Re: [PATCH v2 2/7] PCI: epf-mhi: Make use of the alignment restriction from EPF core

[Bjorn Helgaas]

On Mon, Jul 17, 2023 at 12:24:54PM +0530, Manivannan Sadhasivam wrote:
> Instead of hardcoding the alignment restriction in the EPF_MHI driver, make
> use of the info available from the EPF core that reflects the alignment
> restriction of the endpoint controller.
> 
> For this purpose, let's introduce the get_align_offset() static function.

I thought this might be related to the [1/7] patch since they both
mention an alignment restriction in the EPF core, but [1/7] sets
pci_epc_features.align and this patch doesn't reference .align, so
this must be a different alignment restriction?

I'm sure there's nothing wrong here, and this is already applied, so
no need to do anything unless .align *should* appear here.

> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> ---
>  drivers/pci/endpoint/functions/pci-epf-mhi.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-mhi.c b/drivers/pci/endpoint/functions/pci-epf-mhi.c
> index 9c1f5a154fbd..bb7de6884824 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-mhi.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-mhi.c
> @@ -102,6 +102,11 @@ struct pci_epf_mhi {
>  	int irq;
>  };
>  
> +static size_t get_align_offset(struct pci_epc *epc, u64 addr)
> +{
> +	return addr % epc->mem->window.page_size;
> +}
> +
>  static int __pci_epf_mhi_alloc_map(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
>  				 phys_addr_t *paddr, void __iomem **vaddr,
>  				 size_t offset, size_t size)
> @@ -134,7 +139,7 @@ static int pci_epf_mhi_alloc_map(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
>  {
>  	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
>  	struct pci_epc *epc = epf_mhi->epf->epc;
> -	size_t offset = pci_addr & (epc->mem->window.page_size - 1);
> +	size_t offset = get_align_offset(epc, pci_addr);
>  
>  	return __pci_epf_mhi_alloc_map(mhi_cntrl, pci_addr, paddr, vaddr,
>  				      offset, size);
> @@ -161,7 +166,7 @@ static void pci_epf_mhi_unmap_free(struct mhi_ep_cntrl *mhi_cntrl, u64 pci_addr,
>  	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
>  	struct pci_epf *epf = epf_mhi->epf;
>  	struct pci_epc *epc = epf->epc;
> -	size_t offset = pci_addr & (epc->mem->window.page_size - 1);
> +	size_t offset = get_align_offset(epc, pci_addr);
>  
>  	__pci_epf_mhi_unmap_free(mhi_cntrl, pci_addr, paddr, vaddr, offset,
>  				 size);
> @@ -185,7 +190,8 @@ static int pci_epf_mhi_read_from_host(struct mhi_ep_cntrl *mhi_cntrl, u64 from,
>  				      void *to, size_t size)
>  {
>  	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
> -	size_t offset = from % SZ_4K;
> +	struct pci_epc *epc = epf_mhi->epf->epc;
> +	size_t offset = get_align_offset(epc, from);
>  	void __iomem *tre_buf;
>  	phys_addr_t tre_phys;
>  	int ret;
> @@ -213,7 +219,8 @@ static int pci_epf_mhi_write_to_host(struct mhi_ep_cntrl *mhi_cntrl,
>  				     void *from, u64 to, size_t size)
>  {
>  	struct pci_epf_mhi *epf_mhi = to_epf_mhi(mhi_cntrl);
> -	size_t offset = to % SZ_4K;
> +	struct pci_epc *epc = epf_mhi->epf->epc;
> +	size_t offset = get_align_offset(epc, to);
>  	void __iomem *tre_buf;
>  	phys_addr_t tre_phys;
>  	int ret;
> -- 
> 2.25.1
>