Re: [Intel-gfx] [PATCH] drm/i915/ddi: Fix i2c_adapter assignment

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 05 Oct 2023, Ville Syrjälä <ville.syrjala@linux.intel.com> wrote:
> On Thu, Oct 05, 2023 at 12:12:58PM +0530, Suraj Kandpal wrote:
>> i2c_adapter is being assigned using intel_connector even before the
>> NULL check occurs and even though it shouldn't be a problem
>> lets just clean this up as logically it does not make sense to check
>> the connector for NULL but dereference it before that.
>> 
>> Fixes: e046d1562491 ("drm/i915/hdmi: Use connector->ddc everwhere")
>> 
>> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
>> ---
>>  drivers/gpu/drm/i915/display/intel_ddi.c | 4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
>> index 4668de45d6fe..6b658faf1fc3 100644
>> --- a/drivers/gpu/drm/i915/display/intel_ddi.c
>> +++ b/drivers/gpu/drm/i915/display/intel_ddi.c
>> @@ -4326,7 +4326,7 @@ static int intel_hdmi_reset_link(struct intel_encoder *encoder,
>>  	struct drm_i915_private *dev_priv = to_i915(encoder->base.dev);
>>  	struct intel_hdmi *hdmi = enc_to_intel_hdmi(encoder);
>>  	struct intel_connector *connector = hdmi->attached_connector;
>> -	struct i2c_adapter *ddc = connector->base.ddc;
>> +	struct i2c_adapter *ddc;
>>  	struct drm_connector_state *conn_state;
>>  	struct intel_crtc_state *crtc_state;
>>  	struct intel_crtc *crtc;
>> @@ -4336,6 +4336,8 @@ static int intel_hdmi_reset_link(struct intel_encoder *encoder,
>>  	if (!connector || connector->base.status != connector_status_connected)
>>  		return 0;
>
> The connector is never NULL here. So the check is just nonsense.

Yeah I'd rather remove that. Leaving it in makes people (and static
analyzers, apprently) think it could be NULL, and that leads to more
what ifs.

BR,
Jani.

>
>>  
>> +	ddc = connector->base.ddc;
>> +
>>  	ret = drm_modeset_lock(&dev_priv->drm.mode_config.connection_mutex,
>>  			       ctx);
>>  	if (ret)
>> -- 
>> 2.25.1

-- 
Jani Nikula, Intel