[PATCH 2/2] drm/i915/gvt: implement override and restore call back for GFX_MODE

[Dong, Chuanxiao]

> -----Original Message-----
> From: Tian, Kevin
> Sent: Tuesday, February 28, 2017 10:49 AM
> To: Dong, Chuanxiao <chuanxiao.dong at intel.com>; intel-gvt-
> dev at lists.freedesktop.org
> Subject: RE: [PATCH 2/2] drm/i915/gvt: implement override and restore call
> back for GFX_MODE
> 
> > From: Chuanxiao Dong
> > Sent: Monday, February 27, 2017 5:38 PM
> >
> > When host and guest are using different ring submission, host cannot
> > use the GFX_MODE register value from guest. So implement the override
> > and restore call backs to handle GFX_MODE properly
> 
> I feel it might be an overkill to develop a new framework here. In reality I
> expect only a few mode registers which we may need special handling.
> Then explicitly handling them in one place at end of mmio restoring results
> less code and more readability.

Embed the GFX_MODE override/restore in the load/restore function is also an option. Actually I am not sure if in future whether other MMIO has similar requirement or not, so added restore/load callback to give more flexibility for the each MMIO. Different MMIO can have different handling. If this is not necessary, I will change the implementation.

> 
> >
> > Signed-off-by: Chuanxiao Dong <chuanxiao.dong at intel.com>
> > ---
> >  drivers/gpu/drm/i915/gvt/render.c | 74
> > ++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 70 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gvt/render.c
> > b/drivers/gpu/drm/i915/gvt/render.c
> > index 7997d70..11f2507 100644
> > --- a/drivers/gpu/drm/i915/gvt/render.c
> > +++ b/drivers/gpu/drm/i915/gvt/render.c
> > @@ -48,8 +48,68 @@ struct render_mmio {
> >  	u32 original_bits;
> >  };
> >
> > +static void render_mmio_override(struct render_mmio *mmio,
> > +		u32 *v, u32 mask, u32 override_bits) {
> > +	u32 temp_v = *v;
> > +
> > +	if ((temp_v & mask) == override_bits) {
> > +		mmio->override_mask = 0;
> > +		mmio->original_bits = 0;
> > +		return;
> > +	}
> > +
> > +	/* record which bits are changed */
> > +	mmio->original_bits = temp_v & mask;
> > +	mmio->override_mask = mask;
> > +
> > +	/* set the new value */
> > +	temp_v &= ~mask;
> > +	*v = (temp_v | override_bits);
> > +}
> > +
> > +static void render_mmio_override_gfx_mode(struct render_mmio *mmio,
> > +u32 *v) {
> > +	u32 mask, override_bits;
> > +
> > +	if (!v || !mmio)
> > +		return;
> > +
> > +	if (i915.enable_guc_submission) {
> > +		mask = GFX_FORWARD_VBLANK_MASK |
> GFX_INTERRUPT_STEERING;
> > +		override_bits = GFX_FORWARD_VBLANK_NEVER |
> > +			GFX_INTERRUPT_STEERING;
> > +	} else {
> > +		mask = GFX_INTERRUPT_STEERING;
> > +		override_bits = 0;
> > +	}
> > +
> > +	render_mmio_override(mmio, v, mask, override_bits); }
> > +
> > +static void render_mmio_restore(struct render_mmio *mmio, u32 *v) {
> > +	u32 temp_v;
> > +
> > +	if (!v || !mmio || !mmio->override_mask)
> > +		return;
> > +
> > +	/*
> > +	 * remove the host override bits and
> > +	 * restore back the guest mmio
> > +	 */
> > +	temp_v = *v;
> > +	temp_v &= ~mmio->override_mask;
> > +	*v = temp_v | mmio->original_bits;
> > +
> > +	mmio->override_mask = 0;
> > +	mmio->original_bits = 0;
> > +}
> > +
> >  static struct render_mmio gen8_render_mmio_list[] = {
> > -	{RCS, _MMIO(0x229c), 0xffff, false},
> > +	{RCS, _MMIO(0x229c), 0xffff, false,
> > +		render_mmio_override_gfx_mode,
> > +		render_mmio_restore},
> >  	{RCS, _MMIO(0x2248), 0x0, false},
> >  	{RCS, _MMIO(0x2098), 0x0, false},
> >  	{RCS, _MMIO(0x20c0), 0xffff, true},
> > @@ -72,7 +132,9 @@ static struct render_mmio gen8_render_mmio_list[]
> = {
> >  	{RCS, _MMIO(0x7300), 0xffff, true},
> >  	{RCS, _MMIO(0x83a4), 0xffff, true},
> >
> > -	{BCS, _MMIO(0x2229c), 0xffff, false},
> > +	{BCS, _MMIO(0x2229c), 0xffff, false,
> > +		render_mmio_override_gfx_mode,
> > +		render_mmio_restore},
> >  	{BCS, _MMIO(0x2209c), 0xffff, false},
> >  	{BCS, _MMIO(0x220c0), 0xffff, false},
> >  	{BCS, _MMIO(0x22098), 0x0, false},
> > @@ -80,7 +142,9 @@ static struct render_mmio gen8_render_mmio_list[]
> =
> > {  };
> >
> >  static struct render_mmio gen9_render_mmio_list[] = {
> > -	{RCS, _MMIO(0x229c), 0xffff, false},
> > +	{RCS, _MMIO(0x229c), 0xffff, false,
> > +		render_mmio_override_gfx_mode,
> > +		render_mmio_restore},
> >  	{RCS, _MMIO(0x2248), 0x0, false},
> >  	{RCS, _MMIO(0x2098), 0x0, false},
> >  	{RCS, _MMIO(0x20c0), 0xffff, true},
> > @@ -121,7 +185,9 @@ static struct render_mmio gen9_render_mmio_list[]
> = {
> >  	{RCS, _MMIO(0x4df0), 0, false},
> >  	{RCS, _MMIO(0x4df4), 0, false},
> >
> > -	{BCS, _MMIO(0x2229c), 0xffff, false},
> > +	{BCS, _MMIO(0x2229c), 0xffff, false,
> > +		render_mmio_override_gfx_mode,
> > +		render_mmio_restore},
> >  	{BCS, _MMIO(0x2209c), 0xffff, false},
> >  	{BCS, _MMIO(0x220c0), 0xffff, false},
> >  	{BCS, _MMIO(0x22098), 0x0, false},
> > --
> > 2.7.4
> >
> >
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