On Tue, 7 Oct 2025 13:40:11 -0300
Daniel Almeida <daniel.alme...@collabora.com> wrote:
> > On 7 Oct 2025, at 10:39, Daniel Almeida <daniel.alme...@collabora.com>
> > wrote:
> >
> > Hi Dan, thanks for the review!
> >
> > […]
> >
> >>
> >>> +static void
> >>> +issue_store_multiple(u8 *command_stream, uint64_t kernel_va, uint32_t
> >>> constant)
> >>> +{
> >>> + uint64_t opcode, reg_num, mov48, store_multiple, flush;
> >>> + uint64_t sr, src0, register_bitmap, offset;
> >>> +
> >>> + // MOV48: Load the source register ([r68; r69]) with the
> >>> kernel address
> >>> + opcode = 0x1;
> >>> + reg_num = 68;
> >>> + mov48 = (opcode << 56) | (reg_num << 48) | kernel_va;
> >>> + mov48 = htole64(mov48);
> >>> + memcpy(&command_stream[0], &mov48, sizeof(mov48));
> >>> +
> >>> + // MOV48: Load a known constant into r70
> >>> + opcode = 0x1;
> >>> + reg_num = 70;
> >>> + mov48 = (opcode << 56) | (reg_num << 48) | constant;
> >>> + mov48 = htole64(mov48);
> >>> + memcpy(&command_stream[8], &mov48, sizeof(mov48));
> >>> +
> >>> + // STORE_MULTIPLE: Store the first register to the
> >>> address pointed to by [r68; r69]
> >>> + opcode = 0x15; // STORE_MULTIPLE
> >>> + sr = 70; // Starting from register r70
> >>> + src0 = 68; // Address pointed to by [r68; r69]
> >>> + register_bitmap = 1; // Store the first register
> >>> + offset = 0; // Offset
> >>> + store_multiple = (opcode << 56) | (sr << 48) | (src0 <<
> >>> 40) |
> >>> +
> >>> (register_bitmap << 16) | offset;
> >>> + store_multiple = htole64(store_multiple);
> >>> + memcpy(&command_stream[16], &store_multiple,
> >>> sizeof(store_multiple));
> >>
> >> // MOV48 r68, 0 on the below?
> >
> > Wdym? / Why?
> >
> > I want to clarify what you mean here because it was a bit tricky to get
> > this to
> > work, so I am trying to be really mindful about any changes so that it
> > doesn’t break.
> >
>
> Oh, I now see that you probably also want this to be a comment placed before
> the
> opcode like the FLUSH_CACHES below.
BTW, if we start adding more tests using manually forged command
streams, it might make sense to provides some sort of helpers like
those we have in mesa[1], but let's keep that for later.
[1]https://elixir.bootlin.com/mesa/mesa-25.2.4/source/src/panfrost/genxml/cs_builder.h
