linux-kernel - [PATCH v1] soc: rockchip: power-domain: Fix clang warning about negative shift count

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Date:   Fri, 10 Mar 2017 18:21:53 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Heiko Stuebner <heiko@...ech.de>,
        Elaine Zhang <zhangqing@...k-chips.com>,
        Caesar Wang <wxt@...k-chips.com>,
        Shawn Lin <shawn.lin@...k-chips.com>,
        Douglas Anderson <dianders@...omium.org>,
        Grant Grundler <grundler@...omium.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH v1] soc: rockchip: power-domain: Fix clang warning about negative shift count

The following warning is generated when building with clang:

drivers/soc/rockchip/pm_domains.c:726:22: error: shift count is negative [-Werror,-Wshift-count-negative]
        [RK3399_PD_TCPD0]       = DOMAIN_RK3399(8, 8, -1, false),
                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/soc/rockchip/pm_domains.c:101:2: note: expanded from macro 'DOMAIN_RK3399'
        DOMAIN(pwr, status, req, req, req, wakeup)
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/soc/rockchip/pm_domains.c:88:27: note: expanded from macro 'DOMAIN'
        .req_mask = (req >= 0) ? BIT(req) : 0,          \
                                 ^~~~~~~~
include/linux/bitops.h:6:24: note: expanded from macro 'BIT'

The BIT macro is evaluated with the negative value -1, even though the
resulting value would not be assigned. To fix this we only pass values
between 0 and 63 to BIT(). Unfortunately this means that we lose the
benefit of the compiler checking for out of bounds errors.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 drivers/soc/rockchip/pm_domains.c | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/soc/rockchip/pm_domains.c b/drivers/soc/rockchip/pm_domains.c
index 1c78c42416c6..6f2bb1222992 100644
--- a/drivers/soc/rockchip/pm_domains.c
+++ b/drivers/soc/rockchip/pm_domains.c
@@ -77,13 +77,15 @@ struct rockchip_pmu {
 
 #define to_rockchip_pd(gpd) container_of(gpd, struct rockchip_pm_domain, genpd)
 
+#define RK_MASK(bit) ((bit >= 0) ? BIT(bit & 0x3f) : 0)
+
 #define DOMAIN(pwr, status, req, idle, ack, wakeup)	\
-{						\
-	.pwr_mask = (pwr >= 0) ? BIT(pwr) : 0,		\
-	.status_mask = (status >= 0) ? BIT(status) : 0,	\
-	.req_mask = (req >= 0) ? BIT(req) : 0,		\
-	.idle_mask = (idle >= 0) ? BIT(idle) : 0,	\
-	.ack_mask = (ack >= 0) ? BIT(ack) : 0,		\
+{							\
+	.pwr_mask = RK_MASK(pwr),			\
+	.status_mask = RK_MASK(status),			\
+	.req_mask = RK_MASK(req),			\
+	.idle_mask = RK_MASK(idle),			\
+	.ack_mask = RK_MASK(ack),			\
 	.active_wakeup = wakeup,			\
 }
 
-- 
2.12.0.246.ga2ecc84866-goog