Re: [PATCH v2 1/9] drivers/char: Add support for Xue USB3 debugger

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Thu, Jul 14, 2022 at 01:58:25PM +0200, Jan Beulich wrote:
> On 06.07.2022 17:32, Marek Marczykowski-Górecki wrote:
> > +static int xue_init_dbc(struct xue *xue)
> > +{
> > +    uint64_t erdp = 0;
> > +    uint64_t out = 0;
> > +    uint64_t in = 0;
> > +    uint64_t mbs = 0;
> > +    struct xue_dbc_reg *reg = xue_find_dbc(xue);
> > +
> > +    if ( !reg )
> > +        return 0;
> > +
> > +    xue->dbc_reg = reg;
> > +    xue_disable_dbc(xue);
> > +
> > +    xue_trb_ring_init(xue, &xue->dbc_ering, 0, XUE_DB_INVAL);
> > +    xue_trb_ring_init(xue, &xue->dbc_oring, 1, XUE_DB_OUT);
> > +    xue_trb_ring_init(xue, &xue->dbc_iring, 1, XUE_DB_IN);
> > +
> > +    erdp = virt_to_maddr(xue->dbc_ering.trb);
> > +    if ( !erdp )
> > +        return 0;
> > +
> > +    memset(xue->dbc_erst, 0, sizeof(*xue->dbc_erst));
> > +    xue->dbc_erst->base = erdp;
> > +    xue->dbc_erst->size = XUE_TRB_RING_CAP;
> > +
> > +    mbs = (reg->ctrl & 0xFF0000) >> 16;
> > +    out = virt_to_maddr(xue->dbc_oring.trb);
> > +    in = virt_to_maddr(xue->dbc_iring.trb);
> > +
> > +    memset(xue->dbc_ctx, 0, sizeof(*xue->dbc_ctx));
> > +    xue_init_strings(xue, xue->dbc_ctx->info);
> > +    xue_init_ep(xue->dbc_ctx->ep_out, mbs, xue_ep_bulk_out, out);
> > +    xue_init_ep(xue->dbc_ctx->ep_in, mbs, xue_ep_bulk_in, in);
> > +
> > +    reg->erstsz = 1;
> > +    reg->erstba = virt_to_maddr(xue->dbc_erst);
> > +    reg->erdp = erdp;
> > +    reg->cp = virt_to_maddr(xue->dbc_ctx);
> 
> The only place this field is read looks to be xue_dump().

No, reg is MMIO, all those assignments are actually configuring the
device.

-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab

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