From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Date: Thu, 13 Oct 2016 12:13:11 +0000 Subject: Re: [patch] drm/i915: fix a read size argument Message-Id: <87zim8wip4.fsf@intel.com> List-Id: References: <20161013085508.GJ16198@mwanda> <57FF5380.1080704@bfs.de> In-Reply-To: <57FF5380.1080704@bfs.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: wharms@bfs.de, Dan Carpenter Cc: intel-gfx@lists.freedesktop.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, drm-intel-fixes@lists.freedesktop.org, Daniel Vetter On Thu, 13 Oct 2016, walter harms wrote: > Am 13.10.2016 10:55, schrieb Dan Carpenter: >> We want to read 3 bytes here, but because the parenthesis are in the >> wrong place we instead read: >> >> sizeof(intel_dp->edp_dpcd) = sizeof(intel_dp->edp_dpcd) >> >> which is one byte. >> >> Fixes: fe5a66f91c88 ("drm/i915: Read PSR caps/intermediate freqs/etc. only once on eDP") >> Signed-off-by: Dan Carpenter Dan, good catch, thank you. Luckily we only really use the first byte currently... Cc: >> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c >> index 14a3cf0..ee8aa95 100644 >> --- a/drivers/gpu/drm/i915/intel_dp.c >> +++ b/drivers/gpu/drm/i915/intel_dp.c >> @@ -3551,8 +3551,8 @@ intel_edp_init_dpcd(struct intel_dp *intel_dp) >> /* Read the eDP Display control capabilities registers */ >> if ((intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & DP_DPCD_DISPLAY_CONTROL_CAPABLE) && >> drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV, >> - intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd) = >> - sizeof(intel_dp->edp_dpcd))) >> + intel_dp->edp_dpcd, sizeof(intel_dp->edp_dpcd)) = >> + sizeof(intel_dp->edp_dpcd)) > > > > perhaps we can morph that into something more readable ? I would suggest: > > > if (intel_dp->dpcd[DP_EDP_CONFIGURATION_CAP] & DP_DPCD_DISPLAY_CONTROL_CAPABLE) > { > size_t size=sizeof(intel_dp->edp_dpcd); /* = EDP_DISPLAY_CTL_CAP_SIZE */ > int ret; > > ret=drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_DPCD_REV,intel_dp->edp_dpcd,size); > > if (ret != size ) > ...... > > } > > this way it improves readability and reduces line length. Not convinced, let's just take the simple brace fix now. BR, Jani. -- Jani Nikula, Intel Open Source Technology Center