[Intel-gfx] [PATCH 5/8] drm/i915: Introduce iterators for execlist ports

[Chris Wilson]

Quoting Mika Kuoppala (2017-09-12 09:36:15)
> Switch to iterators for execlist_port access. This is
> a preparation for indexing ports from arbitrary location. Which
> in turn allows us to handle ports in ring like fashion.
> 
> Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>

Something we want to keep an eye as we switch to these macros is code
generation. As a quick guide, check object size, i.e. run
scripts/bloat-o-meter.

> -static inline unsigned int
> -execlist_num_ports(const struct intel_engine_execlist * const el)
> -{
> -       return el->port_mask + 1;
> -}
> +/* Iterators over elsp ports */
> +#define __port_idx(start, i, m) (((start) + (i)) & (m))
> +
> +#define for_each_execlist_port(el__, port__, n__) \
> +       for ((n__) = 0; \
> +            (port__) = &(el__)->port[__port_idx(0, (n__), (el__)->port_mask)], (n__) < (el__)->port_mask + 1; \
> +            (n__)++)

Using (n__) is misleading. It can't be anything other than a lhv (i.e.
plain variable and not an expr). checkpatch can complain all it wants.

Probably should keep execlist_num_ports() for another patch.
That x < y + 1 just keeps on triggering me everytime I see it.

> +
> +#define for_each_execlist_port_reverse(el__, port__, n__) \
> +       for ((n__) = (el__)->port_mask + 1; \
> +            (port__) = &(el__)->port[__port_idx((el__)->port_mask, (n__), (el__)->port_mask)], (n__)--;)
>  
>  static inline void
>  execlist_port_complete(struct intel_engine_execlist * const el,