The SDIO HCI implementation needs to know when the MAC is powered on.
This is needed because 32-bit register access has to be split into 4x
8-bit register access when the MAC is not fully powered on or while
powering off. When the MAC is powered on 32-bit register access can be
used to reduce the number of transfers but splitting into 4x 8-bit
register access still works in that case.
During the power on sequence is how RTW_FLAG_POWERON is only set when
the power on sequence has completed successfully. During power off
however RTW_FLAG_POWERON is set. This means that the upcoming SDIO HCI
implementation does not know that it has to use 4x 8-bit register
accessors. Clear the RTW_FLAG_POWERON flag early when powering off the
MAC so the whole power off sequence is processed with RTW_FLAG_POWERON
unset. This will make it possible to use the RTW_FLAG_POWERON flag in
the upcoming SDIO HCI implementation.
Note that a failure in rtw_pwr_seq_parser() while applying
chip->pwr_off_seq can theoretically result in the RTW_FLAG_POWERON
flag being cleared while the chip is still powered on. However,
depending on when the failure occurs in the power off sequence the
chip may be on or off. Even the original approach of clearing
RTW_FLAG_POWERON only when the power off sequence has been applied
successfully could end up in some corner case where the chip is
powered off but RTW_FLAG_POWERON was not cleared.
Reviewed-by: Ping-Ke Shih <[email protected]>
Signed-off-by: Martin Blumenstingl <[email protected]>
---
Changes since v4:
- none
Changes since v3:
- added Ping-Ke's reviewed-by (thank you!)
Changes since v2:
- improve patch description about corner cases when clearing
RTW_FLAG_POWERON
Changes since v1:
- This replaces a previous patch called "rtw88: hci: Add an optional
power_switch() callback to rtw_hci_ops" which added a new callback
to the HCI ops.
drivers/net/wireless/realtek/rtw88/mac.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/net/wireless/realtek/rtw88/mac.c b/drivers/net/wireless/realtek/rtw88/mac.c
index f3a566cf979b..cfdfc8a2c836 100644
--- a/drivers/net/wireless/realtek/rtw88/mac.c
+++ b/drivers/net/wireless/realtek/rtw88/mac.c
@@ -273,6 +273,9 @@ static int rtw_mac_power_switch(struct rtw_dev *rtwdev, bool pwr_on)
if (pwr_on == cur_pwr)
return -EALREADY;
+ if (!pwr_on)
+ clear_bit(RTW_FLAG_POWERON, rtwdev->flags);
+
pwr_seq = pwr_on ? chip->pwr_on_seq : chip->pwr_off_seq;
ret = rtw_pwr_seq_parser(rtwdev, pwr_seq);
if (ret)
@@ -280,8 +283,6 @@ static int rtw_mac_power_switch(struct rtw_dev *rtwdev, bool pwr_on)
if (pwr_on)
set_bit(RTW_FLAG_POWERON, rtwdev->flags);
- else
- clear_bit(RTW_FLAG_POWERON, rtwdev->flags);
return 0;
}
--
2.40.0
Martin Blumenstingl <[email protected]> wrote:
> The SDIO HCI implementation needs to know when the MAC is powered on.
> This is needed because 32-bit register access has to be split into 4x
> 8-bit register access when the MAC is not fully powered on or while
> powering off. When the MAC is powered on 32-bit register access can be
> used to reduce the number of transfers but splitting into 4x 8-bit
> register access still works in that case.
>
> During the power on sequence is how RTW_FLAG_POWERON is only set when
> the power on sequence has completed successfully. During power off
> however RTW_FLAG_POWERON is set. This means that the upcoming SDIO HCI
> implementation does not know that it has to use 4x 8-bit register
> accessors. Clear the RTW_FLAG_POWERON flag early when powering off the
> MAC so the whole power off sequence is processed with RTW_FLAG_POWERON
> unset. This will make it possible to use the RTW_FLAG_POWERON flag in
> the upcoming SDIO HCI implementation.
>
> Note that a failure in rtw_pwr_seq_parser() while applying
> chip->pwr_off_seq can theoretically result in the RTW_FLAG_POWERON
> flag being cleared while the chip is still powered on. However,
> depending on when the failure occurs in the power off sequence the
> chip may be on or off. Even the original approach of clearing
> RTW_FLAG_POWERON only when the power off sequence has been applied
> successfully could end up in some corner case where the chip is
> powered off but RTW_FLAG_POWERON was not cleared.
>
> Reviewed-by: Ping-Ke Shih <[email protected]>
> Signed-off-by: Martin Blumenstingl <[email protected]>
9 patches applied to wireless-next.git, thanks.
6a92566088b1 wifi: rtw88: Clear RTW_FLAG_POWERON early in rtw_mac_power_switch()
65371a3f14e7 wifi: rtw88: sdio: Add HCI implementation for SDIO based chipsets
b722e5b130bc wifi: rtw88: mac: Support SDIO specific bits in the power on sequence
a5d25f9ff918 wifi: rtw88: main: Add the {cpwm,rpwm}_addr for SDIO based chipsets
02461d9368c5 wifi: rtw88: main: Reserve 8 bytes of extra TX headroom for SDIO cards
7d6d2dd326a8 mmc: sdio: add Realtek SDIO vendor ID and various wifi device IDs
095e62dd7427 wifi: rtw88: Add support for the SDIO based RTL8822BS chipset
6fdacb78f799 wifi: rtw88: Add support for the SDIO based RTL8822CS chipset
b2a777d68434 wifi: rtw88: Add support for the SDIO based RTL8821CS chipset
--
https://patchwork.kernel.org/project/linux-wireless/patch/[email protected]/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches