On Saturday, June 24, 2023 10:17:57 AM PDT Lucas De Marchi wrote: > The comment on the parameter being 0 to avoid the read back doesn't > apply as this is not a call to wa_mcr_add(), but rather to > wa_mcr_clr_set(). So, this register is actually checked and it's > according to the Bspec that the register is RW, not RO. I think you mean wa_add and wa_write_clr_set here (not mcr). One thing I've been confused about while reading this code: static void wa_write_clr_set(struct i915_wa_list *wal, i915_reg_t reg, u32 clear, u32 set) { wa_add(wal, reg, clear, set, clear, false); } The second to last parameter is read_mask aka wa->read. We're initializing it to the...bits to clear. (I would think it should be (clear | set) to pick up all modified bits.) wa_verify seems to balk at ((cur ^ wa->set) & wa->read). But...if wa->read is just the clear mask, that wouldn't actually verify that any bits were set at all. Or am I misunderstanding something? If not, we may be failing to verify the majority of our workarounds :( > Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> > --- > drivers/gpu/drm/i915/gt/intel_workarounds.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c > index 848519b58e45..5fe85fad91c1 100644 > --- a/drivers/gpu/drm/i915/gt/intel_workarounds.c > +++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c > @@ -666,7 +666,7 @@ static void icl_ctx_workarounds_init(struct intel_engine_cs *engine, > /* Wa_1604278689:icl,ehl */ > wa_write(wal, IVB_FBC_RT_BASE, 0xFFFFFFFF & ~ILK_FBC_RT_VALID); > wa_write_clr_set(wal, IVB_FBC_RT_BASE_UPPER, > - 0, /* write-only register; skip validation */ > + 0, > 0xFFFFFFFF); > > /* Wa_1406306137:icl,ehl */ In this particular example, since clear bits are 0, I don't think any verification is happening at all. --Ken
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