On Tue, 27 May 2014, Daniel Vetter <daniel@xxxxxxxx> wrote:
> On Tue, May 27, 2014 at 07:24:12PM +0300, Jani Nikula wrote:
>> If both KMS is disabled (by i915.modeset=0 or nomodeset parameters) and
>> UMS is disabled (by CONFIG_DRM_I915_UMS=n, the default), the user might
>> not be aware his setup is not supported. Inform the users (and, by
>> extension, the poor i915 developers having to read their dmesgs in bug
>> reports) why their graphics experience might be lacking.
>>
>> A similar message was added on the UMS path in
>> commit e147accbd19f55489dabdcc4dc3551cc3e3f2553
>> Author: Jani Nikula <jani.nikula@xxxxxxxxx>
>> Date: Thu Oct 10 15:25:37 2013 +0300
>>
>> drm/i915: tell the user KMS is required for gen6+
>>
>> but it won't be reached if CONFIG_DRM_I915_UMS=n since
>> commit b30324adaf8d2e5950a602bde63030d15a61826f
>> Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
>> Date: Wed Nov 13 22:11:25 2013 +0100
>>
>> drm/i915: Deprecated UMS support
>>
>> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
>
> Hm, the idea is that this fails _very_ silently so that people only send
> us regression reports if they actually notice something. Since if there
> are still people out there which needs UMS, we can't yet rip it out.
My gut feeling from bug reports is that, since CONFIG_DRM_I915_UMS now
defaults to n, we mostly end up here because users have issues with KMS
and try nomodeset as a workaround. Is this silent enough, same commit
message:
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 8949fd26b0ea..ca46e6cf4b99 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1585,6 +1585,7 @@ static int __init i915_init(void)
driver.get_vblank_timestamp = NULL;
#ifndef CONFIG_DRM_I915_UMS
/* Silently fail loading to not upset userspace. */
+ DRM_DEBUG_DRIVER("KMS and UMS disabled.\n");
return 0;
#endif
}
BR,
Jani.
> -Daniel
>
>> ---
>> drivers/gpu/drm/i915/i915_drv.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
>> index 8949fd26b0ea..f0f690776d45 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.c
>> +++ b/drivers/gpu/drm/i915/i915_drv.c
>> @@ -1584,6 +1584,8 @@ static int __init i915_init(void)
>> if (!(driver.driver_features & DRIVER_MODESET)) {
>> driver.get_vblank_timestamp = NULL;
>> #ifndef CONFIG_DRM_I915_UMS
>> + DRM_INFO("Kernel modesetting (KMS) and userspace modesetting (UMS) disabled\n");
>> + DRM_INFO("See CONFIG_DRM_I915_UMS, CONFIG_DRM_I915_KMS, nomodeset, and i915.modeset parameters\n");
>> /* Silently fail loading to not upset userspace. */
>> return 0;
>> #endif
>> --
>> 1.9.1
>>
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>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
--
Jani Nikula, Intel Open Source Technology Center
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