On Wed, Mar 29, 2017 at 11:06:53AM +0300, Felipe Balbi wrote:
>
> Hi,
>
> Peter Chen <hzpeterchen@xxxxxxxxx> writes:
> >> > According to xHCI ch4.20 Scratchpad Buffers
> >> > A Scratchpad Buffer is a PAGESIZE block of system memory
> >> > located on a PAGESIZE boundary
> >> > ...
> >> > Software clears the Scratchpad Buffer to ‘0’
> >> >
> >> > So, we need to use dma pool for PAGESIZE boundary buffer, and zeroed
> >> > its region using dma_pool_zalloc.
> >>
> >> you're doing two separate things here...
> >>
> >> > Signed-off-by: Peter Chen <peter.chen@xxxxxxx>
> >> > ---
> >> > drivers/usb/host/xhci-mem.c | 21 +++++++++++++++------
> >> > drivers/usb/host/xhci.h | 1 +
> >> > 2 files changed, 16 insertions(+), 6 deletions(-)
> >> >
> >> > diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> >> > index 22a03b7..56aa0a6 100644
> >> > --- a/drivers/usb/host/xhci-mem.c
> >> > +++ b/drivers/usb/host/xhci-mem.c
> >> > @@ -1710,12 +1710,18 @@ static int scratchpad_alloc(struct xhci_hcd *xhci, gfp_t flags)
> >> > goto fail_sp3;
> >> >
> >> > xhci->dcbaa->dev_context_ptrs[0] = cpu_to_le64(xhci->scratchpad->sp_dma);
> >> > +
> >> > + xhci->scratchpad_pool = dma_pool_create("xhci scratchpad buffer pool",
> >> > + dev, xhci->page_size,
> >> > + xhci->page_size, xhci->page_size);
> >>
> >> adding a DMA pool here, and ...
> >>
> >> > + if (!xhci->scratchpad_pool)
> >> > + goto fail_sp4;
> >> > +
> >> > for (i = 0; i < num_sp; i++) {
> >> > dma_addr_t dma;
> >> > - void *buf = dma_alloc_coherent(dev, xhci->page_size, &dma,
> >> > - flags);
> >> > + void *buf = dma_pool_zalloc(xhci->scratchpad_pool, flags, &dma);
> >>
> >> ... fixing a possible bug here.
> >>
> >
> > I know it is two things, but after the dma pool is introduced, we need a
> > new API to allocate memory, do you want to me use dma_pool_alloc first,
> > then, change it to use dma_pool_zalloc at another patch? I am ok to do
> > that.
>
> the other way around. First you patch dma_alloc_coherent() to
> dma_zalloc_coherent() and that could go in during the -rc and possibly
> get a stable tag, since spec requires kernel to zero the memory area.
>
> --
> balbi
In fact, it fixes two things at spec, the other thing is the scratchpad
buffer needs to be page_size boundary. I will send these two fixes
first.
--
Best Regards,
Peter Chen
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