Re: [PATCHv9] drm/i915: Added Programming of the MOCS

[Francisco Jerez <currojerez@riseup.net>]

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Damien Lespiau <damien.lespiau@intel.com> writes:

> On Fri, Jul 10, 2015 at 08:13:11PM +0300, Francisco Jerez wrote:
>> From: Peter Antoine <peter.antoine@intel.com>
>> 
>> This change adds the programming of the MOCS registers to the gen 9+
>> platforms. The set of MOCS configuration entries introduced by this
>> patch is intended to be minimal but sufficient to cover the needs of
>> current userspace - i.e. a good set of defaults. It is expected to be
>> extended in the future to provide further default values or to allow
>> userspace to redefine its private MOCS tables based on its demand for
>> additional caching configurations. In this setup, userspace should
>> only utilize the first N entries, higher entries are reserved for
>> future use.
>> 
>> It creates a fixed register set that is programmed across the different
>> engines so that all engines have the same table. This is done as the
>> main RCS context only holds the registers for itself and the shared
>> L3 values. By trying to keep the registers consistent across the
>> different engines it should make the programming for the registers
>> consistent.
>> 
>> v2:
>> -'static const' for private data structures and style changes.(Matt Turner)
>> v3:
>> - Make the tables "slightly" more readable. (Damien Lespiau)
>> - Updated tables fix performance regression.
>> v4:
>> - Code formatting. (Chris Wilson)
>> - re-privatised mocs code. (Daniel Vetter)
>> v5:
>> - Changed the name of a function. (Chris Wilson)
>> v6:
>> - re-based
>> - Added Mesa table entry (skylake & broxton) (Francisco Jerez)
>> - Tidied up the readability defines (Francisco Jerez)
>> - NUMBER of entries defines wrong. (Jim Bish)
>> - Added comments to clear up the meaning of the tables (Jim Bish)
>> 
>> Signed-off-by: Peter Antoine <peter.antoine@intel.com>
>> 
>> v7 (Francisco Jerez):
>> - Don't write L3-specific MOCS_ESC/SCC values into the e/LLC control
>>   tables.  Prefix L3-specific defines consistently with L3_ and
>>   e/LLC-specific defines with LE_ to avoid this kind of confusion in
>>   the future.
>> - Change L3CC WT define back to RESERVED (matches my hardware
>>   documentation and the original patch, probably a misunderstanding
>>   of my own previous comment).
>> - Drop Android tables, define new minimal tables more suitable for the
>>   open source stack.
>> - Add comment that the MOCS tables are part of the kernel ABI.
>> - Move intel_logical_ring_begin() and _advance() calls one level down
>>   (Chris Wilson).
>> - Minor formatting and style fixes.
>> v8 (Francisco Jerez):
>> - Add table size sanity check to emit_mocs_control/l3cc_table() (Chris
>>   Wilson).
>> - Add comment about undefined entries being implicitly set to uncached
>>   for forwards compatibility.
>> v9 (Francisco Jerez):
>> - Minor style fixes.
>
> What's happening here? are we ready to commit to this ABI?

I'm for it.  I also sent a patch for userspace to switch to the new
tables [1] and already have an R-b on it.

[1] http://lists.freedesktop.org/archives/mesa-dev/2015-July/088310.html

>
> -- 
> Damien

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