Subject: Re: [PATCH net-next] docs: 3c509: remove note about card detection failing with overclock

From: Ethan Nelson-Moore <[email-masked]>
Date: Mon, 27 Apr 2026 22:20:03 -0700

Hi, Maciej,

Sorry for the extreme delay in responding - I somehow missed this message.

On 26 Jan 2026 Maciej W. Rozycki wrote:
> -- so it's not about using a time-based vs some other kind of delay.  The
> comment to be removed was only added along with the whole document on the
> 3c509 driver with Linux 2.5.13, much later (2002 vs 1998), and therefore
> still stands.

I traced back the usage of udelay in this driver and found that id_read_eeprom
did in fact use a busy waiting loop before kernel 2.0.14:

https://github.com/schwabe/davej-history/commit/8cf64f0c94dcbf029dc3b12cb8e2afba590f8f72#diff-9acb56ec07fd10ccce51b1dc719976d60ee5a947dec31174e2a96f871fde72f9L331

This is probably what the comment was referring to, and therefore it is in fact
incorrect. The documentation appears to have been imported from the Scyld
out-of-tree driver (the basis of the mainline driver), which still mentioned the
issue in 2003:
https://web.archive.org/web/20030605134029/http://www.scyld.com/network/3c509.html

I was not able to find a copy of an old Scyld driver easily to see if it was
affected by the issue.

Hope that clarifies the situation.

Ethan