[Intel-gfx] [PATCH] drm/i915: Initialise outparam for error return from wait_for_register

[Souza, Jose]

On Wed, 2020-08-19 at 12:54 +0100, Chris Wilson wrote:
> Just in case the caller passes in 0 for both slow&fast timeouts, make
> sure we initialise the stack value returned. Add an assert so that we
> don't make the mistake of passing 0 timeouts for the wait.
> 
> drivers/gpu/drm/i915/intel_uncore.c:2011 __intel_wait_for_register_fw() error: uninitialized symbol 'reg_value'.
> 

Reviewed-by: José Roberto de Souza <jose.souza at intel.com>

> References: 3f649ab728cd ("treewide: Remove uninitialized_var() usage")
> Signed-off-by: Chris Wilson <
> chris at chris-wilson.co.uk
> >
> ---
>  drivers/gpu/drm/i915/intel_uncore.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
> index 8d5a933e6af6..263ffcb832b7 100644
> --- a/drivers/gpu/drm/i915/intel_uncore.c
> +++ b/drivers/gpu/drm/i915/intel_uncore.c
> @@ -1993,13 +1993,14 @@ int __intel_wait_for_register_fw(struct intel_uncore *uncore,
>  				 unsigned int slow_timeout_ms,
>  				 u32 *out_value)
>  {
> -	u32 reg_value;
> +	u32 reg_value = 0;
>  #define done (((reg_value = intel_uncore_read_fw(uncore, reg)) & mask) == value)
>  	int ret;
>  
>  	/* Catch any overuse of this function */
>  	might_sleep_if(slow_timeout_ms);
>  	GEM_BUG_ON(fast_timeout_us > 20000);
> +	GEM_BUG_ON(!fast_timeout_us && !slow_timeout_ms);
>  
>  	ret = -ETIMEDOUT;
>  	if (fast_timeout_us && fast_timeout_us <= 20000)
>