On Wed, Mar 05, 2025 at 12:46:38AM +0900, Krzysztof Wilczyński wrote:
> Hello,
>
> > This patch is now commit 1ff54f4cbaed9ec6 ("PCI: dwc: Add debugfs
> > based Silicon Debug support for DWC") in pci/next (next-20250304).
> >
> > On Mon, 3 Mar 2025 at 20:47, Krzysztof Wilczyński <kw@xxxxxxxxx> wrote:
> > > [...]
> > > > > +int dwc_pcie_debugfs_init(struct dw_pcie *pci)
> > > > > +{
> > > > > + char dirname[DWC_DEBUGFS_BUF_MAX];
> > > > > + struct device *dev = pci->dev;
> > > > > + struct debugfs_info *debugfs;
> > > > > + struct dentry *dir;
> > > > > + int ret;
> > > > > +
> > > > > + /* Create main directory for each platform driver */
> > > > > + snprintf(dirname, DWC_DEBUGFS_BUF_MAX, "dwc_pcie_%s", dev_name(dev));
> > > > > + dir = debugfs_create_dir(dirname, NULL);
> > > > > + debugfs = devm_kzalloc(dev, sizeof(*debugfs), GFP_KERNEL);
> > > > > + if (!debugfs)
> > > > > + return -ENOMEM;
> > > > > +
> > > > > + debugfs->debug_dir = dir;
> > > > > + pci->debugfs = debugfs;
> > > > > + ret = dwc_pcie_rasdes_debugfs_init(pci, dir);
> > > > > + if (ret)
> > > > > + dev_dbg(dev, "RASDES debugfs init failed\n");
> > > >
> > > > What will happen if ret != 0? still return 0?
> >
> > And that is exactly what happens on Gray Hawk Single with R-Car
> > V4M: dw_pcie_find_rasdes_capability() returns NULL, causing
> > dwc_pcie_rasdes_debugfs_init() to return -ENODEV.
>
> Thank you for testing and for catching this issue. Much appreciated.
>
> > > Given that callers of dwc_pcie_debugfs_init() check for errors,
> >
> > Debugfs issues should never be propagated upstream!
>
> Makes complete sense. Sorry for breaking things here!
>
> > > this probably should correctly bubble up any failure coming from
> > > dwc_pcie_rasdes_debugfs_init().
> > >
> > > I made updates to the code directly on the current branch, have a look:
> >
> > So while applying, you changed this like:
> >
> > ret = dwc_pcie_rasdes_debugfs_init(pci, dir);
> > - if (ret)
> > - dev_dbg(dev, "RASDES debugfs init failed\n");
> > + if (ret) {
> > + dev_err(dev, "failed to initialize RAS DES debugfs\n");
> > + return ret;
> > + }
> >
> > return 0;
> >
> > Hence this is now a fatal error, causing the probe to fail.
>
> I removed the changed, and also move the log level to be a warning, per:
>
> https://web.git.kernel.org/pub/scm/linux/kernel/git/pci/pci.git/commit/?h=controller/dwc&id=c6759a967e69aba16aef0d92f43e527b112e98a5
>
> Would this be acceptable here?
>
> Mani, would this be acceptable to you, too? Given that you posted the
> following recently:
>
> https://lore.kernel.org/linux-pci/20250303200055.GA1881771@rocinante/T/#mab9cbd5834390d259afea056eee9a73d8c3b435f
>
> That said, perhaps moving the log level to a debug would be better served here.
>
Even though debugfs_init() failure is not supposed to fail the probe(),
dwc_pcie_rasdes_debugfs_init() has a devm_kzalloc() and propagating that
failure would be canolically correct IMO.
So I would still opt to have my version + your previous one.
- Mani
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