linux-kernel - [PATCH] [RESEND v2] drm/nouveau/clk: fix gcc-7 -Wint-in-bool-context warning

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Date:   Tue, 16 Jan 2018 14:44:50 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Ben Skeggs <bskeggs@...hat.com>
Cc:     Karol Herbst <karolherbst@...il.com>,
        Arnd Bergmann <arnd@...db.de>, David Airlie <airlied@...ux.ie>,
        dri-devel@...ts.freedesktop.org, nouveau@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] [RESEND v2] drm/nouveau/clk: fix gcc-7 -Wint-in-bool-context warning

gcc thinks that interpreting a multiplication result as a bool
is confusing:

drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c: In function 'read_pll':
drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c:133:8: error: '*' in boolean context, suggest '&&' instead [-Werror=int-in-bool-context]

Adding a temporary variable to contain the divisor helps make
it clear what is going on and avoids that warning.

Fixes: 7632b30e4b8b ("drm/nouveau/clk: namespace + nvidia gpu names (no binary change)")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
Originally submitted on July 14, but no reply. Resent on Sep 6, got
one comment and sent an updated version, which again got no other
replies.

This is the v2 version again.

The warning is currently disabled in mainline, but I think we can turn
it back on in the future, and this change here seems harmless.

v2: use a temporary variable as suggested by Karol Herbst.
---
 drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c
index 96e0941c8edd..f0a26881d9b9 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/clk/gt215.c
@@ -110,6 +110,7 @@ read_pll(struct gt215_clk *clk, int idx, u32 pll)
 	struct nvkm_device *device = clk->base.subdev.device;
 	u32 ctrl = nvkm_rd32(device, pll + 0);
 	u32 sclk = 0, P = 1, N = 1, M = 1;
+	u32 MP;
 
 	if (!(ctrl & 0x00000008)) {
 		if (ctrl & 0x00000001) {
@@ -130,10 +131,12 @@ read_pll(struct gt215_clk *clk, int idx, u32 pll)
 		sclk = read_clk(clk, 0x10 + idx, false);
 	}
 
-	if (M * P)
-		return sclk * N / (M * P);
+	MP = M * P;
 
-	return 0;
+	if (!MP)
+		return 0;
+
+	return sclk * N / MP;
 }
 
 static int
-- 
2.9.0