Re: [PATCH for v4.9-stable] reset: make optional functions really optional

[Dinh Nguyen <dinguyen@kernel.org>]

On 12/3/18 11:45 AM, Greg KH wrote:
> On Mon, Dec 03, 2018 at 11:30:29AM -0600, Dinh Nguyen wrote:
>> From: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
>>
>> commit bb475230b8e59a547ab66ac3b02572df21a580e9 upstream.
>>
>> The *_get_optional_* functions weren't really optional so this patch
>> makes them really optional.
>>
>> These *_get_optional_* functions will now return NULL instead of an error
>> if no matching reset phandle is found in the DT, and all the
>> reset_control_* functions now accept NULL rstc pointers.
>>
>> Signed-off-by: Ramiro Oliveira <Ramiro.Oliveira@synopsys.com>
>> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
>> ---
>> Please apply to v4.9.y stable tree.
>> ---
>>  drivers/reset/core.c  | 48 +++++++++++++++++++++++++++++++++----------
>>  include/linux/reset.h | 45 +++++++++++++++++++++++-----------------
>>  2 files changed, 63 insertions(+), 30 deletions(-)
> 
> What problem is this solving?  Why is this suddenly needed now?
> 

The v4.9-stable branch has this patch for stmmac ethernet driver:

"6f37f7b62baa net: stmmac: socfpga: add additional ocp reset line for
Stratix10"

This patch calls devm_reset_control_get_optional(). This call ultimately
fails without optional reset patch, causing the ethernet driver to fail
to load.

Dinh