From: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
To: Daniel Vetter <daniel.vetter@intel.com>,
Jani Nikula <jani.nikula@linux.intel.com>,
intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/1] drm/i915/dsi: silence a warning about uninitialized return value
Date: Sun, 23 Oct 2016 18:55:58 +0200 [thread overview]
Message-ID: <8ebf69c1-2e57-4a67-f392-346d54741826@m4x.org> (raw)
In-Reply-To: <20160904185809.31916-1-nicolas.iooss_linux@m4x.org>
Hello,
I sent the patch below a few weeks ago. I got some comments (cf. [1])
which looked good, but the patch has not been merged in linux-next yet.
Do I need to fix something (like rewrite the commit message) in order to
get it merged?
Thanks,
Nicolas
[1] https://patchwork.freedesktop.org/patch/108941/
On 04/09/16 20:58, Nicolas Iooss wrote:
> When building the kernel with clang and some warning flags, the compiler
> reports that the return value of dcs_get_backlight() may be
> uninitialized:
>
> drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c:53:2: error: variable
> 'data' is used uninitialized whenever 'for' loop exits because its
> condition is false [-Werror,-Wsometimes-uninitialized]
> for_each_dsi_port(port, intel_dsi->dcs_backlight_ports) {
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/intel_dsi.h:126:49: note: expanded from macro
> 'for_each_dsi_port'
> #define for_each_dsi_port(__port, __ports_mask)
> for_each_port_masked(__port, __ports_mask)
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/i915_drv.h:322:26: note: expanded from macro
> 'for_each_port_masked'
> for ((__port) = PORT_A; (__port) < I915_MAX_PORTS; (__port)++) \
> ^~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c:60:9: note:
> uninitialized use occurs here
> return data;
> ^~~~
>
> As intel_dsi->dcs_backlight_ports seems to be always initialized to a
> non-null value, the content of the for loop is always executed and there
> is no bug in the current code. Nevertheless the compiler has no way of
> knowing that assumption, so initialize variable 'data' to silence the
> warning here.
>
> Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
> ---
> drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c b/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c
> index ac7c6020c443..eec45856f910 100644
> --- a/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c
> +++ b/drivers/gpu/drm/i915/intel_dsi_dcs_backlight.c
> @@ -46,7 +46,7 @@ static u32 dcs_get_backlight(struct intel_connector *connector)
> struct intel_encoder *encoder = connector->encoder;
> struct intel_dsi *intel_dsi = enc_to_intel_dsi(&encoder->base);
> struct mipi_dsi_device *dsi_device;
> - u8 data;
> + u8 data = 0;
> enum port port;
>
> /* FIXME: Need to take care of 16 bit brightness level */
>
next prev parent reply other threads:[~2016-10-23 16:56 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-04 18:58 [PATCH 1/1] drm/i915/dsi: silence a warning about uninitialized return value Nicolas Iooss
2016-09-06 10:21 ` [Intel-gfx] " Dave Gordon
2016-09-06 20:36 ` Nicolas Iooss
2016-09-07 16:03 ` Dave Gordon
2016-09-07 23:02 ` Nicolas Iooss
2016-09-08 14:31 ` Dave Gordon
2016-09-11 21:16 ` Nicolas Iooss
2016-10-23 16:55 ` Nicolas Iooss [this message]
2016-10-23 17:22 ` Chris Wilson
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