[PATCH V2 1/3] drm/xe: Move enable host l2 VRAM post MCR init

[Lucas De Marchi]

On Wed, Aug 14, 2024 at 12:23:45PM GMT, Matt Roper wrote:
>On Wed, Aug 14, 2024 at 11:34:21AM -0500, Lucas De Marchi wrote:
>> On Wed, Aug 14, 2024 at 03:26:12PM GMT, Tejas Upadhyay wrote:
>> > enable host l2 VRAM is reading MCR register thus
>> > should be moved after MCR init is done.
>>
>> This commit message skips a lot of the details on what was discussed in
>> the other thread. Let's improve it and for future please be more verbose
>> in your commit messages. Suggestion:
>>
>> 	xe_gt_enable_host_l2_vram() is reading the XE2_GAMREQSTRM_CTRL register
>> 	that is currently missing the MCR annotation. However, just adding the
>> 	annotation doesn't work as this function is called before MCR handling
>> 	is initialized in xe_gt_mcr_init().
>>
>> 	xe_gt_enable_host_l2_vram() is used to implement WA 16023588340 that
>> 	needs to be done as early as possible during initialization in order
>> 	to be effective since the MMIO writes impact it. In the failure
>> 	scenario, driver would simply not be able to bind sucesfully.
>>
>> 	Moving xe_gt_enable_host_l2_vram() later, after MCR initialization is
>> 	done, only incurs a few additional HW accesses, particularly when
>> 	loading GuC for hwconfig. Binding/unbinding the driver 100 times in
>> 	BMG still works so it should be ok to start handling the WA a little
>> 	bit later. This is sufficient to allow adding the MCR annotation to
>> 	XE2_GAMREQSTRM_CTRL.
>>
>> >
>> > V2(Matt):
>> > - Reword commit message
>> > V1(Lucas):
>> > - Reorder patch and reorder flow of L2 VRAM enable
>> >
>> > Cc: Lucas De Marchi <lucas.demarchi at intel.com>
>> > Signed-off-by: Tejas Upadhyay <tejas.upadhyay at intel.com>
>>
>> Matt Roper / Matthew Auld, do the paragraphs above capture
>> correctly the discussion we had in the previous version?
>
>Yeah, that expanded description looks good to me.  With that,
>
>        Reviewed-by: Matt Roper <matthew.d.roper at intel.com>

pushed to drm-xe-next, thanks

Lucas De Marchi