[Intel-gfx] [PATCH 06/17] drm/i915: Move {pin, long}_mask initialization to caller from intel_get_hpd_pins()

[Paulo Zanoni]

2015-08-27 17:56 GMT-03:00  <ville.syrjala at linux.intel.com>:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Move the 0 initialization of pin_mask and long_mask from
> intel_get_hpd_pins() into each caller. This we we can call
> intel_get_hpd_pins() multiple times to accumulate more pins from several
> sources.

Hmm... I'm not a big fan of this approach since it makes the code more
dangerous. I wouldn't be surprised if next year we discover that the
code for the next hardware generation forgot to zero-initialize the
variables. You know, programmers from the future are always really
bad.

You could at least write a small comment at the top of
intel_get_hpd_pins() telling the callers to clear their masks first.

I would still prefer my original suggestion of having 2 variables for
people who call this twice, but this one is correct, so:
Reviewed-by: Paulo Zanoni <paulo.r.zanoni at intel.com>

>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_irq.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index 3388b64..db27945 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1301,9 +1301,6 @@ static void intel_get_hpd_pins(u32 *pin_mask, u32 *long_mask,
>         enum port port;
>         int i;
>
> -       *pin_mask = 0;
> -       *long_mask = 0;
> -
>         for_each_hpd_pin(i) {
>                 if ((hpd[i] & hotplug_trigger) == 0)
>                         continue;
> @@ -1544,7 +1541,7 @@ static void i9xx_hpd_irq_handler(struct drm_device *dev)
>  {
>         struct drm_i915_private *dev_priv = dev->dev_private;
>         u32 hotplug_status = I915_READ(PORT_HOTPLUG_STAT);
> -       u32 pin_mask, long_mask;
> +       u32 pin_mask = 0, long_mask = 0;
>
>         if (!hotplug_status)
>                 return;
> @@ -1673,7 +1670,7 @@ static void ibx_irq_handler(struct drm_device *dev, u32 pch_iir)
>         u32 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK;
>
>         if (hotplug_trigger) {
> -               u32 dig_hotplug_reg, pin_mask, long_mask;
> +               u32 dig_hotplug_reg, pin_mask = 0, long_mask = 0;
>
>                 dig_hotplug_reg = I915_READ(PCH_PORT_HOTPLUG);
>                 I915_WRITE(PCH_PORT_HOTPLUG, dig_hotplug_reg);
> @@ -1781,7 +1778,7 @@ static void cpt_irq_handler(struct drm_device *dev, u32 pch_iir)
>                 hotplug_trigger = pch_iir & SDE_HOTPLUG_MASK_CPT;
>
>         if (hotplug_trigger) {
> -               u32 dig_hotplug_reg, pin_mask, long_mask;
> +               u32 dig_hotplug_reg, pin_mask = 0, long_mask = 0;
>
>                 dig_hotplug_reg = I915_READ(PCH_PORT_HOTPLUG);
>                 I915_WRITE(PCH_PORT_HOTPLUG, dig_hotplug_reg);
> @@ -2004,7 +2001,7 @@ static void bxt_hpd_handler(struct drm_device *dev, uint32_t iir_status)
>  {
>         struct drm_i915_private *dev_priv = dev->dev_private;
>         u32 hp_control, hp_trigger;
> -       u32 pin_mask, long_mask;
> +       u32 pin_mask = 0, long_mask = 0;
>
>         /* Get the status */
>         hp_trigger = iir_status & BXT_DE_PORT_HOTPLUG_MASK;
> --
> 2.4.6
>
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-- 
Paulo Zanoni