Re: [PATCH 6/9] PCI: epf-mhi: Enable MHI async read/write support

[Krishna Chaitanya Chundru]

On 12/14/2023 3:39 PM, Manivannan Sadhasivam wrote:
> On Thu, Dec 14, 2023 at 03:10:01PM +0530, Krishna Chaitanya Chundru wrote:
> > On 11/27/2023 6:15 PM, Manivannan Sadhasivam wrote:
> > > Now that both eDMA and iATU are prepared to support async transfer, let's
> > > enable MHI async read/write by supplying the relevant callbacks.
> > >
> > > In the absence of eDMA, iATU will be used for both sync and async
> > > operations.
> > >
> > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> > > ---
> > >    drivers/pci/endpoint/functions/pci-epf-mhi.c | 7 ++++---
> > >    1 file changed, 4 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/drivers/pci/endpoint/functions/pci-epf-mhi.c b/drivers/pci/endpoint/functions/pci-epf-mhi.c
> > > index 3d09a37e5f7c..d3d6a1054036 100644
> > > --- a/drivers/pci/endpoint/functions/pci-epf-mhi.c
> > > +++ b/drivers/pci/endpoint/functions/pci-epf-mhi.c
> > > @@ -766,12 +766,13 @@ static int pci_epf_mhi_link_up(struct pci_epf *epf)
> > >    	mhi_cntrl->raise_irq = pci_epf_mhi_raise_irq;
> > >    	mhi_cntrl->alloc_map = pci_epf_mhi_alloc_map;
> > >    	mhi_cntrl->unmap_free = pci_epf_mhi_unmap_free;
> > > +	mhi_cntrl->read_sync = mhi_cntrl->read_async = pci_epf_mhi_iatu_read;
> > > +	mhi_cntrl->write_sync = mhi_cntrl->write_async = pci_epf_mhi_iatu_write;
> > >    	if (info->flags & MHI_EPF_USE_DMA) {
> > >    		mhi_cntrl->read_sync = pci_epf_mhi_edma_read;
> > >    		mhi_cntrl->write_sync = pci_epf_mhi_edma_write;
> > > -	} else {
> > > -		mhi_cntrl->read_sync = pci_epf_mhi_iatu_read;
> > > -		mhi_cntrl->write_sync = pci_epf_mhi_iatu_write;
> > > +		mhi_cntrl->read_async = pci_epf_mhi_edma_read_async;
> > > +		mhi_cntrl->write_async = pci_epf_mhi_edma_write_async;
> > I think the read_async & write async should be updated inside the if
> > condition where MHI_EPF_USE_DMA flag is set.
> That's what being done here. Am I missing anything?
>
> - Mani

It should be like this as edma sync & aysnc read write should be update 
only if DMA is supported, in the patch I see async function pointers are 
being updated with the edma function pointers for IATU operations.

                if (info->flags & MHI_EPF_USE_DMA) {

  		mhi_cntrl->read_sync = pci_epf_mhi_edma_read;
  		mhi_cntrl->write_sync = pci_epf_mhi_edma_write;
		mhi_cntrl->read_async = pci_epf_mhi_edma_read_async;
		mhi_cntrl->write_async = pci_epf_mhi_edma_write_async;
	}
- Krishna Chaitanya.

> > - Krishna Chaitanya.
> >
> > >    	}
> > >    	/* Register the MHI EP controller */