Re: [RFC PATCH v2 1/3] USB: use genalloc for USB HCs with local memory

Laurentiu Tudor
2019-05-15T09:57:18Z

On 14.05.2019 17:42, Christoph Hellwig wrote:
>> @@ -136,6 +137,10 @@ void *hcd_buffer_alloc(
>> if (size <= pool_max[i])
>> return dma_pool_alloc(hcd->pool[i], mem_flags, dma);
>> }
>> +
>> + if (hcd->driver->flags & HCD_LOCAL_MEM)
>> + return gen_pool_dma_alloc(hcd->localmem_pool, size, dma);
>
> I think this check needs to be before the above code to use the dma
> pools, as we should always use the HCD local memory. Probably all the
> way up just below the size == 0 check, that way we can also remove the
> other HCD_LOCAL_MEM check.

Alright.

>> @@ -165,5 +170,10 @@ void hcd_buffer_free(
>> return;
>> }
>> }
>> - dma_free_coherent(hcd->self.sysdev, size, addr, dma);
>> +
>> + if (hcd->driver->flags & HCD_LOCAL_MEM)
>> + gen_pool_free(hcd->localmem_pool, (unsigned long)addr,
>> + size);
>> + else
>> + dma_free_coherent(hcd->self.sysdev, size, addr, dma);
>
> Same here.

Ok.

>> @@ -505,8 +506,15 @@ static int ohci_init (struct ohci_hcd *ohci)
>> timer_setup(&ohci->io_watchdog, io_watchdog_func, 0);
>> ohci->prev_frame_no = IO_WATCHDOG_OFF;
>>
>> - ohci->hcca = dma_alloc_coherent (hcd->self.controller,
>> - sizeof(*ohci->hcca), &ohci->hcca_dma, GFP_KERNEL);
>> + if (hcd->driver->flags & HCD_LOCAL_MEM)
>> + ohci->hcca = gen_pool_dma_alloc(hcd->localmem_pool,
>> + sizeof(*ohci->hcca),
>> + &ohci->hcca_dma);
>> + else
>> + ohci->hcca = dma_alloc_coherent(hcd->self.controller,
>> + sizeof(*ohci->hcca),
>> + &ohci->hcca_dma,
>> + GFP_KERNEL);
>
> I wonder if we could just use hcd_buffer_alloc/free here, althought
> that would require them to be exported. I'll leave that decision to
> the relevant maintainers, though.
>
> Except for this the series looks exactly what I had envisioned to
> get rid of the device local dma_declare_coherent use case, thanks!

Glad I could help. On the remoteproc_virtio.c case, I had a cursory look
and found out that the dma_declare_coherent_memory() usage was
introduced quite recently, by this patch:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=086d08725d34c6b3333db710344ae9c4fdafb2d5

---
Best Regards, Laurentiu