ath9k: Check for errors when reading SREV register

BugLink: https://bugs.launchpad.net/bugs/1839036
[ Upstream commit 2f90c7e5d09437a4d8d5546feaae9f1cf48cfbe1 ]

Right now, if an error is encountered during the SREV register
read (i.e. an EIO in ath9k_regread()), that error code gets
passed all the way to __ath9k_hw_init(), where it is visible
during the "Chip rev not supported" message.

    ath9k_htc 1-1.4:1.0: ath9k_htc: HTC initialized with 33 credits
    ath: phy2: Mac Chip Rev 0x0f.3 is not supported by this driver
    ath: phy2: Unable to initialize hardware; initialization status: -95
    ath: phy2: Unable to initialize hardware; initialization status: -95
    ath9k_htc: Failed to initialize the device

Check for -EIO explicitly in ath9k_hw_read_revisions() and return
a boolean based on the success of the operation. Check for that in
__ath9k_hw_init() and abort with a more debugging-friendly message
if reading the revisions wasn't successful.

    ath9k_htc 1-1.4:1.0: ath9k_htc: HTC initialized with 33 credits
    ath: phy2: Failed to read SREV register
    ath: phy2: Could not read hardware revision
    ath: phy2: Unable to initialize hardware; initialization status: -95
    ath: phy2: Unable to initialize hardware; initialization status: -95
    ath9k_htc: Failed to initialize the device

This helps when debugging by directly showing the first point of
failure and it could prevent possible errors if a 0x0f.3 revision
is ever supported.

Signed-off-by: Tim Schumacher <timschumi@gmx.de>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/wireless/ath/ath9k/hw.c b/drivers/net/wireless/ath/ath9k/hw.c
index 5439b5854f3727c8f44e3320c5e02038e9a79883..e936c8f28ccd490ba6aef4800a00e6ff3f03a05f 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/hw.c
+++ b/drivers/net/wireless/ath/ath9k/hw.c
@@ -250,8 +250,9 @@ void ath9k_hw_get_channel_centers(struct ath_hw *ah,
 /* Chip Revisions */
 /******************/
 
-static void ath9k_hw_read_revisions(struct ath_hw *ah)
+static bool ath9k_hw_read_revisions(struct ath_hw *ah)
 {
+       u32 srev;
        u32 val;
 
        if (ah->get_mac_revision)
@@ -267,25 +268,33 @@ static void ath9k_hw_read_revisions(struct ath_hw *ah)
                        val = REG_READ(ah, AR_SREV);
                        ah->hw_version.macRev = MS(val, AR_SREV_REVISION2);
                }
-               return;
+               return true;
        case AR9300_DEVID_AR9340:
                ah->hw_version.macVersion = AR_SREV_VERSION_9340;
-               return;
+               return true;
        case AR9300_DEVID_QCA955X:
                ah->hw_version.macVersion = AR_SREV_VERSION_9550;
-               return;
+               return true;
        case AR9300_DEVID_AR953X:
                ah->hw_version.macVersion = AR_SREV_VERSION_9531;
-               return;
+               return true;
        case AR9300_DEVID_QCA956X:
                ah->hw_version.macVersion = AR_SREV_VERSION_9561;
-               return;
+               return true;
        }
 
-       val = REG_READ(ah, AR_SREV) & AR_SREV_ID;
+       srev = REG_READ(ah, AR_SREV);
+
+       if (srev == -EIO) {
+               ath_err(ath9k_hw_common(ah),
+                       "Failed to read SREV register");
+               return false;
+       }
+
+       val = srev & AR_SREV_ID;
 
        if (val == 0xFF) {
-               val = REG_READ(ah, AR_SREV);
+               val = srev;
                ah->hw_version.macVersion =
                        (val & AR_SREV_VERSION2) >> AR_SREV_TYPE2_S;
                ah->hw_version.macRev = MS(val, AR_SREV_REVISION2);
@@ -304,6 +313,8 @@ static void ath9k_hw_read_revisions(struct ath_hw *ah)
                if (ah->hw_version.macVersion == AR_SREV_VERSION_5416_PCIE)
                        ah->is_pciexpress = true;
        }
+
+       return true;
 }
 
 /************************************/
@@ -557,7 +568,10 @@ static int __ath9k_hw_init(struct ath_hw *ah)
        struct ath_common *common = ath9k_hw_common(ah);
        int r = 0;
 
-       ath9k_hw_read_revisions(ah);
+       if (!ath9k_hw_read_revisions(ah)) {
+               ath_err(common, "Could not read hardware revisions");
+               return -EOPNOTSUPP;
+       }
 
        switch (ah->hw_version.macVersion) {
        case AR_SREV_VERSION_5416_PCI: