Re: [PATCH] PCI: endpoint: pci-epf-test: Roll back BAR mapping when subrange setup fails

[Niklas Cassel <cassel@kernel.org>]

On Tue, Mar 17, 2026 at 03:29:30PM +0530, Manivannan Sadhasivam wrote:
> > On 3/17/26 03:57, Koichiro Den wrote:
> > > On Mon, Mar 16, 2026 at 05:19:26PM +0100, Niklas Cassel wrote:
> > > > On Mon, Mar 16, 2026 at 11:02:25PM +0900, Koichiro Den wrote:
> > > > > When the BAR subrange mapping test on DWC-based platforms fails due to
> > > > > insufficient free inbound iATU regions,
> > > > > pci_epf_test_bar_subrange_setup() returns an error (-ENOSPC) but does
> > > > > not restore the original BAR mapping. This causes subsequent test runs
> > > > > to become confusing, since the failure may leave room for the next
> > > > > subrange mapping test to pass.
> > > > > 
> > > > > Fix this by restoring the original BAR mapping when preparation of the
> > > > > subrange mapping fails, so that no side effect remains regardless of the
> > > > > test success or failure.
> > > > > 
> > > > > Fixes: 6c5e6101423b ("PCI: endpoint: pci-epf-test: Add BAR subrange mapping test support")
> > > > > Reported-by: Christian Bruel <christian.bruel@foss.st.com>
> > > > > Closes: https://lore.kernel.org/linux-pci/b2b03ebe-9482-4a13-b22f-7b44da096eed@foss.st.com/
> > > > > Signed-off-by: Koichiro Den <den@valinux.co.jp>
> > > > > ---
> > > > >   drivers/pci/endpoint/functions/pci-epf-test.c | 6 ++++++
> > > > >   1 file changed, 6 insertions(+)
> > > > > 
> > > > > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > > > index 14e61ebe1f11..f44c36f5cac5 100644
> > > > > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > > > > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > > > > @@ -898,16 +898,22 @@ static void pci_epf_test_bar_subrange_setup(struct pci_epf_test *epf_test,
> > > > >   	bar->submap = submap;
> > > > >   	bar->num_submap = nsub;
> > > > >   	ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, bar);
> > > > >   	if (ret) {
> > > > >   		dev_err(&epf->dev, "pci_epc_set_bar() failed: %d\n", ret);
> > > > >   		bar->submap = old_submap;
> > > > >   		bar->num_submap = old_nsub;
> > > > > +		ret = pci_epc_set_bar(epc, epf->func_no, epf->vfunc_no, bar);
> > > > > +		if (ret)
> > > > > +			dev_warn(&epf->dev,
> > > > > +				 "failed to restore the original BAR mapping: %d\n",
> > > > 
> > > > Nit:
> > > > I would use a capitalized F:
> > > > "Failed to restore ..."
> > > > 
> > > > in order to match most other prints in this file.
> > > 
> > > Agree. Bjorn or Mani, please feel free to fix this up (i.e. s/failed/Failed/)
> > > when applying, to avoid a respin for such a minor change.
> > > 
> > > > 
> > > > Reviewed-by: Niklas Cassel <cassel@kernel.org>
> > > 
> > > Thanks again for reviewing, Niklas.
> > > 
> > > Christian, if possible, it would be very helpful if you could take a look or
> > > test this slightly polished version and add a Tested-by or Reviewed-by.
> > 
> > Tested-by: Christian Bruel <christian.bruel@foss.st.com>
> > 
> > with the DISABLE BAR dependency
> > https://git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=endpoint&id=33642e9e36dc084e4fc9245a266c9843bc8303b9
> > 
> 
> Why is this dependency?

It is not.

I just suggested to force disable a BAR on STM32, using this patch, so that
Christian could verify that the new feature can actually work on STM32.

(Another option would have been to modify pci-epf-test to not enable all
6 BARs.)


Kind regards,
Niklas