Re: [PATCH] rtc: Kconfig: select REGMAP for RTC_DRV_DS1307

Le 06/07/2023 à 08:14, Benjamin Gray a écrit :

On Thu, 2023-07-06 at 05:13 +0000, Christophe Leroy wrote:

quoted

Le 05/07/2023 à 02:30, Benjamin Gray a écrit :

quoted

The drivers/rtc/rtc-ds1307.c driver has a direct dependency on
struct regmap_config, which is guarded behind CONFIG_REGMAP.

Commit 70a640c0efa7 ("regmap: REGMAP_KUNIT should not select
REGMAP")
exposed this by disabling the default pick unless KUNIT_ALL_TESTS
is
set, causing the ppc64be allnoconfig build to fail.

Signed-off-by: Benjamin Gray <redacted>
---
   drivers/rtc/Kconfig | 1 +
   1 file changed, 1 insertion(+)

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index ffca9a8bb878..7455ebd189fe 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig

@@ -246,6 +246,7 @@ config RTC_DRV_AS3722
   
   config RTC_DRV_DS1307
         tristate "Dallas/Maxim DS1307/37/38/39/40/41, ST M41T00,

EPSON RX-8025, ISL12057"
+       select REGMAP

As far as I can see, REGMAP defaults to Y when REGMAP_I2C is
selected.
Can you explain more in details why you have to select it explicitely
?
If there is something wrong with the logic, then the logic should be
fixed instead of just adding a selection of REGMAP for that
particular
RTC_DRV_DS1307. Because others like RTC_DRV_ABB5ZES3 or
RTC_DRV_ABEOZ9
might have the exact same problem.

Right, yeah, I don't want to assert this patch is the correct solution,
sending it was more to offer a fix and allow discussion if it should be
resolved some other way (so thanks for replying, I appreciate it).

In terms of why I made this patch, the way I see it, if a config option
requires another config option be set, then "selects" is the natural
way of phrasing this dependency. "default" on the REGMAP side seems
weird. If it's a default, does that mean it can be overridden? But
RTC_DRV_DS1307 *requires* REGMAP; it's not just a "would be nice". The
build breaks without it.

I mean't "why doesn't it work as is", and/or "why didn't you fix what 
doesn't work".

Well, until commit 70a640c0efa7 ("regmap: REGMAP_KUNIT should not select 
REGMAP") it was not user-selectable so I couldn't be overridden.
After commit 70a640c0efa7 ("regmap: REGMAP_KUNIT should not select 
REGMAP") it is overridable so we have an additional problem.

Does RTC_DRV_DS1307 require REGMAP or does RTC_DRV_DS1307 require 
REGMAP_I2C and then REGMAP_I2C requires REGMAP ?

I think that huge default like for REGMAP should be replaced by 
individual selection of REGMAP from each of those config items. For 
exemple REGMAP_I2C should select REGMAP then I guess it would also solve 
your issue wouldn't it ?

But maybe KConfig works differently to my assumptions. Maybe the
referenced patch that causes the build failure is actually incorrect
(CC Geert). I spoke with Joel Stanley (CC) and he indicated you're not
supposed to depend on REGMAP like KUnit does?

As for other drivers having the same problem, quite possibly, yes. But
the PPC configs don't seem to build those drivers, so I'd prefer to
leave it to anyone who does build them to report the error. I wasn't
planning to audit all the drivers, I was just trying to fix the PPC
configs I build and test.

Well ok but that's probably the indication of a deeper problem which 
deserves a more generic fix.