Re: [PATCH 1/2] drm/i915/bdw: Apply workarounds in render ring init function

["Siluvery, Arun" <arun.siluvery@linux.intel.com>]

On 26/08/2014 11:34, Chris Wilson wrote:
> On Tue, Aug 26, 2014 at 11:16:29AM +0100, Siluvery, Arun wrote:
>> On 26/08/2014 11:09, Chris Wilson wrote:
>>> On Tue, Aug 26, 2014 at 10:33:16AM +0100, Arun Siluvery wrote:
>>>> For BDW workarounds are currently initialized in init_clock_gating() but
>>>> they are lost during reset, suspend/resume etc; this patch moves the WAs
>>>> that are part of register state context to render ring init fn otherwise
>>>> default context ends up with incorrect values as they don't get initialized
>>>> until init_clock_gating fn.
>>>>
>>>> v2: Add workarounds to golden render state
>>>> This method has its own issues, first of all this is different for
>>>> each gen and it is generated using a tool so adding new workaround
>>>> and mainitaining them across gens is not a straightforward process.
>>>>
>>>> v3: Use LRIs to emit these workarounds (Ville)
>>>> Instead of modifying the golden render state the same LRIs are
>>>> emitted from within the driver.
>>>>
>>>> For: VIZ-4092
>>>> Signed-off-by: Arun Siluvery <arun.siluvery@linux.intel.com>
>>>> ---
>>>>   drivers/gpu/drm/i915/i915_gem_context.c |  6 +++
>>>>   drivers/gpu/drm/i915/intel_pm.c         | 48 --------------------
>>>>   drivers/gpu/drm/i915/intel_ringbuffer.c | 78 +++++++++++++++++++++++++++++++++
>>>>   drivers/gpu/drm/i915/intel_ringbuffer.h |  1 +
>>>>   4 files changed, 85 insertions(+), 48 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
>>>> index 9683e62..2debce4 100644
>>>> --- a/drivers/gpu/drm/i915/i915_gem_context.c
>>>> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
>>>> @@ -631,20 +631,26 @@ static int do_switch(struct intel_engine_cs *ring,
>>>>   	}
>>>>
>>>>   	uninitialized = !to->legacy_hw_ctx.initialized && from == NULL;
>>>>   	to->legacy_hw_ctx.initialized = true;
>>>>
>>>>   done:
>>>>   	i915_gem_context_reference(to);
>>>>   	ring->last_context = to;
>>>>
>>>>   	if (uninitialized) {
>>>> +		if (IS_BROADWELL(ring->dev)) {
>>>> +			ret = bdw_init_workarounds(ring);
>>>> +			if (ret)
>>>> +				DRM_ERROR("init workarounds: %d\n", ret);
>>>
>>> A good rule of thumb is that if you are exporting gen specific routines,
>>> the layering and abstraction is fishy.
>>> -Chris
>>>
>> ok, so something like i915_init_workarounds() is ok? with a check
>> for bdw/gen8 done inside that function.
>
> Except for init_workarounds is quite useless as a function name and we
> already have a structure that is already customised per-engine and
> per-gen that you could hook into.
> engine->ring_init_context() ?
> -Chris
>

Ok thanks, I can create a new fn ring_init_context().

regards
Arun