[Intel-gfx] [PATCH] drm/i915: Squeeze iommu status into debugfs/i915_capabilities

[Martin Peres]

On 11/09/2019 14:46, Chris Wilson wrote:
> There's no easy way of checking whether iommu is enabled for the GPU
> (you can grep dmesg if you know the device, or you can grep
> i915_gpu_info if that's available). We do have a central
> i915_capabilities with the intent of listing such pertinent information,
> so add the iommu status.
> 
> Suggested-by: Martin Peres <martin.peres at linux.intel.com>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Martin Peres <martin.peres at linux.intel.com>
> Cc: Tomi Sarvela <tomi.p.sarvela at intel.com>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/i915_debugfs.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 708855e051b5..e5835337f022 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -61,11 +61,18 @@ static int i915_capabilities(struct seq_file *m, void *data)
>  	struct drm_i915_private *dev_priv = node_to_i915(m->private);
>  	const struct intel_device_info *info = INTEL_INFO(dev_priv);
>  	struct drm_printer p = drm_seq_file_printer(m);
> +	const char *msg;
>  
>  	seq_printf(m, "gen: %d\n", INTEL_GEN(dev_priv));
>  	seq_printf(m, "platform: %s\n", intel_platform_name(info->platform));
>  	seq_printf(m, "pch: %d\n", INTEL_PCH_TYPE(dev_priv));
>  
> +	msg = "n/a";

Here, "n/a" really means "kernel not compiled with IOMMU support".
Should we find a wording better explaining this to users? Or are we
going to tell users to check their dmesg for IOMMU messages and if there
are none, it means either the kernel has not been compiled with support
for it, or an option needs to be enabled in the bios, or the platform
lacks support?

Anyway, thanks!

Acked-by: Martin Peres <martin.peres at linux.intel.com>

> +#ifdef CONFIG_INTEL_IOMMU
> +	msg = enableddisabled(intel_iommu_gfx_mapped);
> +#endif
> +	seq_printf(m, "iommu: %s\n", msg);
> +
>  	intel_device_info_dump_flags(info, &p);
>  	intel_device_info_dump_runtime(RUNTIME_INFO(dev_priv), &p);
>  	intel_driver_caps_print(&dev_priv->caps, &p);
>