[PATCH] iwlwifi: mvm: Avoid use of GEO_TX_POWER_LIMIT when not supported

[PATCH] iwlwifi: mvm: Avoid use of GEO_TX_POWER_LIMIT when not supported

[Jonathan McDowell]

Commit 39c1a9728f93 refactored the SAR table support and inadvertently
added a call to GEO_TX_POWER_LIMIT without checking that the firmware
supported it. This caused a regression for device + firmware
combinations lacking the support. Add a check in iwl_mvm_sar_init to
prevent this.

Fixes: 39c1a9728f93 (iwlwifi: refactor the SAR tables from mvm to acpi)
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206395
Cc: stable@vger.kernel.org # 5.5
Signed-Off-By: Jonathan McDowell <noodles@earth.li>

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/fw.c b/drivers/net/wireless/intel/iwlwifi/mvm/fw.c
index 54c094e88474..4a8a4cb2c553 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/fw.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/fw.c
@@ -1007,6 +1007,13 @@ static int iwl_mvm_sar_init(struct iwl_mvm *mvm)
 	if (ret == -ENOENT)
 		return 1;
 
+	/*
+	 * If our firmware doesn't support GEO_TX_POWER_LIMIT then skip trying
+	 * to use it.
+	 */
+	if (!iwl_sar_geo_support(&mvm->fwrt))
+		return 1;
+
 	return ret;
 }
 

-- 
... Don't do it!

Re: [PATCH] iwlwifi: mvm: Avoid use of GEO_TX_POWER_LIMIT when not supported

[Luca Coelho]

On Sat, 2020-03-14 at 10:57 +0000, Jonathan McDowell wrote:
> Commit 39c1a9728f93 refactored the SAR table support and inadvertently
> added a call to GEO_TX_POWER_LIMIT without checking that the firmware
> supported it. This caused a regression for device + firmware
> combinations lacking the support. Add a check in iwl_mvm_sar_init to
> prevent this.
> 
> Fixes: 39c1a9728f93 (iwlwifi: refactor the SAR tables from mvm to acpi)
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=206395
> Cc: stable@vger.kernel.org # 5.5
> Signed-Off-By: Jonathan McDowell <noodles@earth.li>
> 
> diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/fw.c b/drivers/net/wireless/intel/iwlwifi/mvm/fw.c
> index 54c094e88474..4a8a4cb2c553 100644
> --- a/drivers/net/wireless/intel/iwlwifi/mvm/fw.c
> +++ b/drivers/net/wireless/intel/iwlwifi/mvm/fw.c
> @@ -1007,6 +1007,13 @@ static int iwl_mvm_sar_init(struct iwl_mvm *mvm)
>  	if (ret == -ENOENT)
>  		return 1;
>  
> +	/*
> +	 * If our firmware doesn't support GEO_TX_POWER_LIMIT then skip trying
> +	 * to use it.
> +	 */
> +	if (!iwl_sar_geo_support(&mvm->fwrt))
> +		return 1;
> +
>  	return ret;
>  }

Thanks, Jonathan! We already have an internal patch that fixes this 
(also fixes another symptom of the same bug).  I'll send it out now.

--
Cheers,
Luca.