> Subject: Re: [PATCH 2/4] RDMA/core: Set DMA parameters correctly
>
> On 10/21/19 10:44 AM, Saleem, Shiraz wrote:
> >> diff --git a/drivers/infiniband/core/device.c
> >> b/drivers/infiniband/core/device.c
> >> index a667636f74bf..a523d844ad9d 100644
> >> --- a/drivers/infiniband/core/device.c
> >> +++ b/drivers/infiniband/core/device.c
> >> @@ -1199,9 +1199,21 @@ static void setup_dma_device(struct ib_device
> *device)
> >> WARN_ON_ONCE(!parent);
> >> device->dma_device = parent;
> >> }
> >> - /* Setup default max segment size for all IB devices */
> >> - dma_set_max_seg_size(device->dma_device, SZ_2G);
> >>
> >> + if (!device->dev.dma_parms) {
> >> + if (parent) {
> >> + /*
> >> + * The caller did not provide DMA parameters, so
> >> + * 'parent' probably represents a PCI device. The PCI
> >> + * core sets the maximum segment size to 64
> >> + * KB. Increase this parameter to 2G.
> >> + */
> >> + device->dev.dma_parms = parent->dma_parms;
> >> + dma_set_max_seg_size(device->dma_device, SZ_2G);
> >
> > Did you mean dma_set_max_seg_size(&device->dev, SZ_2G)?
>
> Have you realized that that call has the same effect as what I proposed since both
> devices share the dma_parms parameter?
>
I hadn’t. This makes more sense now.
