Re: [PATCH rtw-next v1 06/13] wifi: rtw89: Disable some power saving for USB

[Bitterblue Smith <rtl8821cerfe2@gmail.com>]

On 13/05/2025 06:27, Ping-Ke Shih wrote:
> Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
>> Disable rtw89_ps_power_mode_change() and rtw89_mac_send_rpwm() for
>> USB because they are called in atomic context and accessing hardware
>> registers results in "scheduling while atomic" errors.
> 
> I feel rtw89_ps_power_mode_change() should be not in atomic context.
> Please check this. 
> 

I think you're right, only rtw89_mac_send_rpwm() is called in atomic
context. rtw89_ps_power_mode_change() is disabled for other reasons:

1) It calls rtw89_mac_power_mode_change(), which prints errors when
rtw89_mac_send_rpwm() is disabled.

2) With RTL8852CU it calls rtw89_ps_power_mode_change_with_hci()
which calls napi_schedule(). That results in dereferencing a null
pointer.

>>
>> Signed-off-by: Bitterblue Smith <rtl8821cerfe2@gmail.com>
>> ---
>>  drivers/net/wireless/realtek/rtw89/mac.c | 3 +++
>>  drivers/net/wireless/realtek/rtw89/ps.c  | 3 +++
>>  2 files changed, 6 insertions(+)
>>
>> diff --git a/drivers/net/wireless/realtek/rtw89/mac.c b/drivers/net/wireless/realtek/rtw89/mac.c
>> index a316864ad137..1a03355b340f 100644
>> --- a/drivers/net/wireless/realtek/rtw89/mac.c
>> +++ b/drivers/net/wireless/realtek/rtw89/mac.c
>> @@ -1338,6 +1338,9 @@ static void rtw89_mac_send_rpwm(struct rtw89_dev *rtwdev,
>>  {
>>         u16 request;
>>
>> +       if (rtwdev->hci.type == RTW89_HCI_TYPE_USB)
> 
> I think SDIO devices have the same problems as USB, so I prefer to return
> if "!= PCIE".
> 
>> +               return;
>> +
>>         spin_lock_bh(&rtwdev->rpwm_lock);
>>
>>         request = rtw89_read16(rtwdev, R_AX_RPWM);
>> diff --git a/drivers/net/wireless/realtek/rtw89/ps.c b/drivers/net/wireless/realtek/rtw89/ps.c
>> index ac46a7baa00d..edff9f8e1016 100644
>> --- a/drivers/net/wireless/realtek/rtw89/ps.c
>> +++ b/drivers/net/wireless/realtek/rtw89/ps.c
>> @@ -56,6 +56,9 @@ static void rtw89_ps_power_mode_change_with_hci(struct rtw89_dev *rtwdev,
>>
>>  static void rtw89_ps_power_mode_change(struct rtw89_dev *rtwdev, bool enter)
>>  {
>> +       if (rtwdev->hci.type == RTW89_HCI_TYPE_USB)
>> +               return;
>> +
>>         if (rtwdev->chip->low_power_hci_modes & BIT(rtwdev->ps_mode) &&
>>             !test_bit(RTW89_FLAG_WOWLAN, rtwdev->flags))
>>                 rtw89_ps_power_mode_change_with_hci(rtwdev, enter);
>> --
>> 2.49.0
>