linux-kernel - [PATCH V2] staging: fieldbus: anybus-s: force endiannes annotation

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Message-Id: <1556517940-13725-1-git-send-email-hofrat@osadl.org>
Date:   Mon, 29 Apr 2019 08:05:39 +0200
From:   Nicholas Mc Guire <hofrat@...dl.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Sven Van Asbroeck <thesven73@...il.com>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org,
        Nicholas Mc Guire <hofrat@...dl.org>
Subject: [PATCH V2] staging: fieldbus: anybus-s: force endiannes annotation

While the endiannes is being handled correctly sparse was unhappy with
the missing annotation as be16_to_cpu() expects a __be16. The __force
cast to __be16 makes sparse happy but has no impact on the generated 
binary.

Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
---

Problem reported by sparse

V2: As requested by Sven Van Asbroeck <thesven73@...il.com> make the
    impact of the patch clear in the commit message.

As far as I understand sparse here the __force is actually the only 
solution possible to inform sparse that the endiannes handling is ok

Patch was compile-tested with. x86_64_defconfig + OF=y, FIELDBUS_DEV=m,
HMS_ANYBUSS_BUS=m

Verification that the patch has no impact on the binary being generated
was done by verifying that the diff of the binaries before and after
applying the patch is empty.


Patch is against 5.1-rc6 (localversion-next is next-20190426)

 drivers/staging/fieldbus/anybuss/host.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/fieldbus/anybuss/host.c b/drivers/staging/fieldbus/anybuss/host.c
index 6227daf..278acac 100644
--- a/drivers/staging/fieldbus/anybuss/host.c
+++ b/drivers/staging/fieldbus/anybuss/host.c
@@ -1348,7 +1348,7 @@ anybuss_host_common_probe(struct device *dev,
 	add_device_randomness(&val, 4);
 	regmap_bulk_read(cd->regmap, REG_FIELDBUS_TYPE, &fieldbus_type,
 			 sizeof(fieldbus_type));
-	fieldbus_type = be16_to_cpu(fieldbus_type);
+	fieldbus_type = be16_to_cpu((__force __be16)fieldbus_type);
 	dev_info(dev, "Fieldbus type: %04X", fieldbus_type);
 	regmap_bulk_read(cd->regmap, REG_MODULE_SW_V, val, 2);
 	dev_info(dev, "Module SW version: %02X%02X",
-- 
2.1.4