RE: [PATCH rtw-next 1/2] wifi: rtw89: Increase polling delay in rtw89_fw_read_c2h_reg() for USB

[Ping-Ke Shih <pkshih@realtek.com>]

Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> On 14/07/2025 05:49, Ping-Ke Shih wrote:
> > Bitterblue Smith <rtl8821cerfe2@gmail.com> wrote:
> >> This read_poll_timeout_atomic() with a delay of 1 µs and a timeout of
> >> 1000000 µs can take ~250 seconds in the worst case because sending a
> >> USB control message takes ~250 µs.
> >
> > I was not aware of the change of [1]. The behavior of atomic version becomes
> > different from non-atomic version.
> >
> > For this patch, I feel we can keep delay_us to 1 and treat timeout_us as
> > 'count', which USB devices do smaller retries. The smaller delay_us can
> > reduce total polling time, especially for PCIE devices (see my comments below)
> >
> > Though I don't measure total polling time of patch 2/2, I feel we can apply
> > similar idea.
> >
> 
> Yes, a smaller timeout also works. I tested 4000 for this patch and 3200
> for patch 2. 

Forgot to say, for PCIE devices please keep the timeout as was.

> (4000 * 250 = 1000000 and 3200 * 125 = 400000. I don't know
> why rtw89_read8() in the second patch takes only 125 µs.)