-1.0-00047
Signed-off-by: Alvin Šipraga <alsi@bang-olufsen.dk>
---
 drivers/net/wireless/ath/regd.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/net/wireless/ath/regd.c b/drivers/net/wireless/ath/regd.c
index bee9110b91f3..20f4f8ea9f89 100644
--- a/drivers/net/wireless/ath/regd.c
+++ b/drivers/net/wireless/ath/regd.c
@@ -666,14 +666,14 @@ ath_regd_init_wiphy(struct ath_regulatory *reg,
 
 /*
  * Some users have reported their EEPROM programmed with
- * 0x8000 or 0x0 set, this is not a supported regulatory
- * domain but since we have more than one user with it we
- * need a solution for them. We default to 0x64, which is
- * the default Atheros world regulatory domain.
+ * 0x8000 set, this is not a supported regulatory domain
+ * but since we have more than one user with it we need
+ * a solution for them. We default to 0x64, which is the
+ * default Atheros world regulatory domain.
  */
 static void ath_regd_sanitize(struct ath_regulatory *reg)
 {
-	if (reg->current_rd != COUNTRY_ERD_FLAG && reg->current_rd != 0)
+	if (reg->current_rd != COUNTRY_ERD_FLAG)
 		return;
 	printk(KERN_DEBUG "ath: EEPROM regdomain sanitized\n");
 	reg->current_rd = 0x64;
-- 
2.27.0