On Wed, Nov 20, 2024 at 06:05:31PM +0100, Niklas Cassel wrote: > On Wed, Nov 20, 2024 at 11:53:29AM -0500, Frank Li wrote: > > On Wed, Nov 20, 2024 at 04:57:33PM +0100, Niklas Cassel wrote: > > > If running pci_endpoint_test.c (host side) against a version of > > > pci-epf-test.c (EP side), we will not see any capabilities being set. > > > > > > For now, only add the CAP_HAS_ALIGN_ADDR capability. > > > > > > If the CAP_HAS_ALIGN_ADDR is set, that means that the EP side supports > > > reading/writing to an address without any alignment requirements. > > > > > > Thus, if CAP_HAS_ALIGN_ADDR is set, make sure that we do not add any > > > specific padding to the buffers that we allocate (which was only made > > > in order to get the buffers to satisfy certain alignment requirements). > > > > > > Signed-off-by: Niklas Cassel <cassel@xxxxxxxxxx> > > > --- > > > drivers/misc/pci_endpoint_test.c | 21 +++++++++++++++++++++ > > > 1 file changed, 21 insertions(+) > > > > > > diff --git a/drivers/misc/pci_endpoint_test.c b/drivers/misc/pci_endpoint_test.c > > > index 3aaaf47fa4ee..ab2b322410fb 100644 > > > --- a/drivers/misc/pci_endpoint_test.c > > > +++ b/drivers/misc/pci_endpoint_test.c > > > @@ -69,6 +69,9 @@ > > > #define PCI_ENDPOINT_TEST_FLAGS 0x2c > > > #define FLAG_USE_DMA BIT(0) > > > > > > +#define PCI_ENDPOINT_TEST_CAPS 0x30 > > > +#define CAP_HAS_ALIGN_ADDR BIT(0) > > > + > > > #define PCI_DEVICE_ID_TI_AM654 0xb00c > > > #define PCI_DEVICE_ID_TI_J7200 0xb00f > > > #define PCI_DEVICE_ID_TI_AM64 0xb010 > > > @@ -805,6 +808,22 @@ static const struct file_operations pci_endpoint_test_fops = { > > > .unlocked_ioctl = pci_endpoint_test_ioctl, > > > }; > > > > > > +static void pci_endpoint_test_get_capabilities(struct pci_endpoint_test *test) > > > +{ > > > + struct pci_dev *pdev = test->pdev; > > > + struct device *dev = &pdev->dev; > > > + u32 caps; > > > + bool has_align_addr; > > > + > > > + caps = pci_endpoint_test_readl(test, PCI_ENDPOINT_TEST_CAPS); > > > > I worry about if there are problem if EP have not such register. for > > example, if reg's space size is 64, but host try to read pos 68. I think it > > is original design problem, it should have one 'version' or 'size' in > > register list. > > Hello Frank, > > The test BAR is allocated using pci_epf_alloc_space(), which allocates the > backing memory using dma_alloc_coherent(), which will return zeroed memory > regardless of __GFP_ZERO was set or not. > > This means that running a new version of pci-endpoint-test.c (host side) > with and old version of pci-epf-test.c (EP side) will not see any > capabilities being set (as intended), so this is backwards compatible. > > > And as you probably know, pci-epf-test will always allocate at least 128 Can you add such information to commit message? Frank > bytes for the test BAR: > https://github.com/torvalds/linux/blob/v6.12/drivers/pci/endpoint/functions/pci-epf-test.c#L833 > > This patch uses: > #define PCI_ENDPOINT_TEST_CAPS 0x30 > > 0x30 == 48, so we are currently only using 49 bytes. > > So we should be good. > > > Kind regards, > Niklas