linux-kernel - Re: [patch 2.6.24-git] rtc: avoid legacy drivers with generic framework

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Date:	Sat, 8 Mar 2008 11:19:29 -0800
From:	David Brownell <david-b@...bell.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	rtc-linux@...glegroups.com, lkml <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...e.hu>, Pavel Machek <pavel@....cz>
Subject: Re: [patch 2.6.24-git] rtc: avoid legacy drivers with generic framework

On Sunday 10 February 2008, David Brownell wrote:
> Kconfig tweaks to help reduce RTC configuration bugs, by avoiding
> legacy RTC drivers when the generic RTC framework is enabled:
> 
>  - If rtc-cmos is selected, disable the legacy rtc driver;
> 
>  - When using generic RTC on x86, enable rtc-cmos by default;
> 
>  - In the old "chardev RTC" section of Kconfig, add a comment
>    warning people off these (seven) legacy RTC drivers when
>    the generic framework is in use.
> 
> People can still use the legacy drivers if they want (or need) to.
> 
> Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
> 	...

Here's an update to that patch, which is in MMOTM with the name

	rtc-avoid-legacy-drivers-with-generic-framework.patch

=======
This is a harsher fix for the problems of trying to make legacy
RTCs coexist with the generic RTC framework:  Just Don't Do It.

The legacy drivers are not geared towards coexistence; they
never had a reason to try.  So rather than accumulating more
and more special cases, and gently nudging users away from the
old code, make it be an either/or choice.

Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
 drivers/char/Kconfig |   12 ++++++++----
 drivers/rtc/Kconfig  |    4 ----
 2 files changed, 8 insertions(+), 8 deletions(-)

--- g26.orig/drivers/char/Kconfig	2008-03-07 13:28:53.000000000 -0800
+++ g26/drivers/char/Kconfig	2008-03-07 13:35:07.000000000 -0800
@@ -704,14 +704,16 @@ config NVRAM
 	  To compile this driver as a module, choose M here: the
 	  module will be called nvram.
 
-comment "Avoid any legacy RTC drivers you may see here"
-	depends on RTC_LIB
+#
+# These legacy RTC drivers just cause too many conflicts with the generic
+# RTC framework ... let's not even try to coexist any more.
+#
+if RTC_LIB=n
 
 config RTC
 	tristate "Enhanced Real Time Clock Support"
 	depends on !PPC && !PARISC && !IA64 && !M68K && !SPARC && !FRV \
-			&& !ARM && !SUPERH && !S390 \
-			&& RTC_DRV_CMOS=n
+			&& !ARM && !SUPERH && !S390
 	---help---
 	  If you say Y here and create a character special file /dev/rtc with
 	  major number 10 and minor number 135 using mknod ("man mknod"), you
@@ -817,6 +819,8 @@ config DS1302
 	  will get access to the real time clock (or hardware clock) built
 	  into your computer.
 
+endif # RTC_LIB
+
 config COBALT_LCD
 	bool "Support for Cobalt LCD"
 	depends on MIPS_COBALT
--- g26.orig/drivers/rtc/Kconfig	2008-03-07 13:28:53.000000000 -0800
+++ g26/drivers/rtc/Kconfig	2008-03-07 13:31:28.000000000 -0800
@@ -20,10 +20,6 @@ menuconfig RTC_CLASS
 
 if RTC_CLASS
 
-if GEN_RTC || RTC
-comment "Conflicting RTC option has been selected, check GEN_RTC and RTC"
-endif
-
 config RTC_HCTOSYS
 	bool "Set system time from RTC on startup and resume"
 	depends on RTC_CLASS = y
--
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