linux-kernel - Re: (subset) [PATCH 1/3] rtc-mc146818-lib: reduce RTC

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Date:   Fri, 24 Jun 2022 18:45:11 +0200
From:   alexandre.belloni@...tlin.com
To:     linux-kernel@...r.kernel.org, mat.jonczyk@...pl,
        linux-rtc@...r.kernel.org
Cc:     Alexandre Belloni <alexandre.belloni@...tlin.com>, bp@...en8.de,
        hpa@...or.com, x86@...nel.org, dave.hansen@...ux.intel.com,
        a.zummo@...ertech.it, tglx@...utronix.de, mingo@...hat.com
Subject: Re: (subset) [PATCH 1/3] rtc-mc146818-lib: reduce RTC_UIP polling period

From: Alexandre Belloni <alexandre.belloni@...tlin.com>

On Fri, 25 Feb 2022 22:50:09 +0100, Mateusz Jończyk wrote:
> Waiting 1ms every time is not necessary, for example on some AMD boxes
> the RTC_UIP bit is documented as being high for around 270 microseconds
> in some cases [1], which agreed with experiments on an SB710
> southbridge. So 100us seems optimal.
> 
> This in preparation for mach_get_cmos_time() refactoring.
> The functions mc146818_get_time() and mach_get_cmos_time() in
> arch/x86/kernel/rtc.c perform the same function and the code is
> duplicated. mach_get_cmos_time() is busy waiting for the RTC_UIP
> bit to clear, so make mc146818_get_time() more similar to it by reducing
> the polling period.
> 
> [...]

Applied, thanks!

[1/3] rtc-mc146818-lib: reduce RTC_UIP polling period
      commit: 4b94a798e1ca59f4614f5ff6b94fe0c287412b9b

Best regards,
-- 
Alexandre Belloni <alexandre.belloni@...tlin.com>