From: Logan Gunthorpe Subject: [PATCH v6 1/7] drm/tilcdc: ensure nonatomic iowrite64 is not used Date: Thu, 3 Aug 2017 12:30:12 -0600 Message-ID: <20170803183018.5889-2-logang@deltatee.com> References: <20170803183018.5889-1-logang@deltatee.com> Cc: Arnd Bergmann , Greg Kroah-Hartman , Andy Shevchenko , =?UTF-8?q?Horia=20Geant=C4=83?= , Stephen Bates , Logan Gunthorpe , Jyri Sarha , Tomi Valkeinen , David Airlie To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-ntb@googlegroups.com, linux-crypto@vger.kernel.org Return-path: In-Reply-To: <20170803183018.5889-1-logang@deltatee.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Add a check to ensure iowrite64 is only used if it is atomic. It was decided in [1] that the tilcdc driver should not be using an atomic operation (so it was left out of this patchset). However, it turns out that through the drm code, a nonatomic header is actually included: include/linux/io-64-nonatomic-lo-hi.h is included from include/drm/drm_os_linux.h:9:0, from include/drm/drmP.h:74, from include/drm/drm_modeset_helper.h:26, from include/drm/drm_atomic_helper.h:33, from drivers/gpu/drm/tilcdc/tilcdc_crtc.c:19: And thus, without this change, this patchset would inadvertantly change the behaviour of the tilcdc driver. [1] lkml.kernel.org/r/CAK8P3a2HhO_zCnsTzq7hmWSz5La5Thu19FWZpun16iMnyyNreQ@mail.gmail.com Signed-off-by: Logan Gunthorpe Cc: Jyri Sarha Cc: Arnd Bergmann Cc: Tomi Valkeinen Cc: David Airlie --- drivers/gpu/drm/tilcdc/tilcdc_regs.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/tilcdc/tilcdc_regs.h b/drivers/gpu/drm/tilcdc/tilcdc_regs.h index 9d528c0a67a4..5048ebb86835 100644 --- a/drivers/gpu/drm/tilcdc/tilcdc_regs.h +++ b/drivers/gpu/drm/tilcdc/tilcdc_regs.h @@ -133,7 +133,7 @@ static inline void tilcdc_write64(struct drm_device *dev, u32 reg, u64 data) struct tilcdc_drm_private *priv = dev->dev_private; volatile void __iomem *addr = priv->mmio + reg; -#ifdef iowrite64 +#if defined(iowrite64) && !defined(iowrite64_is_nonatomic) iowrite64(data, addr); #else __iowmb(); -- 2.11.0