[PATCH] drm/amd/amdgpu: Allow broadcast on debugfs read (v2)

[StDenis, Tom]

It's used by the UMD though they read from 0/*/* when reading the RASTER_CONFIG registers (which may be a bug...)


I only added it because the previous interface was either */*/* or x/y/z (where none are *).  Now it supports arbitrary bank selections.


Tom


________________________________
From: Christian König <deathsimple at vodafone.de>
Sent: Tuesday, October 11, 2016 08:30
To: StDenis, Tom; Michel Dänzer
Cc: amd-gfx at lists.freedesktop.org
Subject: Re: [PATCH] drm/amd/amdgpu: Allow broadcast on debugfs read (v2)

I briefly remember reading in some hardware doc that this actually has a defined behavior.

It was something about applying either bit wise "and" or "or" on the resulting bits and returning that to the reader.

This way you can check with a single broadcast read if an error occurred or if any of the instances are busy.

But if you don't actually use it I suggest to not implement this.

Regards,
Christian.

Am 11.10.2016 um 12:26 schrieb StDenis, Tom:

That actually makes sense.  It came up because mmPA_SC_RASTER_CONFIG (and _1) are read by libdrm with a selection of 0/*/* for se/sh/instance so I wanted to be able to reproduce that via the debugfs interface for testing.


But ya, if you use the broadcast bit who are you reading from then ... hmm..


Tom


________________________________
From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org><mailto:amd-gfx-bounces at lists.freedesktop.org> on behalf of Michel Dänzer <michel.daenzer at mailbox.org><mailto:michel.daenzer at mailbox.org>
Sent: Monday, October 10, 2016 23:52
To: Tom St Denis
Cc: amd-gfx at lists.freedesktop.org<mailto:amd-gfx at lists.freedesktop.org>
Subject: Re: [PATCH] drm/amd/amdgpu: Allow broadcast on debugfs read (v2)

On 09/10/16 08:58 PM, Tom St Denis wrote:
> Allow any of the se/sh/instance fields to be
> specified as a broadcast by submitting 0x3FF.
>
> (v2) Fix broadcast range checking
>
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com><mailto:tom.stdenis at amd.com>

I'm not sure how a "broadcast read" is supposed to work? I can only see
the register specs talking about broadcast in connection with writes.


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