On 4/14/24 7:45 PM, Ping-Ke Shih wrote:
Larry Finger <larry.finger@xxxxxxxxx> wrote:
I originally wondered if there was a power problem when both were simultaneously
started, but I see that is not the case. To reiterate, the BT must start first
and complete UART initialization before the wifi starts initializing. It seems
to me that a suitable msleep() at the start of the SDIO probe routine seems to
be a viable workaround even though it is not aesthetically pleasing. A sleep of
150 ms is too short, but 500 seems to work reliably.
Suggest to apply this workaround but only if UART-BT + SDIO-WiFi, because SDIO
experts didn't remember they have met this problem. They need real hardware to
measure signals to know what it is wrong, but unfortunately they don't have
bandwidth to process this because of limitation of human resources. Sorry
for that.
The OP at GitHub reported today that there was a DTB error for that chip [1]. I
am going to drop the patch for the stable kernel, but I will still apply it to
my rtw88 repo at GitHub.com. That way, users with older kernels will get the
benefit of the msleep() even though their DTB may not be fixed.
Thanks to you and the SDIO team for your efforts toward a problem that turned
out to be in the kernel. Sorry for some noise.
Larry
[1]
https://github.com/ROCKNIX/distribution/pull/63/files#diff-e2de6222b1794f89311bdc1597c1597c76f34503c575ea3f7e7ec9c5376218d6
