Às 3:52 PM de 3/23/2017, Marc Zyngier escreveu:
> On 23/03/17 15:22, Joao Pinto wrote:
>> Hi Mark,
>>
>> Às 10:41 AM de 3/21/2017, Marc Zyngier escreveu:
>>> On 21/03/17 10:27, Joao Pinto wrote:
>>>>
>>>> Hi Mark,
>>>>
>>>> Às 6:16 PM de 3/20/2017, Marc Zyngier escreveu:
>>>>> Hi Joao,
>>>>>
>>>>> On 20/03/17 17:30, Joao Pinto wrote:
>>>>>> Hi Mark,
>>>>>>
>>> A very simple example using the current API is pcie-altera-msi.c (some
>>> others are much more intricate), and should give you a good picture of
>>> how PCI/MSI, generic MSI and MSI controllers interact.
>>>
>>> Start with understanding how the various layers interact via their own
>>> IRQ domains, and implement their own IRQ chip. Happy to answer questions
>>> (I'm sure you'll have some).
>>>
>>> Thanks,
>>>
>>> M.
>>
>> I have one quick question... What address should I configure in vector_phy?
>> is this needed in pcie-designware?
>
> You may be in a better place than me to answer that question! ;-)
>
> If I remember well, the Altera RC needs to be programmed with the
> address of the MSI doorbell so that it can detect the end-point writes
> to it, and it can be anything you want. In order not to waste any memory
> space, we use the base address of the RC.
>
> Both very nice and dead ugly, if you want my opinion.
>
> If we look at this:
>
> void dw_pcie_msi_init(struct pcie_port *pp)
> {
> u64 msi_target;
>
> pp->msi_data = __get_free_pages(GFP_KERNEL, 0);
> msi_target = virt_to_phys((void *)pp->msi_data);
>
> /* program the msi_data */
> dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_LO, 4,
> (u32)(msi_target & 0xffffffff));
> dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_HI, 4,
> (u32)(msi_target >> 32 & 0xffffffff));
> }
>
> We can infer the Designware IP has a similar behaviour, except that it
> wastes a page of RAM for no obvious reason. It'd be good to know if the
> RC actually propagates the write to the memory. If it really does, then
> that's the only way to do it. If it doesn't, then the Altera method is
> much better...
Thanks for the help, I am not very familar with the MSI mechanism, so still
giving baby steps :) Yes, for now I am using "pp->msi_data =
__get_free_pages(GFP_KERNEL, 0);". Thanks for the tip!
>
> Hope this helps,
>
> M.
>
