On Thu, Sep 04, 2025 at 11:40:15AM +0900, Damien Le Moal wrote:
> On 9/4/25 11:37 AM, Marek Vasut wrote:
> > Currently, the test allocates BAR sizes according to fixed table
> > bar_size[] = { 512, 512, 1024, 16384, 131072, 1048576 } . This
> > does not work with controllers which have fixed size BARs, like
> > Renesas R-Car V4H PCIe controller, which has BAR4 size limited
> > to 256 Bytes, which is much less than 131072 currently requested
> > by this test.
> >
> > Adjust the test such, that in case a fixed size BAR is detected
> > on a controller, minimum of requested size and fixed size BAR
> > size is used during the test instead.
> >
> > This helps with test failures reported as follows:
> > "
> > pci_epf_test pci_epf_test.0: requested BAR size is larger than fixed size
> > pci_epf_test pci_epf_test.0: Failed to allocate space for BAR4
> > "
> >
> > Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>
> > ---
> > Cc: "Krzysztof Wilczyński" <kwilczynski@xxxxxxxxxx>
> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
> > Cc: Damien Le Moal <dlemoal@xxxxxxxxxx>
> > Cc: Frank Li <Frank.Li@xxxxxxx>
> > Cc: Kishon Vijay Abraham I <kishon@xxxxxxxxxx>
> > Cc: Manivannan Sadhasivam <mani@xxxxxxxxxx>
> > Cc: Niklas Cassel <cassel@xxxxxxxxxx>
> > Cc: Wang Jiang <jiangwang@xxxxxxxxxx>
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Cc: linux-pci@xxxxxxxxxxxxxxx
> > Cc: linux-renesas-soc@xxxxxxxxxxxxxxx
> > ---
> > drivers/pci/endpoint/functions/pci-epf-test.c | 11 +++++++++--
> > 1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > index e091193bd8a8a..d9c950d4c9a9e 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > @@ -1022,7 +1022,8 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
> > enum pci_barno test_reg_bar = epf_test->test_reg_bar;
> > enum pci_barno bar;
> > const struct pci_epc_features *epc_features = epf_test->epc_features;
> > - size_t test_reg_size;
> > + size_t test_reg_size, test_bar_size;
> > + u64 bar_fixed_size;
> >
> > test_reg_bar_size = ALIGN(sizeof(struct pci_epf_test_reg), 128);
> >
> > @@ -1050,7 +1051,13 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf)
> > if (bar == test_reg_bar)
> > continue;
> >
> > - base = pci_epf_alloc_space(epf, bar_size[bar], bar,
> > + test_bar_size = bar_size[bar];
> > +
> > + bar_fixed_size = epc_features->bar[bar].fixed_size;
> > + if (epc_features->bar[bar].type == BAR_FIXED && bar_fixed_size)
> > + test_bar_size = min(bar_size[bar], bar_fixed_size);
>
> I think this can be simplified to:
>
> if (epc_features->bar[bar].type == BAR_FIXED)
> test_bar_size = epc_features->bar[bar].fixed_size;
> else
> test_bar_size = bar_size[bar];
+1
>
> because if the bar type is BAR_FIXED, then the size of the bar can only be its
> fixed size.
Correct, see:
f015b53d634a ("PCI: endpoint: Add size check for fixed size BARs in pci_epc_set_bar()")
Actually, Jerome Brunet was also using this weird Renesas R-Car V4H PCIe
controller where BAR4 is a really small fixed-size BAR.
(Even smaller than the iATU minimum alignment requirement for that same
controller.)
See:
793908d60b87 ("PCI: endpoint: Retain fixed-size BAR size as well as aligned size")
But he only appears to have used the vntb epf driver.
Jerome, I suppose that you never ran with the pci-epf-test driver?
pci_epf_alloc_space() works like this:
If the user requests a BAR size that is smaller than the fixed-size BAR,
it will allocate space matching the fixed-size.
As in most cases, having a BAR larger than needed by an EPF driver is
still acceptable.
However, if the user requests a size larger than the fixed-size BAR,
as in your case, we will return an error, as we cannot fulfill the
user's request.
I don't see any alternative other than your/Damien's proposal above.
Unfortunately, all EPF drivers would probably need this same change.
Kind regards,
Niklas
