As discussed in the links below, the SDIO part of RTW8821CS fails to start correctly if such startup happens while the UART portion of the chip is initializing. The logged results with such failure is [ 10.230516] rtw_8821cs mmc3:0001:1: Start of rtw_sdio_probe [ 10.306569] Bluetooth: HCI UART driver ver 2.3 [ 10.306717] Bluetooth: HCI UART protocol Three-wire (H5) registered [ 10.307167] of_dma_request_slave_channel: dma-names property of node '/serial@fe650000' missing or empty [ 10.307199] dw-apb-uart fe650000.serial: failed to request DMA [ 10.543474] rtw_8821cs mmc3:0001:1: Firmware version 24.8.0, H2C version 12 [ 10.730744] rtw_8821cs mmc3:0001:1: sdio read32 failed (0x11080): -110 [ 10.730923] rtw_8821cs mmc3:0001:1: sdio write32 failed (0x11080): -110 Due to the above errors, wifi fails to work. For those instances when wifi works, the following is logged: [ 10.452861] Bluetooth: HCI UART protocol Three-wire (H5) registered [ 10.453580] of_dma_request_slave_channel: dma-names property of node '/serial@fe650000' missing or empty [ 10.453621] dw-apb-uart fe650000.serial: failed to request DMA [ 10.455741] rtw_8821cs mmc3:0001:1: Start of rtw_sdio_probe [ 10.639186] rtw_8821cs mmc3:0001:1: Firmware version 24.8.0, H2C version 12 In this case, SDIO wifi works correctly. The correct case is ensured by adding an mdelay(500) statement before the call to rtw_core_init(). No adverse effects are observed. Link: https://1EHFQ.trk.elasticemail.com/tracking/click?d=1UfsVowwwMAM6kBoyumkHP3o7pYa4kGXhuklYI-QPLuVUi2ohkUG8HssjZcN67C_BtzEo2aHgjSDxQlrbonuUL2yHlv5pJROamOlEnjxhjX6ma_XKx_YvnBTmqM6sQUhF4_8B7TjnnuY5TJAxA5Oeoc023DnWr-zvOPBcKJFuOGC0 Link: https://1EHFQ.trk.elasticemail.com/tracking/click?d=XUEf4t8W9xt0czASPOeeDt8BnPqLK_YeGMMwadyXNu17p5TeSDk6RmEZ25rBt0-C5d-GR5IlKqu5URoKaespUAOAffgoysVTLbvgzQoAO57Ix1ChR-fYsf2VGRa1vIR9iWmNK1bUBvdHTZb0StprYd71qCHjhdARdl8m0L3guFDpSzFekW-tapcjw0BgugcDKvlwg4DghhYs4OnIL56wuPTzyAEpDh1rQd9BBRYp0kzW0 Fixes: 65371a3f14e7 ("wifi: rtw88: sdio: Add HCI implementation for SDIO based chipsets") Signed-off-by: Larry Finger <Larry.Finger@xxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx # v6.4+ --- drivers/net/wireless/realtek/rtw88/sdio.c | 28 +++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/drivers/net/wireless/realtek/rtw88/sdio.c b/drivers/net/wireless/realtek/rtw88/sdio.c index 0cae5746f540..eec0ad85be72 100644 --- a/drivers/net/wireless/realtek/rtw88/sdio.c +++ b/drivers/net/wireless/realtek/rtw88/sdio.c @@ -1325,6 +1325,34 @@ int rtw_sdio_probe(struct sdio_func *sdio_func, rtwdev->hci.ops = &rtw_sdio_ops; rtwdev->hci.type = RTW_HCI_TYPE_SDIO; + /* Insert a delay of 500 ms. Without the delay, the wifi part + * and the UART that controls Bluetooth interfere with one + * another resulting in the following being logged: + * + * Start of SDIO probe function. + * Bluetooth: HCI UART driver ver 2.3 + * Bluetooth: HCI UART protocol Three-wire (H5) registered + * of_dma_request_slave_channel: dma-names property of node '/serial@fe650000' + * missing or empty + * dw-apb-uart fe650000.serial: failed to request DMA +` * rtw_8821cs mmc3:0001:1: Firmware version 24.8.0, H2C version 12 + * rtw_8821cs mmc3:0001:1: sdio read32 failed (0x11080): -110 + * + * If the UART is finished initializing before the SDIO probe + * function startw, the following is logged: + * + * Bluetooth: HCI UART protocol Three-wire (H5) registered + * of_dma_request_slave_channel: dma-names property of node '/serial@fe650000' + * missing or empty + * dw-apb-uart fe650000.serial: failed to request DMA + * Start of SDIO probe function. + * rtw_8821cs mmc3:0001:1: Firmware version 24.8.0, H2C version 12 + * Bluetooth: hci0: RTL: examining hci_ver=08 hci_rev=000c lmp_ver=08 lmp_subver=8821 + * SDIO wifi works correctly. + * + * No adverse effects are observed from the delay. + */ + mdelay(500); ret = rtw_core_init(rtwdev); if (ret) goto err_release_hw; -- 2.44.0 https://1EHFQ.trk.elasticemail.com/tracking/unsubscribe?d=XjvOA0R6jwFES_UmJ2Qt6yxg5cowtZ3gnLhcahwZlzF1HexUZWhPQ26VvnZeA147YLSNXF0kfAcfHhFPszjKkdNpUh1XcSY-T-r5EAwp11F10
