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

Krishna Chaitanya Chundru
2023-12-14T10:14:46Z

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@linaro.org>
>>> ---
>>> 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 */