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

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Date:   Thu, 14 Dec 2023 16:24:21 +0530
From:   Krishna Chaitanya Chundru <quic_krichai@...cinc.com>
To:     Manivannan Sadhasivam <mani@...nel.org>
CC:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        <lpieralisi@...nel.org>, <kw@...ux.com>, <kishon@...nel.org>,
        <bhelgaas@...gle.com>, <mhi@...ts.linux.dev>,
        <linux-arm-msm@...r.kernel.org>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 6/9] PCI: epf-mhi: Enable MHI async read/write support


On 12/14/2023 4:17 PM, Manivannan Sadhasivam wrote:
> On Thu, Dec 14, 2023 at 03:44:21PM +0530, Krishna Chaitanya Chundru wrote:
>> 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@...aro.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;
>> 	}
> Are you reading the patch correctly? Please take a look at this commit:
> https://git.kernel.org/pub/scm/linux/kernel/git/mani/mhi.git/tree/drivers/pci/endpoint/functions/pci-epf-mhi.c?h=mhi-next&id=d1c6f4ba4746ed41fde8269cb5fea88bddb60504#n771
>
> - Mani

Sorry for the noise, I didn't notice else is also removed.

- Krishna Chaitanya.

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