Re: [PATCH v1] power: sequencing: qcom-wcn: increase WCN7850 power-up delay

[Dmitry Baryshkov]

On Mon, Nov 02, 2026 at 05:48:00PM +0800, Shuai Zhang wrote:
> When the WCN7850 is powered up from the Bluetooth side first, i.e.
> BT_EN is asserted while WLAN_EN is still low, the chip starts from a
> cold state and is not ready to accept the first HCI command 50 ms after
> BT_EN goes high. The first command (0xfc00, read QCA version) is lost,
> hci_qca does not resend it and fails after the 2 s command timeout:
> 
>   Bluetooth: hci0: Reading QCA version information failed (-110)
> 
> When WLAN is powered first, 50 ms is sufficient, so the failure only
> shows up in the BT-first ordering. Measured on the affected board by
> which enable pin rose first:
> 
>   pwup_delay_ms   BT-first boots   with -110
>   50              9                9
>   75              23               0
>   100             21               0
>   300             20               0
> 
> Raise the power-up delay of WCN7850 to 100 ms. The delay is shared by
> the Bluetooth and WLAN targets, so WLAN power-up also waits 50 ms
> longer.
> 
> Fixes: 2f1630f437df ("power: pwrseq: add a driver for the PMU module on the QCom WCN chipsets")
> Signed-off-by: Cheng Jiang <cheng.jiang@xxxxxxxxxxxxxxxx>
> Signed-off-by: Shuai Zhang <shuai.zhang@xxxxxxxxxxxxxxxx>
> ---
>  drivers/power/sequencing/pwrseq-qcom-wcn.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxxxxxxxx>

> 

-- 
With best wishes
Dmitry