Re: [PATCH wireless] wifi: mt76: mt7915: add module param to select 5 GHz or 6 GHz on MT7916

[Ben Greear <greearb@candelatech.com>]

On 10/10/24 01:38, Felix Fietkau wrote:
> From: Shayne Chen <shayne.chen@mediatek.com>
> 
> Due to a limitation in available memory, the MT7916 firmware can only
> handle either 5 GHz or 6 GHz at a time. It does not support runtime
> switching without a full restart.

Can this also be implemented so that we can change the module parameter,
force the radio to do a hard reset, and change bands that way, without
having to do a reboot?

Thanks,
Ben

> 
> On older firmware, this accidentally worked to some degree due to missing
> checks, but couldn't be supported properly, because it left the 6 GHz
> channels uncalibrated.
> Newer firmware refuses to start on either band if the passed EEPROM
> data indicates support for both.
> 
> Deal with this limitation by using a module parameter to specify the
> preferred band in case both are supported.
> 
> Fixes: b4d093e321bd ("mt76: mt7915: add 6 GHz support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>   .../wireless/mediatek/mt76/mt7915/eeprom.c    | 21 +++++++++++++++++--
>   .../net/wireless/mediatek/mt76/mt7915/init.c  |  4 ++--
>   2 files changed, 21 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c b/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c
> index bfdbc15abaa9..928e0b07a9bf 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/eeprom.c
> @@ -2,9 +2,14 @@
>   /* Copyright (C) 2020 MediaTek Inc. */
>   
>   #include <linux/firmware.h>
> +#include <linux/moduleparam.h>
>   #include "mt7915.h"
>   #include "eeprom.h"
>   
> +static bool enable_6ghz;
> +module_param(enable_6ghz, bool, 0644);
> +MODULE_PARM_DESC(enable_6ghz, "Enable 6 GHz instead of 5 GHz on hardware that supports both");
> +
>   static int mt7915_eeprom_load_precal(struct mt7915_dev *dev)
>   {
>   	struct mt76_dev *mdev = &dev->mt76;
> @@ -170,8 +175,20 @@ static void mt7915_eeprom_parse_band_config(struct mt7915_phy *phy)
>   			phy->mt76->cap.has_6ghz = true;
>   			return;
>   		case MT_EE_V2_BAND_SEL_5GHZ_6GHZ:
> -			phy->mt76->cap.has_5ghz = true;
> -			phy->mt76->cap.has_6ghz = true;
> +			if (enable_6ghz) {
> +				phy->mt76->cap.has_6ghz = true;
> +				u8p_replace_bits(&eeprom[MT_EE_WIFI_CONF + band],
> +						 MT_EE_V2_BAND_SEL_6GHZ,
> +						 MT_EE_WIFI_CONF0_BAND_SEL);
> +			} else {
> +				phy->mt76->cap.has_5ghz = true;
> +				u8p_replace_bits(&eeprom[MT_EE_WIFI_CONF + band],
> +						 MT_EE_V2_BAND_SEL_5GHZ,
> +						 MT_EE_WIFI_CONF0_BAND_SEL);
> +			}
> +			/* force to buffer mode */
> +			dev->flash_mode = true;
> +
>   			return;
>   		default:
>   			phy->mt76->cap.has_2ghz = true;
> diff --git a/drivers/net/wireless/mediatek/mt76/mt7915/init.c b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> index 6bef96e3d2a3..f82216d1bda0 100644
> --- a/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> +++ b/drivers/net/wireless/mediatek/mt76/mt7915/init.c
> @@ -1239,14 +1239,14 @@ int mt7915_register_device(struct mt7915_dev *dev)
>   	if (ret)
>   		goto unreg_dev;
>   
> -	ieee80211_queue_work(mt76_hw(dev), &dev->init_work);
> -
>   	if (phy2) {
>   		ret = mt7915_register_ext_phy(dev, phy2);
>   		if (ret)
>   			goto unreg_thermal;
>   	}
>   
> +	ieee80211_queue_work(mt76_hw(dev), &dev->init_work);
> +
>   	dev->recovery.hw_init_done = true;
>   
>   	ret = mt7915_init_debugfs(&dev->phy);

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com