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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Barry Song <Baohua.Song@csr.com>,
        Stephan Gerhold <stephan@gerhold.net>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Mark Brown <broonie@kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 055/191] mfd: mfd-core: Honour Device Trees request to disable a child-device
Date:   Thu,  2 Jan 2020 23:05:37 +0100
Message-Id: <20200102215835.819082035@linuxfoundation.org>
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From: Lee Jones <lee.jones@linaro.org>

[ Upstream commit 6b5c350648b857047b47acf74a57087ad27d6183 ]

Until now, MFD has assumed all child devices passed to it (via
mfd_cells) are to be registered. It does not take into account
requests from Device Tree and the like to disable child devices
on a per-platform basis.

Well now it does.

Link: https://www.spinics.net/lists/arm-kernel/msg366309.html
Link: https://lkml.org/lkml/2019/8/22/1350

Reported-by: Barry Song <Baohua.Song@csr.com>
Reported-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Reviewed-by: Mark Brown <broonie@kernel.org>
Tested-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/mfd/mfd-core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index 23276a80e3b4..b0afefdc9eac 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -174,6 +174,11 @@ static int mfd_add_device(struct device *parent, int id,
 	if (parent->of_node && cell->of_compatible) {
 		for_each_child_of_node(parent->of_node, np) {
 			if (of_device_is_compatible(np, cell->of_compatible)) {
+				if (!of_device_is_available(np)) {
+					/* Ignore disabled devices error free */
+					ret = 0;
+					goto fail_alias;
+				}
 				pdev->dev.of_node = np;
 				pdev->dev.fwnode = &np->fwnode;
 				break;
-- 
2.20.1