Patch "drm/tilcdc: ensure nonatomic iowrite64 is not used" has been added to the 4.9-stable tree

Patch "drm/tilcdc: ensure nonatomic iowrite64 is not used" has been added to the 4.9-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    drm/tilcdc: ensure nonatomic iowrite64 is not used

to the 4.9-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-tilcdc-ensure-nonatomic-iowrite64-is-not-used.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Thu Mar 22 14:40:24 CET 2018
From: Logan Gunthorpe <logang@deltatee.com>
Date: Tue, 5 Dec 2017 16:30:51 -0700
Subject: drm/tilcdc: ensure nonatomic iowrite64 is not used

From: Logan Gunthorpe <logang@deltatee.com>


[ Upstream commit 4e5ca2d930aa8714400aedf4bf1dc959cb04280f ]

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 <logang@deltatee.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jyri Sarha <jsarha@ti.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: David Airlie <airlied@linux.ie>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/tilcdc/tilcdc_regs.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/gpu/drm/tilcdc/tilcdc_regs.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_regs.h
@@ -124,7 +124,7 @@ static inline void tilcdc_write64(struct
 	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();


Patches currently in stable-queue which might be from logang@deltatee.com are

queue-4.9/drm-tilcdc-ensure-nonatomic-iowrite64-is-not-used.patch