i2c: mux: Use subsys_initcall for the i2c-arb-gpio-challenge

Commit Message

Naveen Krishna Chatradhi April 24, 2014, 3:05 p.m. UTC

From: Doug Anderson <[e-mail]>

Since many drivers rely on FETs that live behind this arbitrator, they
can't successfully probe until after the arbitrator comes up.  They
ought to handle things properly with EPROBE_DEFER and still work, but
that has some downsides:

1. Those drivers don't come up till later in the boot process.  That
   really not so nice for the LCD--we want that to init early.
2. Some drivers have bugs and don't handle EPROBE_DEFER.  Those
   drivers should be fixed but not all of them have been fixed yet.
   HDMI is one example since DRM doesn't really have good support for
   deferring probes.

With this change We end up using the same init level as the main i2c bus.

Signed-off-by: Doug Anderson <[e-mail]>
Reviewed-on: https://gerrit.chromium.org/gerrit/57007
Reviewed-by: Simon Glass <[e-mail]>
Signed-off-by: Naveen Krishna Chatradhi <[e-mail]>
---
 drivers/i2c/muxes/i2c-arb-gpio-challenge.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

Comments

Wolfram Sang May 21, 2014, 10:26 a.m. UTC | #1

On Thu, Apr 24, 2014 at 08:35:22PM +0530, Naveen Krishna Chatradhi wrote:
> From: Doug Anderson <[e-mail]>
> 
> Since many drivers rely on FETs that live behind this arbitrator, they
> can't successfully probe until after the arbitrator comes up.  They
> ought to handle things properly with EPROBE_DEFER and still work, but
> that has some downsides:
> 
> 1. Those drivers don't come up till later in the boot process.  That
>    really not so nice for the LCD--we want that to init early.
> 2. Some drivers have bugs and don't handle EPROBE_DEFER.  Those
>    drivers should be fixed but not all of them have been fixed yet.
>    HDMI is one example since DRM doesn't really have good support for
>    deferring probes.
> 
> With this change We end up using the same init level as the main i2c bus.
> 
> Signed-off-by: Doug Anderson <[e-mail]>
> Reviewed-on: https://gerrit.chromium.org/gerrit/57007
> Reviewed-by: Simon Glass <[e-mail]>
> Signed-off-by: Naveen Krishna Chatradhi <[e-mail]>

Same here. Unless we have a clear understanding that this is the only
acceptable solution in mainline, this is really an out-of-tree patch.

Patch

diff --git a/drivers/i2c/muxes/i2c-arb-gpio-challenge.c b/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
index 69afffa..6cf52bb 100644
--- a/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
+++ b/drivers/i2c/muxes/i2c-arb-gpio-challenge.c
@@ -241,7 +241,17 @@  static struct platform_driver i2c_arbitrator_driver = {
 	},
 };
 
-module_platform_driver(i2c_arbitrator_driver);
+static int __init i2c_arbitrator_init(void)
+{
+	return platform_driver_register(&i2c_arbitrator_driver);
+}
+subsys_initcall(i2c_arbitrator_init);
+
+static void __exit i2c_arbitrator_exit(void)
+{
+	platform_driver_unregister(&i2c_arbitrator_driver);
+}
+module_exit(i2c_arbitrator_exit);
 
 MODULE_DESCRIPTION("GPIO-based I2C Arbitration");
 MODULE_AUTHOR("Doug Anderson <[e-mail]>");