[RFC,libdrm 1/3] tegra: Add stream library

[Mark Zhang]

I just skimmed the code of libdrm while I'm trying to understand the
host1x driver. So below is what I found.

Mark
On 12/13/2012 10:01 PM, Arto Meriläinen wrote:
> From: Arto Merilainen <amerilainen at nvidia.com>
> 
> This patch introduces tegra stream library. The library is used for
> buffer management, command stream construction and work
> synchronization.
> 
[...]
> +
> +/*
> + * tegra_fence_is_valid(fence)
> + *
> + * Check validity of a fence. We just check that the fence range
> + * is valid w.r.t. host1x hardware.
> + */
> +
> +int tegra_fence_is_valid(const struct tegra_fence *fence)
> +{
> +    int valid = fence ? 1 : 0;
> +    valid = valid && fence->id != (uint32_t) -1;
> +    valid = valid && fence->id < 32;

Hardcode here. Assume always has 32 syncpts.
Change to a micro wrapped with tegra version ifdef will be better.

> +    return valid;
> +}
> +
[...]
> +
> +    /* Add fences */
> +    if (num_fences) {
> +
> +        tegra_stream_push(stream,
> +            nvhost_opcode_setclass(NV_HOST1X_CLASS_ID,
> +            host1x_uclass_wait_syncpt_r(), num_fences));
> +
> +        for (; num_fences; num_fences--, fence++) {
> +            assert(tegra_fence_is_valid(fence));

This is useless. We already add "1 + num_fences" to num_words above. So
move this "assert" before adding "1 + num_fences" to num_words makes sense.

> +
> +            tegra_stream_push(stream, nvhost_class_host_wait_syncpt(fence->id,
> +                fence->value));
> +        }
> +    }
> +
> +    if (class_id)
> +        tegra_stream_push(stream, nvhost_opcode_setclass(class_id, 0, 0));
> +
> +    return 0;
> +}
> +
[...]
> +
> +#endif /* TEGRA_DRMIF_H */
>