Re: [PATCH 1/2] alpha: add a delay between RTC port write and read
From: Arnd Bergmann <arnd@arndb.de>
Date: 2020-05-06 14:20:59
Also in:
linux-rtc, linux-serial
On Wed, May 6, 2020 at 1:21 PM Mikulas Patocka [off-list ref] wrote:
/*
* The yet supported machines all access the RTC index register via
* an ISA port access but the way to access the date register differs ...
+ *
+ * The ISA bus on Alpha Avanti doesn't like back-to-back accesses,
+ * we need to add a small delay.
*/
#define CMOS_READ(addr) ({ \
outb_p((addr),RTC_PORT(0)); \
+udelay(2); \
inb_p(RTC_PORT(1)); \
The inb_p() / outb_p() functions are meant to already have a delay in them,
maybe we should just add it there for alpha?
Arnd